10-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

 Washington, D.C. 20549

FORM 10-K

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2023

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from ______ to ______

Commission file number 0-24531

CoStar Group, Inc.

(Exact name of registrant as specified in its charter)

Delaware	52-2091509
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)

1331 L Street, NW
Washington,	DC	20005

(Address of principal executive offices) (zip code)

(202) 346-6500

(Registrant’s telephone number, including area code)

 Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol	Name of each exchange on which registered
Common Stock ($0.01 par value)	CSGP	Nasdaq Global Select Market

Securities registered pursuant to section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

Yes x No o

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

Yes o No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days.

Yes x   No o 

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

Yes x   No o 

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and "emerging growth company" in Rule 12b-2 of the Exchange Act.

Large accelerated filer	x	Accelerated filer	o
Non-accelerated filer	o	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

o

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.

x

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.

o

Indicate by checkmark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b).

o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).     

Yes ☐   No x

As of June 30, 2023, the aggregate market value of the common stock (based upon the closing price of the stock on the Nasdaq Global Select Market) of the registrant held by non-affiliates was approximately $36.0 billion. As of February 16, 2024, 408,409,321 shares of common stock were outstanding.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive proxy statement, which is expected to be filed with the Securities and Exchange Commission within 120 days after the end of the registrant’s fiscal year ended December 31, 2023 are incorporated by reference into Part III of this Report.

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TABLE OF CONTENTS

	Glossary of Terms	4
PART I
Item 1.	Business	7
Item 1A.	Risk Factors	20
Item 1B.	Unresolved Staff Comments	32
Item 1C	Cybersecurity	33
Item 2.	Properties	34
Item 3.	Legal Proceedings	34
Item 4.	Mine Safety Disclosures	34
PART II
Item 5.	Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities	35
Item 6.	Reserved	37
Item 7.	Management’s Discussion and Analysis of Financial Condition and Results of Operations	38
Item 7A.	Quantitative and Qualitative Disclosures about Market Risk	49
Item 8.	Financial Statements and Supplementary Data	51
Item 9.	Changes in and Disagreements with Accountants on Accounting and Financial Disclosure	51
Item 9A.	Controls and Procedures	51
Item 9B.	Other Information	52
Item 9C.	Disclosure Regarding Foreign Jurisdictions that Prevent Inspections	52
PART III
Item 10.	Directors, Executive Officers and Corporate Governance	52
Item 11.	Executive Compensation	52
Item 12.	Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters	52
Item 13.	Certain Relationships and Related Transactions, and Director Independence	52
Item 14.	Principal Accountant Fees and Services	52
PART IV
Item 15.	Exhibits and Financial Statement Schedules	53
Item 16.	Form 10-K Summary	56
	Signatures	57
	Index to Consolidated Financial Statements	F-1

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Glossary of Terms

The following abbreviations or acronyms used in this Annual Report on Form 10-K (this "Report") are defined below:

Abbreviation or Acronym	Definition
2020 Credit Agreement	The second amended and restated credit agreement, dated July 1, 2020, which amended and restated in its entirety the then-existing credit agreement originally entered into on April 1, 2014, as amended by the first amendment to the second amended and restated credit agreement, dated May 8, 2023.
ACH	Automated Clearing House
ADR	Average daily rate
Apartments.com Network	Apartments.com, the flagship brand of our network of apartment marketing sites, and its network of rental websites
ARS	Auction rate securities
ASC	Accounting Standards Codification
ASU	Accounting Standards Update
Audit Committee	The Audit Committee of the Board
BizBuySell	BizBuySell.com and its network of business for-sale websites
Board	The CoStar Group Board of Directors
BureauxLocaux	The legal entity, Comreal Info, a French société par actions simplifiée, the owner and operator of BureauxLocaux, a commercial real estate digital marketplace, in France
BureauxLocaux Acquisition	CoStar UK's acquisition of BureauxLocaux completed on October 1, 2021 pursuant to a Share Sale and Purchase Agreement dated October 1, 2021 between CoStar UK, M.A.J.E. Marketing & Strategie and an individual
Business Immo	The legal entity BIH, a French société par actions simplifiée, the owner and operator of Business Immo, a leading commercial real estate news service provider in France
Business Immo Acquisition	CoStar UK's acquisition of the issued share capital of Business Immo on April 5, 2022
CAN-SPAM Act	Controlling the Assault of Non-Solicited Pornography and Marketing Act
CCPA	California Consumer Privacy Act, as amended by the California Privacy Rights Act
CECL	Current expected credit losses
CMBS	Commercial mortgage-based securities
CODM	Chief Operating Decision Maker
Confidential Information	Information about customers, employees, contractors, suppliers, vendors, and others such as landlords and tenants, including personal information such as names, addresses, phone numbers, email addresses, credit card information, biometric data, sensitive or confidential transaction and account information, social security numbers, birthdates and financial information (for example, to facilitate the apartment rental application and payment process between a renter and property manager), as well as a broad range of proprietary and confidential business information, collectively
CoStar Group	The legal entity, CoStar Group, Inc., a Delaware corporation, one or more of its consolidated subsidiaries or operating segments, or the entirety of CoStar Group, Inc. and its consolidated subsidiaries
CoStar UK	The legal entity, CoStar UK Limited, a wholly owned subsidiary of CoStar Group
Covenant Suspension Period	A period of time defined in the 2020 Credit Agreement in which we maintain a corporate investment grade rating from any two of Standard & Poor’s Rating Services, Fitch Ratings, Inc. or Moody’s Investors Services, Inc. and no event of default is continuing
CPA	Colorado Privacy Act
CPRA	The California Privacy Rights Act

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Abbreviation or Acronym	Definition
CRI	CoStar Realty Information, Inc., a Delaware corporation and wholly owned subsidiary of CoStar Group, Inc.
DSUs	Deferred Stock Units
E.U.	European Union
EBITDA	Net income before interest income or expense, net; other income or expense, net; loss on debt extinguishment; income taxes; depreciation and amortization
ESG	Environmental, Social and Governance
ESPP	Employee Stock Purchase Plan
EURIBOR	Euro Interbank Offered Rate
FASB	Financial Accounting Standards Board
FCRA	Fair Credit Reporting Act
FTC	Federal Trade Commission
GAAP	Generally accepted accounting principles in the U.S.
GDPR	General Data Protection Regulation
GILTI	Global intangible low taxed income inclusion
GPP Plan	A U.K. Group Personal Pension Plan
Halo Merger Sub	Snapped Halo Merger Sub Corp., a Delaware corporation and wholly owned subsidiary of CoStar Realty Information, Inc.
Homes.com	A homes-for-sale listings site
Homes Group	The legal entity Homes Group, LLC
Homes.com Acquisition	CRI's acquisition of Homes.com completed on May 24, 2021 pursuant to a securities purchase agreement dated April 14, 2021 between Landmark, Homes Group, LLC and CRI
Homes.com Network	Homes.com, the flagship brand of our North American network of online platforms that manage workflow and marketing for residential real estate agents and brokers and provide portals for homebuyers to view residential property listings
Homesnap	Homesnap is an online and mobile software platform that provides residential real estate professionals access to applications that manage residential real estate agent workflow and marketing campaigns delivered on third-party platforms acquired in the Homesnap Acquisition
Homesnap, Inc.	The legal entity Homesnap, Inc., a Delaware corporation
Homesnap Acquisition	CRI's acquisition of Homesnap completed on December 22, 2020, pursuant to an Agreement and Plan of Merger dated November 20, 2020 between CRI, Halo Merger Sub Corp and Homesnap, Inc. Halo Merger Sub Corp. was merged with and into Homesnap, Inc., with Homesnap, Inc. surviving the merger as a wholly-owned subsidiary of CRI
ILS	Internet listings services
IT Systems	Information technology networks, systems and infrastructure to process, transmit and store electronic information and to communicate among our locations around the world and with our clients and vendors, collectively
Land.com Network	Our network of sites featuring rural lands for sale including: LandsofAmerica, LandAndFarm and LandWatch
Landmark	Landmark Media Enterprises, LLC
LIBOR	London Interbank Offered Rate
LoopNet Network	Our network of online marketplaces, including LoopNet.co.uk, CityFeet.com and Showcase.com, enabling commercial property owners, landlords and real estate brokers working on their behalf to advertise properties for-sale or for-lease and to submit detailed information about property listings
Matching RSUs	Awards of matching restricted stock units awarded under the Company's Management Stock Purchase Plan
MLS	Multiple listing services
MSPP	Management Stock Purchase Plan

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Abbreviation or Acronym	Definition
OnTheMarket	The legal entity OnTheMarket Plc, the operator of onthemarket.com, a leading U.K. residential property portal.
OnTheMarket Acquisition	CoStar UK's acquisition of OnTheMarket completed in December 2023, pursuant to Rule 2.7 of the United Kingdom City Code on Takeovers and Mergers. The acquisition has been implemented by means of a court-sanctioned scheme of arrangement under the U.K. Companies Act 2006
RentPath	RentPath Holdings, Inc.
RevPAR	Revenue per available room
ROU	Right-of-use
RRSP	A Canadian registered retirement savings plan
SEC	U.S. Securities and Exchange Commission
Securities Act	Securities Act of 1933, as amended
SEM	Search Engine Marketing
Senior Notes	2.800% notes issued by CoStar Group, Inc. due July 15, 2030
SEO	Search Engine Optimization
SOFR	Secured Overnight Financing Rate
SONIA	Sterling Overnight Index Average
STAR Report	A benchmarking tool used by the hospitality industry to compare a hotel's performance against a set of similar hotels in the same geographical area
STR	STR, LLC together with STR Global Ltd is a global data and analytics company that specializes in benchmarking hotel performance and providing market insights to the industry
TCPA	Telephone Consumer Protection Act (as implemented by the Telemarketing Sales Rule)
Ten-X	The legal entity Ten-X Holding Company, Inc. and its directly and indirectly owned subsidiaries
Ten-X Acquisition	CRI's acquisition of Ten-X completed on June 24, 2020, pursuant to an Agreement and Plan of Merger dated May 13, 2020 between CRI, Crescendo Sub, Inc, and Ten-X
Term SOFR	The forward-looking SOFR term rates administered by CME Group Benchmark Administration Limited
TSR	Total shareholder return
U.K.	The United Kingdom of Great Britain and Northern Ireland
U.S.	The United States of America
UCPA	Utah Consumer Privacy Act
VCDPA	Virginia Consumer Data Protection Act

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Cautionary Statement Concerning Forward-Looking Statements

We have made forward-looking statements in this Report and make forward-looking statements in our other reports filed with the SEC, press releases and conference calls that are subject to risks and uncertainties. Forward-looking statements include information that is not purely historic fact and include, without limitation, statements concerning our financial outlook for the year ending December 31, 2024 and beyond, our possible or assumed future results of operations generally and other statements and information regarding assumptions or expectations about our revenues, revenue growth rates, gross margin percentage, net income, net income per share, fully diluted net income per share, EBITDA, adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income, non-GAAP net income per diluted share, weighted-average outstanding shares, cash flow from operating activities, operating costs, capital and other expenditures, the impact of current economic conditions on our revenues, revenue growth rates and profitability, key priorities for the year ending December 31, 2024, trends in customer behavior, legal proceedings and claims, legal costs, effective tax rate, product development and release, the anticipated benefits of completed or proposed acquisitions, the anticipated timing of acquisition closings and integrations, the anticipated benefits of cross-selling efforts, geographic and product expansion, planned service enhancements, expansion and development of our sales forces, planned sales and marketing activities and investments, investments in residential marketplace services and our residential marketplace strategy, the impact or results of sales and marketing initiatives, product integrations, elimination and de-emphasizing of services, net new bookings, contract renewal rates, use of proceeds from equity and debt offerings, the use of proceeds from any draws under our $750 million credit facility provided by the 2020 Credit Agreement, expectations regarding our compliance with financial and restrictive covenants in the 2020 Credit Agreement, employee relations, management’s plans, goals and objectives for future operations, sources and adequacy of liquidity and growth and markets for our stock. Sections of this Report that contain forward-looking statements include “Business,” “Risk Factors,” “Properties,” “Legal Proceedings,” “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” “Quantitative and Qualitative Disclosures About Market Risk,” “Controls and Procedures” and the Consolidated Financial Statements and related Notes.

Our forward-looking statements are also identified by words such as “hope,” “anticipate,” “may,” “believe,” “expect,” “intend,” “will,” “should,” “plan,” “estimate,” “predict,” “continue” and “potential” or the negative of these terms or other comparable terminology. You should understand that these forward-looking statements are estimates reflecting our judgment, beliefs and expectations, not guarantees of future performance. They are subject to a number of assumptions, risks and uncertainties that could cause actual results to differ materially from those expressed or implied in the forward-looking statements. The following important factors, in addition to those discussed or referred to under the heading “Risk Factors,” and other unforeseen events or circumstances, could affect our future results and could cause those results or other outcomes to differ materially from those expressed or implied in our forward-looking statements:

•our inability to attract and retain new clients;

•our inability to successfully develop and introduce new or updated information, analytics and online marketplace services;

•our inability to compete successfully against existing or future competitors in attracting advertisers and in general;

•competition;

•the effects of fluctuations and market cyclicality;

•the effects of global economic uncertainties and downturns or a downturn or consolidation in the real estate industry;

•our inability to hire qualified persons for, or retain and continue to develop, our sales force, or unproductivity of our sales force;

•our inability to retain and attract highly capable management and operating personnel;

•the downward pressure that our internal and external investments may place on our operating margins;

•our inability in increasing brand awareness;

•our inability to maintain or increase internet traffic to our marketplaces, and the risk that the methods, including Google Analytics, that we use to measure unique visitors to our portals may misstate the actual number of unique persons who visit our network of mobile applications and websites for a given month or may differ from the methods used by competitors;

•our inability to attract new advertisers;

•our inability to successfully identify, finance, integrate and/or manage costs related to acquisitions;

•the effects of cyberattacks and security vulnerabilities, and technical problems or disruptions;

•the risks related to a large infrastructure project to build out our campus in Richmond, Virginia;

•our inability to generate increased revenues from our current or future geographic expansion plans;

•the risks related to acceptance of credit cards and debit cards and facilitation of other customer payments;

•the effects of climate change and other events beyond our control;

•the effects related to increased attention to ESG matters;

•our inability to obtain and maintain accurate, comprehensive or reliable data;

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•our ability to enforce or defend our ownership and use of intellectual property;

•our inability to successfully halt the operation of websites that aggregate our data, data from other companies or “copycat” websites that may misappropriate our data;

•our inability to defend against potential legal liability for collecting, displaying or distributing information;

•our inability to obtain or retain listings from real estate brokers, agents, property owners and apartment property managers;

•our ability to maintain or establish relationships with third-party listing providers;

•our ability to comply with the rules and compliance requirements of MLSs;

•the risks related to international operations;

•the effects of foreign currency fluctuations;

•the effects of Brexit;

•our indebtedness;

•the effects of a lowering or withdrawal of the ratings assigned to our debt securities by rating agencies;

•the effects of any actual or perceived failure to comply with privacy or data protection laws, regulations or standards;

•the effects of changes in tax laws, regulations or fiscal and tax policies;

•the effects of third-party claims, litigation, regulatory proceedings or government investigations; and

•risks related to return on investment.

Accordingly, you should not place undue reliance on forward-looking statements, which speak only as of, and are based on information available to us on, the date of this Report. All subsequent written and oral forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We do not undertake any obligation to update any such statements or release publicly any revisions to these forward-looking statements to reflect new information or events or circumstances after the date of this Report or to reflect the occurrence of unanticipated events.

PART I

Item 1.    Business

In this Report, the words “we,” “our,” “us,” “CoStar Group” or the “Company” refer to CoStar Group, Inc. and its direct and indirect wholly owned subsidiaries. This Report also refers to our websites, but information contained on those sites is not part of this Report.

CoStar Group, founded in 1987, is a leading provider of online real estate marketplaces, information and analytics in the U.S. and U.K. based on the fact that we own and operate leading online marketplaces for commercial real estate and apartment listings in the U.S., based on the numbers of unique visitors and site visits per month; provide more information, analytics and marketing services than any of our competitors; offer the most comprehensive commercial real estate database available; and have the largest commercial real estate research department in the industry. We have created and compiled a standardized platform of information, analytics and online marketplace services where industry professionals and consumers of commercial real estate, including apartments, and the related business communities, can continuously interact and facilitate transactions by efficiently accessing and exchanging accurate and standardized real estate-related information. Our service offerings span all commercial property types, including office, retail, industrial, multifamily, land, mixed-use and hospitality. Through our Homes.com Network and our acquisition of OnTheMarket, we also offer online platforms that manage workflow and marketing for residential real estate agents and brokers and provide portals for homebuyers to view residential property listings.

Industry Overview

The market for real estate information and analysis is vast, based on the variety, volume and value of transactions related to real estate. Each transaction has multiple participants and multiple information requirements, and in order to facilitate transactions, industry participants must have extensive, accurate and current information and analysis. Members of the real estate and related business community require daily access to current data such as space availability, properties for-sale, rental units available, rental rates, vacancy rates, tenant movements, comparable sales, supply, new construction, absorption rates and other important market developments to carry out their businesses effectively. Market research (including historical and forecast conditions) and applied analytics are instrumental to the success of industry participants. There is a strong need for an efficient marketplace, where real estate professionals can exchange information, evaluate opportunities using standardized data and interpretive analyses and interact with each other on a continuous basis.

A large number of parties involved in commercial and residential real estate and the related business community make use of the services we provide in order to obtain information they need to conduct their businesses, including:

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•	Sales and leasing brokers	•	Government agencies
•	Property owners	•	Mortgage-backed security issuers
•	Property managers	•	Appraisers
•	Design and construction professionals	•	Pension fund managers
•	Real estate developers	•	Reporters
•	Real estate investment trust managers	•	Tenant vendors
•	Investment and commercial bankers	•	Building services vendors
•	Mortgage bankers	•	Communications providers
•	Mortgage brokers	•	Insurance companies’ managers
•	Retailers	•	Institutional advisors
•	Hospitality owners	•	Investors and asset managers
•	Real estate agents

The commercial real estate and related business community historically operated in an inefficient marketplace because of the fragmented approach to gathering and exchanging information within the marketplace. Various organizations, including hundreds of brokerage firms, directory publishers and local research companies, collected data on specific markets and developed software to analyze the information they independently gathered. This highly fragmented methodology resulted in duplication of efforts in the collection and analysis of information, excessive internal cost and the creation of non-standardized data containing varying degrees of accuracy and comprehensiveness, resulting in a formidable information gap.

The creation and maintenance of a standardized information platform for commercial real estate requires infrastructure including a standardized database, accurate and comprehensive research capabilities, experienced analysts, easy-to-use technology and intensive participant interaction. By combining our extensive database, researchers, our experienced team of analysts and economists, technological expertise and broad customer base, we believe that we have created such a platform.

The apartment rental advertising industry serves property managers and owners who are tasked with finding renters to occupy vacant apartments, as well as renters who are searching for their next home. Property managers have several options at their disposal, including their own websites, drive-by and outdoor advertising, traditional classified ads, free online listing services, search engine marketing and ILS, like Apartments.com and the network of apartment listing websites we own and operate. Many apartment ILS websites feature only the rental availabilities that larger property owners pay to advertise, resulting in a poor user experience in which the renter’s search criteria return either limited or no results, irrelevant results or stale results that do not represent actual availabilities.

We believe that consumers expect accurate, actionable and comprehensive apartment rental information. Our apartment ILS websites include renter-focused features like the ability to filter search results according to various criteria (e.g., commute time to work); professional images of the properties, including immersive videos and 3-D interactive models; custom neighborhood profiles; and tenant reviews. Our network of apartment listing websites draws on our multifamily database and includes researched and verified information. We proactively gather information on available rentals to improve the accuracy of the listings on our apartment ILS websites, including real time unit-level availability, current pricing and rent specials. We have continually invested in our network to improve the features and services offered to property managers and website users. Recent additions include: dynamic lead forms that provide more information about prospective residents, making rent trends information publicly available, free digital ad retargeting and integrated online rental solutions, including lease applications with tenant credit and background checks. We believe that we have created and maintain easily searchable apartment ILS websites with a comprehensive selection of rentals, information on actual rental availabilities and rents and in-depth data on neighborhoods, as well as easy to use and actionable tools for the rental process.

We believe that consumers expect accurate, actionable and comprehensive homes-for-sale information on a platform that allows collaboration between homebuyers and agents. Our residential websites include homebuyer-focused features like the ability to filter search results according to various criteria (e.g., home features, view and lot type), review rankings of nearby schools and tools to educate consumers on the home buying process. We plan to develop original, media-rich content of neighborhoods, schools, parks and condominium buildings' amenities and common areas to supplement information in agent listings. We are designing tools to facilitate collaboration between homebuyers and agents.

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Strategy

Our strategy is to provide real estate industry professionals and consumers with critical knowledge to explore and complete transactions by offering the most comprehensive, timely and standardized information on real estate and the right tools to be able to effectively utilize that information. Over time, we have expanded, and we continue to expand, our services for real estate information, analytics and online marketplaces in an effort to continue to meet the needs of the industry as it grows and evolves.

Our standardized platform includes the most comprehensive proprietary database of commercial real estate information in the industry; the largest research department in the commercial real estate industry; proprietary data collection, information management and quality control systems; a large in-house product development team; a broad suite of web-based information, analytics and online marketplace services; a large team of analysts and economists; risk management tools; and a large, diverse base of clients. Our database has been developed and enhanced for more than 35 years by a research department that makes daily database updates. In addition to our internal efforts to grow the database, we have obtained and assimilated a number of proprietary databases. Our comprehensive commercial real estate database powers our information services, sources data used in our analytic services and provides content for most of our online marketplace services and our auction platform. Our ability to utilize the same commercial real estate information across our standardized platform creates efficiencies in operations and improves data quality for our customers.

We deliver our comprehensive commercial real estate information content to our customers primarily via an integrated solution of online service offerings that includes information about space available for-lease, comparable sales information, information about properties for-sale, tenant information, internet marketing services, risk management tools, analytical capabilities, information for clients’ websites, information about industry professionals and their business relationships, data integration and industry news. We also operate complementary online marketplaces for commercial and residential real estate listings and apartment rentals, as well as a commercial real estate auction platform. We strive to cross-sell our services to our customers in order to best suit their needs.

We manage and report our business geographically in two operating segments, with our primary areas of measurement and decision-making being North America, which includes the U.S. and Canada, and International, which primarily includes Europe, Asia-Pacific and Latin America. Information about our revenues, long-lived assets and total assets derived from and located in foreign countries is included in Notes 2, 3 and 14 of the Notes to the Consolidated Financial Statements included in Part IV of this Report. Revenues, EBITDA and total assets and liabilities for each of our segments are set forth in Notes 3 and 14 of the Notes to the Consolidated Financial Statements, included in Part IV of this Report. Information about risks associated with our foreign operations is included in “Item 1A. Risk Factors” and “Item 7A. Quantitative and Qualitative Disclosures about Market Risk” in this Report.

CoStar’s Comprehensive Database

We have spent more than 35 years building and acquiring databases of commercial real estate information, which includes information on properties, leasing, sales, comparable sales, tenants and demand statistics, as well as digital images, drone videos and 3-D tours. This highly complex database is comprised of hundreds of data fields, tracking such categories as location, site and zoning information, building characteristics, space and unit characteristics and availability, tax assessments, true ownership, sales and lease comparables, multi-family rents, vacancies and concessions, space requirements, retail locations, mortgage and deed information, for-sale and for-lease listings, fund data, income and expense histories, tenant names, tenant credit scores, view of company locations, lease expirations, contact information, historical trends, forecasts and demographic information. The database also includes building photographs, aerial photographs and videos, 3-D virtual tours, plat maps and floor plans.

CoStar Research

Research Department. Our research professionals undergo an extensive training program so that we can maintain consistent research methods and processes throughout our research department. Our researchers collect and analyze commercial real estate information through phone calls, e-mails and additional research methods including field inspections, public records review, news monitoring, third-party data feeds and user entered content. We have also set up direct feeds from larger apartment sites, owners and brokers, and have put in place an automated system that compiles information sourced from the internet in order to provide the most up-to-date information.

Our researchers are responsible for maintaining the accuracy and reliability of our database information, training our clients to use CoStar Group products and handling their customer service questions, creating a "one touch" approach to customer care. Because of the importance commercial real estate professionals place on our data and our prominent position in the industry,

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many of these professionals routinely take the initiative and proactively report available space and transactions through our online tool, which we refer to as our Marketing Center, or directly to our researchers.

Our field research efforts include physical inspections of properties in order to research new availabilities, find additional property inventory, identify new construction, collect tenant information, verify existing information, photograph properties and create high quality videos of interior spaces (including walk-through videos and 3-D virtual tours), amenities and exterior features of properties. Our field researchers are equipped with high resolution digital cameras and handheld laser instruments to precisely measure buildings and geo-code and position them on digital maps. A typical site inspection of a commercial property consists of photographing the building, capturing interior images, videos and 3-D tours, measuring the building, geo-coding the building, capturing “for-sale” or “for-lease” sign information, counting parking spaces, assessing property condition and construction and gathering tenant information. Field researchers also canvass properties, collecting tenant data suite-by-suite. We also utilize a low-flying airplane and a fleet of drones to conduct aerial research of commercial real estate. We place researchers on the low-flying aircraft to scout new commercial developments and take aerial photographs and videos. Our U.S. drone operators are Federal Aviation Administration certified and trained to capture aerial photographs and videos. Our drone operators in the U.K. and Canada are certified and trained to Civil Aviation Authority and Transport Canada standards, respectively, with a permission for commercial operations pending.

We are leveraging our capabilities developed from our extensive commercial real estate research efforts to produce original, media rich content of neighborhoods, schools, parks and condominium buildings' amenities and common areas for our residential products using professional photographers and a fleet of drones to conduct aerial research of residential real estate.

Data and Image Providers. We license a small portion of our data and images from public record providers and third-party data sources. Licensing agreements with these entities allow us to use a variety of commercial real estate information, including property ownership, tenant information, demographic information, maps, aerial photographs and 3-D virtual apartment tours of apartment communities, all of which enhance our services. These license agreements generally grant us a non-exclusive license to use the data and images in the creation and supplementation of our information, analytics and online marketplaces.

Management and Quality Control Systems. Our research processes include automated and non-automated controls to ensure the integrity of the data collection process. A large number of automated data quality tests check for potential errors, including occupancy date conflicts, available square footage greater than building area, typical floor space greater than building area and expired leases. We also monitor changes to critical fields of information to ensure all information is kept in compliance with our standard definitions and methodology. Our non-automated quality control procedures include:

•Calling our information sources on recently updated properties to re-verify information;

•Reviewing recorded or live listen phone calls (in states where applicable) to ensure information was properly sourced and correctly captured;

•Performing periodic research audits and field checks to determine if we correctly canvassed buildings;

•Providing training and retraining to our research professionals to ensure accurate and standardized data compilation; and

•Compiling measurable performance metrics for research teams and managers for feedback on data quality.

Finally, one of the most important and effective quality control measures we rely on is feedback provided by the commercial real estate professionals using our data every day.

Services

Our portfolio of information, analytics and online marketplaces is branded and marketed to our customers and marketplace end users under the primary brands of CoStar, LoopNet, Apartments.com, Homes.com, OnTheMarket,Ten-X, STR. Land.com and BizBuySell. Our services are accessible via the internet and through our mobile applications. Our services are primarily derived from a database of building-specific information and offer customers specialized tools for accessing, analyzing and using our information. Over time, we have enhanced and expanded, and we expect to continue to enhance and expand, our existing information, analytics and online marketplace services. We have developed and we expect to continue to develop additional services leveraging our database to meet the needs of our existing customers as well as potentially new categories of customers.

Our principal information, analytics and online marketplace services are described in the following paragraphs:

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CoStar

CoStar is our subscription-based integrated platform for commercial real estate intelligence, which includes information about office, industrial, retail, multifamily, hospitality and student housing properties, properties for sale, comparable sales, tenants, space available for lease, industry professionals and their business relationships, industry news and market status and provides lease analysis, risk management, and hospitality benchmarking capabilities. CoStar is our largest service offering in our North America and International operating segments and contains the following tools and features.

•Properties provides a comprehensive inventory of office, industrial, retail, multifamily, hospitality and student housing properties and land. We also provide for-lease and for-sale listings, historical data, property analytics, building photographs, demographics, maps and floor plans. Commercial real estate professionals use this tool to identify available space for-lease, evaluate leasing and sale opportunities, value assets and position properties in the marketplace. Our clients also use this feature to analyze market conditions by calculating current vacancy rates, absorption rates or average rental rates, and forecasting future trends based on user-selected variables with powerful map-based search and reporting capabilities.

•Leasing provides subscribers with comprehensive data on CoStar researched lease transactions and a software tool to capture, manage and maintain their own user-entered lease data, and provides subscribers the ability to analyze this combined lease dataset from an aggregate analytic perspective and generate various reports. In addition, subscribers can incorporate their own data to perform in-depth lease analyses and share those analyses with other subscribers or non-subscribers. This tool can be used to produce an understandable cash flow analysis as well as key metrics about any proposed or existing lease. It combines financial modeling with CoStar’s comprehensive property information, enabling the subscriber to compare lease alternatives, either from a landlord or tenant perspective.

•Sales is a robust database of commercial real estate sales transactions and is designed for professionals who need to research property comparables, identify market trends, expedite the appraisal process and support property valuations. This feature offers subscribers numerous fields of property information, access to support documents (e.g., deeds of trust) for new comparables, demographics and the ability to view for-sale properties alongside sold properties plotted on a map, aerial image or in a table format.

•Tenants is a detailed online business-to-business prospecting and analytics tool. providing commercial real estate professionals with the most comprehensive commercial real estate-related tenant information available in our North American markets. CoStar Tenant profiles tenants occupying space in commercial buildings and provides updates on lease expirations - one of the service’s key features - as well as occupancy levels, growth rates and numerous other facts. This allows users to target prospective clients quickly through a searchable database that identifies only those tenants meeting certain criteria.

•Market Analytics provides owners, investors, brokers, property managers, lenders, appraisers and other commercial real estate professionals the ability to view and report on aggregated market and submarket trends, including leasing, vacancy, rental rates, construction, investment sales activity and overall economic conditions that affect commercial real estate markets. Market Analytics covers all major real estate sectors including office, industrial, retail, multifamily, hospitality and student housing, and provides quantitatively driven and economist curated forecasts of supply, demand, vacancy and rent at the submarket level, and job growth and asset pricing at the market level.

•Public Record provides access to a searchable database of commercially-zoned parcels in the U.S. Users can search for property attributes and sales transaction, loan, lien and tax assessment information. Information in this module is sourced from numerous counties and jurisdictions that provide this data for ownership, title and property tax assessment purposes.

•Benchmarking provides hospitality benchmarking, measuring a hotel’s performance against a self-selected aggregated competitive set. These confidential data reports enable customers to understand their market position based on trends and indices. Reports are provided on a monthly, weekly or daily basis, and provide insights about key metrics such as occupancy, ADR and RevPAR. Benchmarking results are only available to industry participants who provide us with data. These participants are typically hotel brands, third-party management companies and owners.

•Lender provides lenders the tools to manage their loan portfolio and risk. These tools automatically connect the user's portfolio to CoStar's research, market analytics and proprietary COMPASS credit default model, as well as their own data sets, to enable portfolio surveillance, concentration risk monitoring, stress testing and expected credit loss modeling and to support loan originations and underwriting.

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Information Services

We provide real estate and lease management technology solutions, including lease administration, lease accounting and abstraction services, through our CoStar Real Estate Manager service offerings, as well as portfolio and debt analysis, management and reporting capabilities through our CoStar Risk Analytics service offerings. We also provide benchmarking and analytics for the hospitality industry both on a subscription basis and an ad hoc basis. We earn revenue on ad hoc transactions as reports or data are delivered to the customer. We provide information services internationally, through our Business Immo, Belbex and Thomas Daily businesses in France, Spain and Germany, respectively.

•CoStar Real Estate Manager is a real estate lease administration, portfolio management and lease accounting compliance software solution designed for corporate real estate managers, company executives, financial accounting directors, business unit directors, brokers and project managers. CoStar Real Estate Manager helps users connect real estate initiatives with company strategic goals, streamline portfolio operations, reduce occupancy costs with analytics that track location performance against targets and maximize location performance through proactive portfolio management. Additionally, the software is used to help companies manage their lease accounting compliance and reporting requirements.

•CoStar Risk Analytics is a trusted partner to many of the largest commercial real estate lenders and CMBS market participants, providing timely data, advanced analytics, time-proven models and extensive experience to support regulatory examinations, risk management and strategic decision making. CoStar Risk Analytics' COMPASS credit default model has been used by commercial real estate lenders, CMBS participants and regulators for over 15 years to estimate required loss reserves, stress test portfolios, generate risk ratings, calculate capital adequacy, underwrite loans, target lending opportunities and price CMBS bonds. Our clients rely on CoStar Risk Analytics for model validations and reporting to support regulatory examinations. Additionally, CoStar Risk Analytics solutions connect client loan and CMBS loan portfolios to CoStar’s industry-leading commercial real estate data, research, analytics and the COMPASS credit model, updated daily, for more informed decision making, portfolio strategy and surveillance. Clients of CoStar Risk Analytics solutions include many of the largest banks, life insurance companies, asset managers, hedge funds, government agencies and regulators.

Multifamily

Apartments.com, the flagship brand of our network of apartment marketing sites, provides a variety of ad packages and enhancements that allow property managers and owners to fully showcase their apartment community through increased exposure and interactions that allow renters to view, engage and connect with the community. Apartments.com also provides tools to facilitate the rental process, including online tenant applications with background and credit checks and rental payment processing. The Apartments.com Network consists of numerous other apartment marketing sites, including:

•ApartmentFinder provides lead generation, advertising and internet marketing solutions to property managers and owners through its main site, ApartmentFinder.com.

•ForRent.com provides digital advertising through a network of four multifamily websites, which includes ForRent.com, AFTER55.com, CorporateHousing.com and ForRentUniversity.com.

•ApartmentHomeLiving.com provides renters with another national online apartment rental resource that showcases apartments for rent with official prices, pictures, floor plans and detailed information on each apartment.

•Apartamentos.comTM provides Spanish speaking renters with an online apartment rentals resource offered exclusively in Spanish, with the same primary features found on Apartments.com.

•WestsideRentals.com specializes in Southern California real estate rentals.

•Off Campus Partners provides student housing marketplace content and technology to U.S. universities, simplifying the off-campus housing search process for universities, property managers and students.

Our apartment marketing network of subscription-based advertising services provides property owners, professional property management companies and landlords with a comprehensive advertising destination for their available rental units and offers renters a platform for searching for available rentals. Our apartment marketing network draws on and leverages our multifamily database, which contains detailed information on apartment properties and is designed to meet renter preferences and demands, in order to drive traffic to those sites and attract advertisers who prefer to advertise on heavily trafficked apartment websites. Our network of apartment marketing sites provides a comprehensive selection of rentals, information on actual availabilities and rents and in-depth data on neighborhoods, including restaurants, nightlife, history, schools and other

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facts important to renters. To help renters find the information that meets their needs, our sites also offer innovative search tools such as the Polygon Search tool, which allow renters to specifically define the area in which they want to find an apartment and Plan Commute tools, which allow renters to search property listings that meet their transportation needs. We also offer complementary services to the rental industry, including the ability for renters to apply for rentals online and for landlords to receive applications, screen tenants and process rental payments and lease renewals.

LoopNet

LoopNet is the flagship brand in our network of commercial real estate marketing sites, which also includes LoopNet.co.uk, CityFeet.com and Showcase.com. Our LoopNet online marketplace enables commercial property owners, landlords and real estate brokers working on their behalf to advertise properties for-sale or for-lease and to submit detailed information about property listings. Commercial real estate brokers, buyers and tenants use LoopNet extensively to search for available property listings that meet their criteria. LoopNet offers unique, subscription-based advertising solutions for different segments within the industry and delivers value across its constituent networks. The LoopNet network leverages CoStar Group’s commercial real estate database to provide in-depth and accurate information across all commercial property types, including office, industrial, retail, multifamily, specialty, healthcare, hospitality, sports and entertainment, land and residential. Investors and tenants are also able to consume industry news developed by our in-house editorial team.

LoopNet Premium Lister is designed for commercial real estate professionals and other customers who seek the broadest possible exposure for their listings, access to leads lists and advanced marketing and searching tools. LoopNet Premium Lister provides subscribers with the ability to market their listings to all LoopNet.com visitors, as well as numerous other features. LoopNet Premium Lister is available for a quarterly or annual subscription.

LoopNet Diamond, Platinum and Gold Ads are designed for commercial real estate professionals and other customers who seek the broadest possible exposure for their listings, access to leads lists and advanced marketing and searching tools. These LoopNet Ads provide subscribers with full access to our LoopNet network as well as retargeting across a network of prominent sites including the Wall Street Journal, Forbes and Bloomberg. LoopNet Ads are available for a six-month or annual subscription.

Our international subscription-based online marketplaces are Loopnet.co.uk in the U.K., BureauxLocaux in France and Belbex.com in Spain. These marketplaces provide listings of commercial properties for rent and for sale ranging from traditional offices, serviced offices, co-working spaces, hot-desks, retail locations, industrial units, leisure, hotels and warehousing.

Residential

Our Homes.com Network and the acquisition of OnTheMarket have enabled us to expand our offerings to the residential for sale market. Homes.com is a homes for sale listings site that combines our proprietary research with listing information to allow homebuyers an informative and collaborative experience finding homes for sale or lease. Homes.com provides residential real estate professionals subscription-based access to applications that manage residential real estate agent workflow and receives transaction-based revenue for marketing campaigns delivered on third-party platforms. In February 2024, we began selling memberships that allow agents to connect with prospective homebuyers sourced from the agent's own listings. OnTheMarket is a property portal in the U.K. which primarily offers subscriptions-based advertising services to agents.

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Other Marketplaces

Ten-X operates an online auction platform for commercial real estate. Our platform provides brokers, sellers, and buyers access to data-driven technology and marketing tools to expand market visibility and decrease time to close. The platform allows brokers and sellers to onboard assets, evaluate the results of complimentary marketing campaigns and follow up on pre-qualified leads. Buyers can search for properties that meet their investment goals and are given access to market analysis and due diligence documents.

Land.com is the flagship brand in our network of marketplaces for rural lands for-sale sites, which also includes LandsofAmericaTM, LandAndFarmTM and LandWatch®. Sellers pay a fee to list their land for-sale, and interested buyers can search the respective sites' listings.

BizBuySell is the flagship brand in our network of marketplaces for operating businesses and franchises for-sale, which also includes BizQuest and FindaFranchise. Business sellers pay a fee to list their operating businesses for-sale, and interested buyers can search the respective sites' listings for free. The BizBuySell, BizQuest and FindaFranchise Franchise Directories allow interested business buyers to search hundreds of franchise opportunities, and franchisors can list their availabilities in the directory on a cost per lead basis.

We also provide other services that complement those offered by our primary brands. These include: real estate and lease management technology solutions, lease administration, transaction and project management and lease accounting, through our CoStar Real Estate Manager service offerings; market research, consulting and analysis, portfolio and debt analysis and management and reporting capabilities through our CoStar Investment Analysis and CoStar Risk Analytics service offerings; and benchmarking and analytics for the hospitality industry through our STR offerings.

Our services are typically distributed to our clients under subscription-based license agreements that typically renew automatically, a majority of which have a term of at least one year. Upon renewal, many of the subscription contract rates may change in accordance with contract provisions or as a result of contract renegotiations. To encourage clients to use our services regularly, we generally charge a fixed monthly amount for our subscription-based services rather than charging fees based on actual platform usage or number of paid clicks. Depending on the type of service, contract rates are generally based on the number of sites, number of users, organization size, the client's business focus, the client's geographic location, the number and types of services to which a client subscribes, the number of properties a client advertises and the prominence and placement of a client's advertised properties in the search results. Our subscription clients generally pay contract fees on a monthly basis, but in some cases may pay us on a quarterly or annual basis. Our transaction-based services primarily consist of auction fees from our Ten-X online auction platform for commercial real estate, which are generally calculated as a percentage of the final sales price for the commercial real estate property sold and recognized as revenue upon the successful closure of an auction. We generally see higher sales of Apartments.com listing services during the peak summer rental season and higher CoStar sales towards the end of the year; however, sales fluctuate from year-to-year and revenue is not generally seasonal because our services are typically sold on a subscription basis.

Clients

We draw clients from across the real estate and related business community, including real estate brokers, agents, owners, developers, landlords, property managers, financial institutions, retailers, vendors, appraisers, investment banks, government agencies and other parties involved in real estate. For both the years ended December 31, 2023 and 2022, no single client accounted for more than 5% of our revenues.

Sales and Marketing

Our overall sales strategy is to provide optimal service to our existing customers, attract new clients and cross-sell the numerous solutions we offer. Our sales teams sell multiple products and are primarily located in field sales offices throughout the U.S., with others in Canada, the U.K., Spain, France and Germany. Our inside sales teams are largely based in Washington, DC and Richmond, Virginia. Our inside sales professionals actively work lead lists, prospect for new customers and perform in-person and virtual product demonstrations to convey the multiple solutions we offer.

Our local offices typically support field sales and field research operations within the markets in which they operate. This enables our clients to benefit from a local presence. Our field sales force has the primary front-line responsibility for customer service, ensuring client satisfaction and building long-term relationships. Our local offices act as hubs for training, sources of market insight, product feedback sessions and connecting industry participants.

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We actively manage client accounts with frequent meetings, product trainings and updates on new enhancements to our solutions. In 2023, we successfully implemented a number of important sales initiatives focused on selling our products to brokers, property owners and lenders in the U.S. This focus will continue in 2024.

Our primary marketing methods include: in person and virtual service demonstrations; targeted paid digital marketing; retargeting and social media marketing; direct marketing, such as email; communication via our corporate website, campaign-specific websites and news services; participation in virtual trade shows and industry events; Company-sponsored events; client referrals; content marketing including webinars, seminars and white papers and other product-specific company newsletters distributed via email to our clients and prospects.

Comprehensive digital marketing and direct marketing are effective means for us to find prospective clients. Our digital marketing efforts include SEO, targeted paid advertising with major search engines, social media and display advertising on commercial real estate industry news and business websites and mobile applications and our direct marketing efforts include television, radio, out-of-home ads, direct mail and email and, when applicable, make extensive use of our unique, proprietary database. Once we have identified a prospective client, our most effective sales method is a service demonstration. We use various forms of integrated marketing and advertising to build brand awareness, brand identity and reinforce the value and benefits of our services.

We also sponsor and attend local in person and virtual association activities and events, including events for commercial real estate brokers, residential real estate agents, property owners, investors and retail and financial services institutions, and attend or exhibit at virtual industry trade shows and conferences to reinforce our relationships with our core user groups.

To generate brand awareness and site traffic for the Apartments.com network of rental websites, we utilize a multi-channel marketing campaign featuring television and radio ads, online and digital advertising impressions, streaming audio and podcasts, social media, email, public relations and news articles, out-of-home and paid search marketing, all of which are reinforced with substantial SEO efforts. We plan to continue to utilize these marketing methods to generate brand awareness and site traffic for the Apartments.com Network and have implemented similar marketing strategies for LoopNet and Ten-X. To generate brand awareness and site traffic for our residential products, we utilize digital advertising impressions, social media and paid search marketing, all of which are reinforced with SEO efforts. We will continue to work to determine the optimal level of marketing investment for each of these services for future periods.

To encourage clients to use our services regularly, we generally charge a fixed monthly amount for our subscription-based information services rather than fees based on actual system usage. Contract rates for subscription-based services are generally based on the number of sites, number of users, organization size, the client’s business focus, geography and the range of subscription services. Our marketing solutions are priced by exposure levels, the number of properties/spaces for-lease, rent or sale and the market in which they are offered. Listings for customers who purchase packages with the highest level of exposure usually appear first in search results and offer the richest media content and engagement opportunities for tenants searching for space, renters looking for an apartment or investors seeking an opportunity. Our subscription clients generally pay contract fees on a monthly basis, but in some cases may pay us on a quarterly or annual basis.

Expansion and Growth

Acquisitions

We have expanded and continue to expand the coverage and depth of our information, analytics and online marketplace services. In addition to organic growth, we have grown our business through strategic acquisitions. We acquired Homes.com, BureauxLocaux, Business Immo and OnTheMarket in May 2021, October 2021, April 2022 and December 2023, respectively. We continue to integrate our recent acquisitions and the services they offer into our CoStar network.

See Notes 5 and 9 of the Notes to the Consolidated Financial Statements, included in Part IV of this Report, for further discussion of these acquisitions.

Development, Investments and Expansion

We plan to continue to invest in our business and our services, evaluate strategic growth opportunities and pursue our key priorities as described below in Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations. We are committed to supporting, improving and enhancing our information, analytics and online marketplace solutions, including expanding and improving our offerings for property owners, property managers, brokers, agents, buyers, commercial tenants and residential renters and homebuyers. We expect to continue our software development efforts to improve existing services, introduce new services, integrate and cross-sell services and expand and develop supporting technologies for

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our research, sales and marketing organizations. We reevaluate our priorities on a regular basis and may reevaluate our priorities as economic conditions continue to evolve.

We evaluate potential changes to our service offerings from time to time in order to better align the services we offer with customers’ needs. Further, in some cases, when integrating and coordinating our services and assessing industry and client needs, we may decide to combine, shift focus from, de-emphasize, phase out or eliminate a service that, among other things, overlaps or is redundant with other services we offer. In the event that we eliminate or phase out particular service offerings, we may experience reduced revenues and earnings. The decision to eliminate or phase out a service offering may also ultimately result in increased revenues and earnings from sales of other services we offer in lieu of the eliminated or phased out services. However, we cannot predict with certainty the amount or timing of any reductions in revenues and earnings or subsequent increases in revenues and earnings, if any, resulting from the elimination or phasing out of any service offering.

We believe that our integration efforts and continued investments in our services, including acquisitions and expansion of our existing service offerings, have created a platform for long-term revenue growth. We expect these investments to result in further penetration of our subscription-based services and the successful cross-selling of our services to customers in existing markets.

We have invested in the expansion and development of our field sales force to support the growth and expansion of our company and our service offering, and plan to continue to invest in, evaluate and strategically position our sales force as we continue to develop and grow. In addition, we continue to invest in marketing our services, as well as in our research operations to support continued growth of our information and analytics offerings to meet the growing content needs of our clients. We plan to continue to utilize multi-channel marketing campaigns and to work to determine the optimal level of marketing investments for our services for future periods. While we believe the investments we make in our business create a platform for growth, those investments may reduce our profitability and adversely affect our near-term financial position.

Proprietary Technology

Our information technology professionals focus on developing new services and features for our customers, improving and maintaining existing services, integrating our current services, securing our comprehensive database of commercial real estate information and delivering research automation tools that improve the quality of our data and increase the efficiency of our research analysts.

Our information technology team is responsible for developing, improving and maintaining our information, analytics and online marketplace services. Our information technology team is also responsible for developing the infrastructure necessary to support our business processes, comprehensive database of commercial real estate information, analytics and online marketplaces and extensive image library. The team implements technologies and systems that introduce efficient workflows and controls designed to increase the production capacity of our research teams and improve the quality of our data. Over the years, the team has developed data collection and quality control mechanisms that we believe are unique within the commercial real estate industry. The team continues to develop and modify our enterprise information management system that integrates our sales, research, field research, customer support and accounting information. We use this system to maintain our commercial real estate research information, manage contacts with the commercial real estate community, provide research workflow automation and conduct daily automated quality assurance checks. In addition, our information technology team has also developed fraud-detection technology to detect and prevent unauthorized access to our services. To supplement the measures we take to prevent misuse of our information, we added state of the art adaptive authentication technology to the login process of our CoStar product.

Our information technology professionals maintain the servers and network components necessary to support our services and research systems. Our core services are delivered from multiple data centers and cloud-based computing platforms to support uninterrupted service for our customers and are continually monitored to ensure fast and reliable customer access, to protect against unauthorized intrusions and to detect vulnerabilities.

Our comprehensive data protection policy provides for use of secure networks, strong passwords and dual factor authentication systems, encrypted data fields, end-to-end encryption, endpoint detection and response systems and services, security information and event management systems, off-site storage, cloud services, end user and developer security training, multilayered anti-phishing malware and spam protections and other protective measures in an effort to ensure the availability and security of all core systems.

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Competition

The market for information, analytics and online marketplaces generally is competitive and extremely dynamic. In the commercial real estate, apartment rentals and home for sale industries, we believe the principal competitive factors affecting these services and providers are:

•Quality and depth of the underlying databases;

•Quality and quantity of leads and, for multifamily, leases delivered;

•Ease of use, flexibility and functionality of the software;

•Intuitiveness and appeal of the user interface;

•Timeliness of the data, including listings;

•Breadth of geographic coverage and services offered;

•Completeness and accuracy of content;

•Client service and support;

•Perception that the service offered is the industry standard;

•Price;

•Effectiveness of marketing and sales efforts;

•Proprietary nature of methodologies, databases and technical resources;

•Vendor reputation;

•Brand loyalty among customers; and

•Capital resources.

We compete directly and indirectly for customers with the following categories of companies:

•Online marketing services, internet listing services, mobile software applications or data exchanges targeted to commercial real estate brokers, buyers and sellers of commercial real estate properties, insurance companies, mortgage brokers and lenders, such as Reed Business Information Limited and its Estates Gazette and Radius Data Exchange products, SquareFoot, officespace.com, Brevitas, Catylist & Commercial Exchange (part of Moody's), Altus Group & Commercial Property Search (part of Reonomy), Digsy, Quantum Listing, RealNex MarketPlace, Rofo, CIMLS, CompStak, Rightmove, Yardi (CommercialEdge), CREXi, TotalCommercial.com, DebtX, Real Capital Markets, VTS, TenantBase and Spacelist;

•Publishers and distributors of information, analytics and marketing services, including regional providers and national print publications, such as CBRE Economic Advisors, Marshall & Swift, REIS Network (part of Moody's), Real Capital Analytics, Real Capital Markets, Reonomy, Yardi Matrix, RealPage and its Axiometrics business, Altus Insight and Altus RealNet (Canada);

•Search engines, internet listing services and mobile software applications featuring apartments for rent, such as Google, Bing, Facebook Marketplace, ApartmentGuide.com, Rent.com, Rentals.com, Zillow Rentals, Trulia Rentals, StreetEasy, HotPads.com, MyNewPlace.com, Zumper, Craigslist, ApartmentList.com, Move.com, Realtor.com, RentCafe.com, RentHop, RentBerry, ApartmentRatings, Nooklyn, Home Finder and Rentable;

•Search engines, internet listing services and mobile software applications featuring homes for sale, such as Google, Bing, Facebook Marketplace, Zillow, Trulia, Redfin, Realtor.com, Move.com, Craigslist, RealtyTrac, MLS.com, Home Finder, For Sale by Owner, Auction.com, Rightmove and Zoopla, as well as agent marketing platforms and workflow providers;

•Hospitality benchmarking and analytics services, such as Lodging Econometrics, Kalibri Labs, Amadeus, HotStats, Shiji Group (SnapShot), Benchmarking Alliance and Lodging Analytics Research & Consulting (LARC);

•Online and mobile software application providers in the residential real estate industry, including Zillow, Redfin, Realtor.com and Rocket Mortgage, as well as agent marketing platforms and workflow providers;

•In the commercial real estate market, locally controlled real estate boards, exchanges or associations sponsoring commercial property listing services and the companies with whom they partner, such as Catylist, the National Association of Realtors, CCIM Institute, Society of Industrial and Office Realtors, the Commercial Association of Realtors Data Services and AIR CRE;

•Real estate portfolio management software solutions, such as Cougar Software, MRI Software, Altus, RealPage, AppFolio and SiteCompli;

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•Real estate lease management and administration software solutions, such as Accruent, Tririga, Manhattan Software, Tango Analytics, Lease Accelerator, Visual Lease, Sequnetra, Lease Harbor and AMT Direct;

•Commercial real estate auction platforms such as CREXi, Marketplace, by RealINSIGHT and RCM Lightbox;

•In-house research departments operated by commercial real estate brokers; and

•Public record providers.

As markets for information, analytics and online marketplaces develop, additional competitors (including companies that could have greater access to data, financial, product development, technical, analytic or marketing resources than we do) may enter a market and competition may intensify. For example, a company like Google, which has a far-reaching web presence and substantial data aggregation capabilities, could enter the commercial real estate marketing arena. A company like Zillow, which already has a presence in residential real estate and the apartment rentals industry, could use its resources to further expand in the online apartment rentals industry creating greater competition among internet listing services for the marketing budgets of property managers and property owners. While we believe that we have successfully differentiated ourselves from existing competitors, current or future competitors could materially harm our business. We may also enter markets where incumbent players have greater name recognition and resources, creating challenges as we work to expand.

Proprietary Rights

To protect our proprietary rights in our methodologies, database, software, trademarks and other intellectual property, we depend upon a combination of:

•Trade secret, misappropriation, unfair competition, copyright, trademark, computer fraud, database protection and other laws;

•Registration of copyrights and trademarks;

•Nondisclosure, and other contractual provisions with employees and consultants;

•License agreements with customers;

•Patent protection; and

•Technical measures.

We seek to protect our software’s source code, our database and our photography as trade secrets and under copyright law. Although copyright registration is not a prerequisite for copyright protection, we have filed for copyright registration for many of our databases, photographs, software and other materials. Under current U.S. copyright law, the arrangement and selection of data may be protected, but the actual data itself may not be. Certain U.K. database protection laws provide additional protections for our U.K. databases. We license our services under license agreements that grant our clients non-exclusive, non-transferable rights. These agreements restrict the disclosure and use of our information and prohibit the unauthorized reproduction or transfer of any of our proprietary information, methodologies or analytics.

We also attempt to protect our proprietary databases, our trade secrets and our proprietary information through confidentiality and agreements with our employees and consultants. Our services also include technical measures designed to detect, discourage and prevent unauthorized access to and/or copying of our intellectual property. We have established an internal antipiracy team that uses fraud-detection technology to continually monitor use of our services to detect and prevent unauthorized access, and we actively prosecute individuals and firms that engage in this unlawful activity.

We maintain U.S. and international trademark registrations for CoStar Group’s core service names and proactively file U.S. and international trademark applications covering our new and planned service names. We own U.S. federally registered trademarks for our brands and services including CoStar®, CoStar Property®, CoStar COMPS®, CoStar Lease Analysis®, LoopNet®, Showcase.com®, CityFeet.com®, Apartments.com®, Homes.com®, Land.com®, and Ten-X®, among many others. In the U.S., trademarks are generally valid so long as they are in use and are capable of indicating CoStar Group as the source of services. We consider our trademarks in the aggregate to constitute a valuable asset.

In addition, we maintain a patent portfolio that protects certain of our systems and methodologies. We currently have six patents in Canada, which expire in 2033 (1 patent), 2035 (2 patents) and 2036 (3 patents), covering, among other things, certain features of our field research methodologies and user interface features, and 12 patents in the U.S. which expire in, 2025 (1 patent), 2032 (2 patents), 2036 (4 patents), 2037 (4 patents) and 2038 (1 patent), covering, among other things, certain features of our field research methodologies and user interface feature. We regard the rights protected by our patents as valuable to our business, but do not believe that our business is materially dependent on any single patent or portfolio of patents as a whole.

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Human Capital Resources

As of January 31, 2024, we employed 6,152 employees. U.S.-based employees represent approximately 86% of the overall employee population, followed by 12% in European, Asia-Pacific and Latin American countries and 2% in Canadian provinces. None of our employees are represented by a labor union. We have experienced no work stoppages. As is common with many German companies, employees in our German subsidiary, Thomas Daily GmbH, have elected five fellow employees to form a Works Council, which represents our employees at the location. The Works Council has certain co-determination rights and rights to receive information from us and engage us in discussions under applicable law. BureauxLocaux, in France, has a Social and Economic Committee, which is an employee representative body.

Our human resources and recruiting teams work in partnership with business leaders, using a robust process to attract a diverse slate of candidates to fill vacancies and contribute to our growth, including our Careers page on our corporate website, employee referral program, social media and digital platforms, direct outreach, partnerships with commercial real estate industry groups and universities and specific partnerships and programs. The development and retention of our employees is critical to our success. To support career development, we offer on-demand and in-person training programs to new hires, managers, and leaders. We also offer a mentoring program, which pairs employees seeking mentorship with more experienced colleagues.

To assess employee engagement, we partner with a survey vendor to survey employees annually. Insights and results gathered from the survey are shared with our leadership, managers and employees and help to inform our human resources program strategy each year. We believe that diverse teams deliver better and more innovative solutions. The diversity of thought that comes from different perspectives and backgrounds allows us to deliver cutting edge research and technology solutions that best serve our customers. We have a dedicated Diversity, Equity and Inclusion team that is tasked with developing topical programming, communications and training including, but not limited to, celebrations of various heritage months and oversight of our employee resource groups, which create avenues for mentoring and professional development within these groups as well as education and awareness across the organization.

We provide competitive pay and benefits to attract and retain high-quality talent. In addition to base salaries, compensation may include annual bonuses, commissions, and equity awards. Employees may also participate in an Employee Stock Purchase Plan and a 401(k) Plan with a company match. Our comprehensive set of health and wellness benefits are affordable, high quality and valuable to employees and their families. Employees have multiple choices for health plans, access to vision and dental benefits and may participate in our employee wellness program as well as our employee assistance program. Additional benefits include paid time off, parental bonding leave, college savings benefits, tuition reimbursement, company-subsidized commuter benefits and access to mental health, tax, and legal services.

Available Information

Our investor relations internet website is http://www.costargroup.com/investors. The reports we file with or furnish to the SEC, including our annual report, quarterly reports and current reports, as well as amendments to those reports, are available free of charge on our internet website as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. The SEC maintains an internet site that contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC at http://www.sec.gov.

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Item 1A.    Risk Factors

Risks related to our business

Our revenues and financial position will be adversely affected if we are not able to attract and retain clients. Our success and revenues depend on attracting and retaining subscribers to our information, analytics and online marketplace services. Our subscription-based services generate the largest portion of our revenues. Our revenue may not grow, or could decrease, if we cannot attract new customers, continue to keep our cancellation rate low and continue to sell new services to our existing customers. We may not be able to continue to grow our customer base, keep the cancellation rate low or sell new services to existing customers as a result of several factors, including, continuing global economic and geopolitical volatility, economic pressures and the impact of inflation on our costs and on customer spending; the business failure of current clients; customer decisions that they do not need our services or to use alternative services; customers’ and potential customers’ budgetary constraints; consolidation in the real estate and/or financial services industries; data quality; technical problems; competitive pressures; or devaluation of the local currencies of international customers relative to the U.S. dollar which impairs the purchasing power of such customers. We compete against many other real estate information, analytics and marketing service providers for business. If clients cancel services or decide not to renew their subscription agreements and we do not sell new services to our existing clients or attract new clients, then our renewal rate, net new bookings and revenues may decline or fail to meet expectations.

We may not be able to successfully develop and introduce new or upgraded information, analytics and online marketplace services that are attractive to our users and advertisers or successfully combine or shift focus from current services with less demand, which could decrease our revenues and our profitability. Our future business and financial success will depend on our ability to continue to anticipate the needs of customers and potential customers and to successfully introduce new and upgraded services, including services that make our marketplaces useful for users and attractive to advertisers. To be successful, we must be able to quickly adapt to changes in the industry, as well as rapid technological changes, by continually enhancing our information, analytics and online marketplace services. As a result, we must continually invest resources in research and development to improve the appeal and comprehensiveness of our services and effectively incorporate new technologies.

Developing new services and upgrades to services, as well as integrating and coordinating current services, imposes heavy burdens on our systems department, product development team, management and researchers. The processes are costly, and our efforts to develop, integrate and enhance our services may not be successful. In addition, launching and selling a new or upgraded service puts additional strain on our sales and marketing resources. If we are unsuccessful in obtaining greater market share or in obtaining widespread adoption of new or upgraded services, we may not be able to offset the expenses associated with the development, launch and marketing of the new or upgraded service, which could have a material adverse effect on our financial results. For example, we have and will continue to invest significantly in developing our marketplaces and content and, to generate brand awareness and site traffic, we have and will continue to invest significant resources in multi-channel marketing campaigns for select marketplaces. If these development efforts and marketing campaigns do not increase brand awareness, site traffic, subscriptions for marketplaces services and/or revenues, the cost of these campaigns could have an adverse effect on our financial results.

In addition, as we integrate acquired businesses, we continue to assess which services we believe will best meet the needs of our customers. If we eliminate or phase out a service and are not able to offer and successfully market and sell an alternative service, our revenues may decrease, which could have a material adverse effect on our results of operations.

We may not be able to compete successfully against existing or future competitors in attracting advertisers, which could harm our business, results of operations and financial condition. We compete to attract advertisers. Our competitors may have greater brand recognition or more direct sales personnel than we have and may generate more web traffic than we do, which may provide them with competitive advantages. To compete successfully for advertisers, we must continue to invest resources in developing our advertising platform and proving the effectiveness and relevance of our advertising services. Pressure from competitors seeking to acquire a greater share of our advertisers’ overall marketing budget could adversely affect our pricing and margins, lower our revenue and increase our research and development and marketing expenses. If we are unable to compete successfully against our existing or future competitors, our business, results of operations or financial condition could be adversely affected.

Competition could render our services uncompetitive and reduce our profitability. The markets for information systems and services and for online marketplaces in general are highly competitive and rapidly changing. Competition in these markets may increase further if economic conditions or other circumstances cause customer bases and customer spending to decrease and service providers to compete for fewer customer resources. Our existing or future competitors may have greater name recognition, larger customer bases, better technology or data, lower prices, easier access to data, greater user traffic or greater financial, technical or marketing resources than we have to provide services that users might view as superior to our offerings. Competitors may introduce different solutions that attract users away from our services or provide solutions similar to ours that

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have the advantage of better branding or marketing resources. Our competitors may be able to undertake more effective marketing campaigns, obtain more data, adopt more aggressive pricing policies, make more attractive offers to potential employees, subscribers, advertisers, distribution partners and content providers or may be able to respond more quickly to new or emerging technologies or changes in user requirements. Increased competition could result in lower revenues and higher expenses, which would reduce our profitability.

Our operating results and revenues are subject to fluctuations and our quarterly financial results may be subject to market cyclicality, each of which could negatively affect our stock price. The real estate market may be influenced by general economic conditions, economic cycles, changes in interest rates, seasonality and many other factors, which in turn may impact our financial results. The different sectors of the large and fragmented industry, such as office, industrial, retail, multifamily, single family and others, are influenced differently by different factors, and have historically moved through economic cycles with different timing. As such, it is difficult to estimate the potential impact of economic cycles and conditions or seasonality from year-to-year on our overall operating results. For example, we generally see higher sales of Apartments.com listing services during the peak summer rental season and higher CoStar sales towards the end of the year; however, sales fluctuate from year-to-year and may fluctuate more widely when there are changes in general economic conditions or the industry.The timing of widely observed holidays and vacation periods, particularly slowdowns during the end-of-year holiday period, and availability of real estate agents and related service providers during these periods, could significantly affect our quarterly operating results during that period. If we are unable to adequately respond to economic, seasonal or cyclical conditions, our revenues, expenses and operating results may fluctuate from quarter to quarter. Our operating results, revenues and expenses may fluctuate for many reasons, including those described in this paragraph and below:

•Rates of subscriber adoption and retention;

•Timing of our annual sales conference or significant marketing events;

•Changes in our pricing strategy and timing of changes;

•The timing and success of new service introductions and enhancements;

•The shift of focus from certain services we offer or the phase out of services that overlap or are redundant with other services we offer;

•The amount and timing of our expenses and capital expenditures;

•The amount and timing of non-cash stock-based charges;

•Acquisition-related costs or impairment charges associated with investments and acquisitions;

•Competition;

•Changes or consolidation in the real estate industry;

•Interest rate fluctuations;

•Execution of our expansion and integration plans;

•The development of our sales force;

•Foreign currency exchange rate fluctuations;

•Inflation; and

•Changes in client budgets.

These fluctuations could negatively affect our results of operations during the period in question and/or future periods or cause our stock price to decline. In addition, changes in accounting policies or practices may affect our level of net income. Fluctuations in our financial results, revenues and expenses may cause the market price of our common stock to decline.

Global economic uncertainties and downturns or a downturn or consolidation in the real estate industry may decrease customer demand for our services and adversely affect our business and results of operations. Global economic uncertainties or downturns could adversely affect our business and results of operations, including financial and credit market fluctuations, changes in economic policy, increased inflation and responsive actions, rising interest rates or a period of elevated interest rates, labor shortages, supply chain disruptions, trade uncertainty, political unrest, geographical instability or other impacts from the macroeconomic environment. These macroeconomic conditions could cause a decrease in customer spending and negatively affect the rate of growth of our business. The real estate market may be adversely impacted by many different factors, including lower than expected job growth or job losses resulting in reduced real estate demand; reduced real estate demand due to continued remote work policies or a period of elevated interest rates; rising interest rates, inflation, slowing transaction volumes and other macroeconomic trends that negatively impact investment returns; excessive speculative new construction in localized markets resulting in increased vacancy rates and diminished rent growth; unanticipated disasters or global health events; and other adverse events such as decreased growth in the working age population resulting in reduced demand for all types of real estate. In response to concerns over inflation, the U.S. Federal Reserve raised interest rates in each quarter of 2022 and the first, second and third quarters 2023. A downturn in the real estate market, including as a result of increased interest rates or a decline in leasing activity and absorption rates may affect our ability to generate revenues and may lead to more cancellations by our current or future customers, either of which could cause our revenues or our revenue growth rate to decline and reduce our profitability. A depressed real estate market has a negative impact on our core customer base, which could decrease demand for

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our information, analytics and online marketplaces. Also, companies in this industry may consolidate, often in order to reduce expenses. Consolidation, or other cost-cutting measures by our customers, may lead to cancellations of our information, analytics and online marketplace services by our customers, reduce the number of our existing clients, reduce the size of our target market or increase our clients’ bargaining power, all of which could cause our revenues to decline and reduce our profitability. If cancellations, reductions of services and failures to pay increase, and we are unable to offset the resulting decrease in revenues by increasing sales to new or existing customers, our revenues may decline or grow at lower rates.

If we are unable to hire qualified persons for, or retain and continue to develop, our sales force, or if our sales force is unproductive, our revenues could be adversely affected. In order to support revenues and revenue growth, we need to continue to develop, train and retain our sales force. Our ability to build and develop a strong sales force may be affected by a number of factors, including: our ability to attract, integrate and motivate sales personnel; our ability to effectively train our sales force; the ability of our sales force to sell an increased number and different types of services; our ability to manage effectively an outbound telesales group; the length of time it takes new sales personnel to become productive; the competition we face from other companies in hiring and retaining sales personnel; our ability to effectively structure our sales force; and our ability to effectively manage a multi-location sales organization, including field sales personnel. If we are unable to hire qualified sales personnel and develop and retain our sales force, including sales force management, or if our sales force is unproductive, our revenues or growth rate could decline and our expenses could increase. We may face additional challenges in hiring employees in an increasingly competitive job market.

Our business depends on retaining and attracting highly capable management and operating personnel. Our success depends in large part on our ability to retain and attract management and operating personnel, including our President and Chief Executive Officer, Andrew Florance, and our other officers and key employees. Our business requires highly skilled technical, sales, management, web product and development, marketing and research personnel, who are in high demand and are often subject to competing offers. The measures we use to attract and retain key personnel may not be enough to attract and retain the personnel we need or to offset the impact on our business of the loss of the services of Mr. Florance or other key officers or employees. If Mr. Florance were to become unavailable for any reason, there could be a material adverse impact on our operations. The loss of other key personnel, including members of management as well as key technology, product development, and marketing personnel, could also disrupt our operations and have an adverse effect on our business.

Our internal and external investments may place downward pressure on our operating margins. To increase our revenue growth, we continue to invest significantly in our business, including internal investments in product and content development to expand the breadth and depth of services we provide to our customers and external investments in sales and marketing to generate brand awareness and traffic to our websites. Our operating margins may experience downward pressure in the short term as a result of these investments. Furthermore, our investments may not produce the expected results. If we are unable to successfully execute our investment strategy, we may experience decreases in our revenues or revenue growth rate and operating margins.

Introducing new products may be difficult and expensive. If we are unable to do so successfully, our brands may be adversely affected, and we may not be able to maintain or grow our current revenue and profit levels. In February 2024 we launched our Homes.com monetization strategy. We have incurred, and expect to continue to incur, significant costs to develop and market Homes.com. If we are unable to attract and retain agent subscribers and consumers, we may not be able to execute our growth plans or recognize a return on the investments we have made into Homes.com. Failure to gain market acceptance for Homes.com could impede our ability to maintain or grow current revenue levels or reduce profits for our other brands, adversely affect the image of our brands, erode our competitive position, and result in long-term harm to our business and financial results. Extrapolations annualizing initial sales results may differ materially from actual results realized in future periods and may not take into account other future market conditions that may negatively affect those results.

We may be unable to increase awareness of our brands, including CoStar, LoopNet, Apartments.com, Homes.com Land.com, BizBuySell, STR, Ten-X, and OnTheMarket, which could adversely affect our business. We rely heavily on our brands, which we believe are key assets of our company. Awareness and differentiation of our brands are important for attracting and expanding the number of users of, and subscribers to, our online marketplaces, such as the LoopNet Network, the Apartments.com Network, our Homes.com and OnTheMarket residential marketplaces, the Land.com Network and our CoStar Showcase. We continue to invest significantly in sales and marketing as we seek to grow the numbers of users of, subscribers to and advertisers on, our marketplaces. Our methods of advertising may not be successful in increasing brand awareness or, ultimately, be cost-effective. If we are unable to maintain or enhance user and advertiser awareness of our brands, or if we are unable to recover our marketing and advertising costs through increased usage of our services and increased advertising on our websites, our business, results of operations and financial condition could be adversely affected.

If internet search engines do not prominently feature our websites on the search engine results page, traffic to our websites would decrease and, if we are unable to maintain or increase traffic to our marketplaces, our business and operating results could be adversely affected. Our ability to generate revenues from our marketplace business depends, in part, on our ability to

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attract users to our websites. Google, Bing, DuckDuckGo and other internet search engines drive traffic to our websites, including CoStar.com, the LoopNet Network, the Apartments.com Network, our Homes.com and OnTheMarket residential marketplaces, the Land.com Network, Ten-X.com and BizBuySell. For example, when a user enters in a search query for an apartment building name or address into an internet search engine, the internet search engine’s ranking of our Apartments.com or Homes.com webpages will determine how prominently such webpages are displayed on the search engine results page. Our ability to maintain prominent search result rankings and positioning is not entirely within our control. Our competitors’ SEO and SEM efforts may result in webpages from their websites receiving higher rankings than the webpages from our websites. Internet search engines could revise their algorithms and methodologies in ways that would adversely affect our search result rankings. Internet search engine providers could form partnerships or enter into other business relationships with our competitors resulting in competitors’ sites receiving higher search result rankings. Internet search engines are increasingly placing alternative search features (such as featured snippets, local map results and other immersive experiences) on the search engine results page above or more prominently than search engine results. If our search result rankings are not prominently displayed, traffic to our websites may decline which could slow the growth of our user base. Our websites have experienced fluctuations in search result rankings in the past and we anticipate similar fluctuations will occur in the future. If we experience a material reduction in the number of users directed to our websites through internet search engines or otherwise fail to maintain or increase traffic to our marketplaces, our ability to acquire additional subscribers or advertisers and deliver leads to and retain existing subscribers and advertisers could be adversely affected. As a result, our business, results of operations and financial condition could be adversely affected. Increases in our operating expenses could negatively impact our operating results if we are unable to generate more revenues through increased sales of subscriptions to our marketplace products. Additionally, the methods, including Google Analytics, that we use to measure unique visitors to our portals may misstate the actual number of unique persons who visit our network of mobile applications and websites for a given month or may differ from the methods used by competitors, which may impact the comparability of unique visitors between companies. Additionally, the methods, including Google Analytics, that we use to measure unique visitors to our portals may misstate the actual number of unique persons who visit our network of mobile applications and websites for a given month or may differ from the methods used by competitors, which may impact the comparability of unique visitors between companies.

If real estate professionals or other advertisers reduce or cancel their advertising spending with us and we are unable to attract new advertisers, our operating results would be harmed. Our marketplace businesses, including the LoopNet Network, the Apartments.com Network, our Homes.com and OnTheMarket residential marketplaces, CoStar Showcase and the Land.com Network, depend on advertising revenues generated primarily through sales to persons in the real estate industry, including broker, agents, property managers and owners, real estate agents, and other advertisers. Our ability to attract and retain advertisers, and ultimately to generate advertising revenue, depends on a number of factors, including:

•Increasing the number of unique visitors to, and users of, our websites and mobile applications;

•The quantity and quality of the leads that we provide to our advertisers;

•The success of any marketing and product development efforts directed at attracting additional users and advertisers to our marketplaces;

•Keeping pace with changes in technology and with our competitors; and

•Offering an attractive return on investment to our advertisers for their advertising dollars spent with us.

Further, with respect to the Apartments.com Network and LoopNet Networks, our ability to attract and retain advertisers also depends on the current apartment rental market and apartment vacancy rates and commercial rental market and vacancy rates, respectively. If vacancy rates are too high or too low, advertisers may not need to utilize our marketplace services.

Many of the advertisers who advertise on our marketplaces do not have long-term contracts. These advertisers could choose to modify or discontinue their relationships with us with little or no advance notice. As existing subscriptions for advertising expire, we may not be successful in renewing these subscriptions or securing new subscriptions. We may not succeed in retaining existing advertisers’ spending or capturing a greater share of such spending if we are unable to convince advertisers of the effectiveness of our services as compared to alternatives. In addition, future changes to our pricing methodology for advertising services may cause advertisers to reduce or discontinue their advertising with us. If current advertisers reduce or end their advertising spending with us and we are unable to attract new advertisers, our advertising revenues and business, results of operations and financial condition could be adversely affected.

If we are not able to successfully identify, finance, integrate and/or manage costs related to acquisitions, our business operations and financial position could be adversely affected. We have expanded our markets and services in part through acquisitions of complementary businesses, services, databases and technologies, and expect to continue to do so in the future. Our acquisition strategy depends on our ability to identify, and the availability of, suitable acquisition candidates. We are likely to incur costs in connection with proposed acquisitions, but may ultimately be unable or unwilling to consummate any particular proposed transaction for various reasons. For example, in 2021, the FTC withheld approval for our proposed acquisition of RentPath, the purchase agreement was subsequently terminated and we incurred a termination fee of $52 million.

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We are also likely to incur severance costs and other integration costs post-acquisition. Costs in connection with acquisitions and integrations may be higher than expected and could adversely affect our financial condition, results of operations or prospects of the combined business. In addition, acquisitions involve numerous risks, including risks that we will not be able to realize or capitalize on synergies created through combinations; manage the integration of personnel and products or services; manage the integration of acquired infrastructure and controls; control potential increases in operating costs; manage geographically remote operations; maintain management’s attention on other business concerns and avoid potential disruptions in ongoing operations during an acquisition process or integration efforts; successfully enter markets and sectors in which we have either limited or no direct experience, including foreign markets whose practices, regulations or laws may pose increased risk; and retain key employees, clients or vendors and other business partners of the acquired companies. We may not successfully integrate acquired businesses or assets and may not achieve anticipated benefits of an acquisition, including expected synergies. For example, we may be unable to fully integrate BureauxLocaux, Business Immo and OnTheMarket with CoStar Group when and as expected.

We were previously subject to a consent order agreed to among the FTC staff, CoStar Group and LoopNet on April 17, 2012 in connection with the LoopNet merger. This consent order expired in August 2022, but if we become subject to similar orders in the future, compliance with such orders could prevent us from closing certain acquisitions or add significant time and cost to such acquisitions, ultimately making an acquisition prohibitive or preventing us from realizing its anticipated benefits.

External factors, such as compliance with laws and regulations and shifting market preferences, may also impact the successful integration of an acquired business. An acquired business could strain our system of internal controls and diminish its effectiveness. Acquisitions could result in dilutive issuances of equity securities, the incurrence of debt and substantial amortization expenses of other intangible assets. We may be unable to obtain financing on favorable terms, or at all, if necessary to finance future acquisitions, making it impossible or more costly to complete future acquisitions. If we are able to obtain financing, the terms may be onerous and restrict our operations. Further, certain acquisitions may be subject to regulatory approval, which can be time-consuming and costly to obtain or may be denied, as in the case of RentPath. If regulatory approval is obtained, the terms of any such approval may impose limitations on our ongoing operations or require us to divest assets or lines of business. If regulatory approval is denied, we may incur significant, additional costs payable to an acquisition target as a result of failure to close the transaction. For example, we incurred a termination fee of $52 million in connection with termination of the RentPath purchase agreement. Significant break-up fees incurred in the future may adversely affect our results of operations and financial condition.

As a result of our acquisitions, we had approximately $2.7 billion of goodwill and intangibles as of December 31, 2023. Future acquisitions may increase this amount. If we are required to recognize goodwill and intangibles impairment charges in the future, this would negatively affect our financial results in the periods of such charges, which may reduce our profitability.

Cyberattacks and security vulnerabilities could result in serious harm to our reputation, business and financial condition. Our business relies on IT Systems and involves the generation, collection, storage, processing and transmission of Confidential Information, including personal information and proprietary business information, by us and by third-party providers we rely on. We own and manage IT Systems but also rely on third-party managed IT Systems and a broad array of third-party products and services to support our business operations. An increasing number of organizations, including large merchants, businesses, technology companies and financial institutions, as well as government institutions, have disclosed security incidents, disruptions to, and breaches of their or third-party providers’ IT Systems, some of which have involved sophisticated and highly targeted attacks, including on websites, mobile applications and infrastructure, following a trend of cyberattacks increasing in frequency and magnitude on a global basis.

Our IT Systems, or those of third parties on which we rely, may be disrupted or damaged and our Confidential Information may be compromised, corrupted, lost or stolen. The tools and techniques (including artificial intelligence) used to obtain unauthorized, improper or illegal access to a target’s systems, data or customers’ data, disable or degrade services, or sabotage systems are constantly evolving and have become increasingly complex and sophisticated. It may be difficult to detect, investigate or remediate such cyber attacks quickly and such attacks often are not recognized or detected until after they have been launched against a target. We expect that unauthorized parties will continue to attempt to gain access to or disrupt our IT systems or facilities through various means, including hacking into IT Systems or facilities or those of our customers or vendors, malware (including ransomware) or attempting to fraudulently induce (for example, through spear phishing attacks or social engineering) our employees, customers, vendors or other users of IT Systems into disclosing access credentials or other sensitive information, which may in turn be used to access our IT Systems.

Numerous and evolving cybersecurity threats, including from diverse threat actors, such as state-sponsored organizations, opportunistic hackers and hacktivists, as well as through diverse attack vectors, such as advanced cyberattacks, phishing, social engineering schemes, malware (including ransomware), malfeasance by insiders, human or technological error, and as a result of bugs, misconfigurations or exploited vulnerabilities in software or hardware, could compromise the confidentiality, availability and integrity of Confidential Information and our IT systems. Our efforts to prevent, detect and respond to data

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security incidents, may not be effective due to attackers increasingly using tools and techniques that are designed to circumvent controls, to avoid detection, and to remove or obfuscate forensic evidence. Further, the security measures and procedures our customers, vendors and other users of our systems have in place to protect IT Systems and Confidential Information may not be successful or sufficient to counter all data breaches, cyberattacks or system failures. There can be no assurance that our cybersecurity risk management program and processes, including our policies, controls, or procedures, will be fully implemented, complied with or effective in protecting our IT Systems and Confidential Information.

Our IT Systems may be vulnerable to cyberattacks or security breaches, and third parties may be able to access our, our customers’ or our employees’ Confidential Information, including personal or proprietary information, that is stored on or accessible through those systems. We have experienced and expect to continue to experience in the future, cyberattacks as well as breaches of our security measures due to human error, malfeasance, system errors or vulnerabilities or other irregularities. In the past, one of our vendors providing IT infrastructure management software was compromised by cyberattacks. We are regularly exposed to vulnerabilities in widely deployed third-party software that we use in the ordinary course of business, such as the Log4J vulnerability. While these vulnerabilities did not have a material adverse effect on our operations, they and similar incidents require us to devote time and resources to monitoring and remediation on a regular basis.

In the past three years, we have not experienced a material cybersecurity incident, but any actual or perceived cybersecurity incidents or breaches of our security could result in any or all of the following, among other things, any of which could adversely affect our business and results of operations:

•Interrupt our operations;

•Result in our systems or services being unavailable;

•Result in improper disclosures of data;

•Result in improper payments;

•Materially harm our reputation and brands;

•Result in significant regulatory scrutiny, enforcement actions, legal proceedings and claims (including class action lawsuits) and other legal and financial exposure;

•Cause us to incur significant remediation, system restoration, incident response and compliance costs;

•Lead to loss of customer confidence in, or decreased use of, our products and services;

•Divert the attention of management from the operation of our business; and

•Result in significant contractual penalties or other payments as a result of third-party losses or claims.

In addition, any cyberattacks or data security breaches affecting companies that we acquire our customers or vendors (including data center and cloud computing providers) could have similar negative effects on our business. Further, we may not be able to recover any or all damages suffered as a result of such security breach or other security incident from such third-party providers. Notwithstanding our efforts, there can be no assurance that vulnerabilities in widely deployed software will not materially harm our business. Any breach of our security measures or the loss, inadvertent disclosure or unapproved dissemination of Confidential Information about us or our customers, including the potential loss or disclosure of such information or data, could result in litigation, regulatory enforcement and potential liability for us, damage our brand and reputation or otherwise materially harm our business, financial condition or competitive position.

The coverage under our insurance policies for cybersecurity and related issues may not be adequate to reimburse us for losses caused by cyberattacks or other security incidents or be available on economically reasonable terms or at all.

Technical problems or disruptions that affect either our customers’ ability to access our services, or the software, internal applications, database and network systems underlying our services, could damage our reputation and lead to reduced demand for our information, analytics and online marketplace services, lower revenues and increased costs. Our business, brands and reputation depend upon the satisfactory performance, reliability and availability of our websites, the internet and our service providers. Interruptions in these systems, whether due to system failures, computer viruses, software errors, physical or electronic break-ins, or malicious hacks or attacks on our systems (such as denial of service attacks or use of malware such as ransomware) could affect the security and availability of our services on our mobile applications and our websites and prevent or inhibit users’ access to our services. Our operations also depend on our ability to protect our databases, computers and software, telecommunications equipment and facilities against damage from potential dangers such as fire, flood, power loss, security breaches, computer viruses, telecommunications failures, terrorist attacks, acts of war, electronic and physical break-ins, computer viruses, earthquakes and similar events.

In addition, the software, internal applications and systems underlying our services are complex and may not be error-free. We may encounter technical problems when we attempt to enhance our software, internal applications and systems. Our users rely on our services to conduct their own businesses. Disruptions in, technical problems with, or reductions in ability to access our services for any reason could damage our users’ businesses, harm our reputation, result in additional costs or reduce

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demand for our information, analytics and online marketplace services, any of which could harm our business, results of operations and financial condition.

Amazon Web Services ("AWS") and Akamai Connected Cloud ("ACC") are distributed computing infrastructure platforms for business operations, commonly referred to as “cloud” computing services. We currently run a majority of our computing on AWS and ACC and have built our software and computer systems to use computing, storage capabilities, bandwidth, and other services provided by AWS and ACC. Given this, any significant disruption of or interference with AWS or ACC, whether temporary, regular, or prolonged, would negatively impact our operations and our business.

We also maintain communications, network and computer hardware used to operate some of our mobile applications and websites at facilities in Virginia and California. We do not own or control the operation of certain of these facilities. Our systems and operations are vulnerable to damage or interruption from fire, flood, power loss, security breaches, computer viruses, telecommunications failure, terrorist attacks, acts of war, electronic and physical break-ins, earthquakes and similar events. These risks may be increased with respect to operations housed at facilities we do not own or control. The occurrence of any of the foregoing events could result in damage to our systems and hardware or could cause them to fail completely, and our insurance may not cover such events or may be insufficient to compensate us for losses that may occur.

A failure of our systems at any site could result in reduced functionality for our users, and a total failure of our systems could cause our mobile applications or websites to be inaccessible. Problems faced or caused by our information technology service providers, including content distribution network providers, private network providers, internet service providers and third-party web-hosting providers, or with the systems by which they allocate capacity among their customers (as applicable), could adversely affect the experience of our users. Any financial difficulties, such as bankruptcy reorganization, faced by these third-party service providers or any of the service providers with whom they contract may have negative effects on our business, the nature and extent of which are difficult to predict. If our third-party service providers are unable to keep up with our growing needs for capacity, our business could be harmed. In addition, if distribution channels for our mobile applications experience disruptions, such disruptions could adversely affect the ability of users and potential users to access or update our mobile applications, which could harm our business.

Our business interruption insurance may not cover certain events or may be insufficient to compensate us for the potentially significant losses, including the potential harm to the future growth of our business, which may result from interruptions in our service as a result of system failures or malicious attacks. Any errors, defects, disruptions or other performance problems with our services could harm our reputation, business, results of operations and financial condition.

The significant costs associated with undertaking a large infrastructure project to build out our campus in Richmond, Virginia, have impacted and will continue to impact our financial condition and results of operations. In December 2021, we announced our plans to expand our research and technology center in Richmond, Virginia. These plans have required and will continue to require significant capital expenditures over the next several years and our business plans may change. Future changes in growth or fluctuations in cash flow may also negatively impact our ability to finance this project. Additionally, actual capital expenditures could vary materially from our projected capital expenditures, which could negatively impact our business, operating results and financial condition. If we are provided with any grants, tax credits, abatements or other incentives related to this expansion effort and do not meet requirements associated with those incentives, we may not be able to benefit from those incentives, which could cause the cost of the project to be significantly more than anticipated or significantly increase our taxes above what we currently expect. To date, we have financed construction with cash on hand and plan to finance the remainder of construction in the same way. Use of cash on hand to finance construction has and will continue to reduce the amount of cash available for other corporate uses and could also reduce our ability to meet our scheduled debt service obligations or to meet the covenants required to borrow additional funds under our 2020 Credit Agreement. Any of the foregoing may adversely affect our financial position and results of operations.

Our current or future geographic expansion plans may not result in increased revenues, which may negatively impact our business, results of operations and financial position. Expanding into new markets and increasing the depth of our coverage in existing markets imposes additional burdens on our research, systems development, sales, marketing and general managerial resources. If we are unable to manage our expansion efforts effectively, if our expansion efforts take longer or are more expensive than planned or we are not successful in marketing and selling our services in existing or new markets, our expansion may have a material adverse effect on our financial position by increasing our expenses without increasing our revenues.

Our business and results of operations may be, and our financial condition may be, impacted by the lasting effects of the COVID-19 pandemic on the global economy, the real estate industry, and our customers and such impact could be materially adverse and continue for an unknown period of time. The COVID-19 pandemic created significant economic volatility, uncertainty and disruption around the world, including in the real estate industry.

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The demand for office space decreased during and following the COVID-19 pandemic as businesses implemented hybrid or all work-from-home arrangements in response to employee desire for more flexibility, which may lead to a downturn in the commercial real estate market. A depressed commercial real estate market would have a negative impact on our core customer base, which could impact our customers’ ability to subscribe and pay for our services and reduce demand for our services. Reduced demand and increased cancellations could cause our revenues or our revenue growth rates to decline and reduce our profitability. The extent and duration of any future weakening of the economy or future downturns in the commercial real estate market as a lasting result of the COVID-19 pandemic is unknown, and there can be no assurance that any of the governmental or private sector initiatives designed to strengthen the economy will be successful or available to us and our customers and, if successful, when the benefits will be seen.

We are subject to a number of risks related to acceptance of credit cards and debit cards and facilitation of other customer payments.

We depend on processing vendors to process a significant number of credit and debit card transactions and ACH payments, for payments made to us directly for our services, by renters to landlords using our online leasing services, or by real estate agents to purchase our Homes.com services. If we or any one or more of these service providers fail to maintain adequate systems to authorize and process credit card transactions, one or more of the major credit card companies could disallow our continued use of their payment products. If we are unable to maintain our chargeback rate or refund rates at acceptable levels, our processing vendors may increase our transaction fees or terminate their relationships with us. We could lose customers if we are not able to continue to use payment products of the major credit card companies. Further, if we or any one or more of these service providers fail to maintain adequate systems for authorization and processing of credit, debit, ACH or similar payments or if any such service provider were to terminate or modify its relationship with us unexpectedly, our ability to process those customer transactions would be adversely affected, which could decrease sales, discourage customers away from our marketplace services, result in potential legal liability, and harm our business and reputation. In addition, if the systems for the authorization and processing of credit card transactions fail to work properly and, as a result, we do not charge our customers’ credit cards on a timely basis or at all, our business, revenue, results of operations and financial condition could be harmed.

We are also subject to payment card association operating rules, certification requirements and rules governing electronic funds transfers, which could change or be reinterpreted in ways that make it more difficult for us to comply. We are required to comply with payment card industry security standards. Failing to comply with those standards may violate payment card association operating rules, federal and state laws and regulations and the terms of our contracts with payment processors. Any failure to comply also may subject us to fines, penalties, damages and civil liability, and may result in the loss of our ability to accept credit and debit card payments. Further, there is no guarantee that such compliance will prevent illegal or improper use of our payment systems or the theft, loss, or misuse of data pertaining to credit and debit cards, cardholders and transactions.

The payment methods that we offer also subject us to potential fraud and theft by criminals, who are becoming increasingly sophisticated, seeking to obtain unauthorized access to or exploit weaknesses that may exist in the payment systems. If we fail to comply with applicable rules or requirements for the payment methods we accept, or if payment-related data are compromised due to a breach of data, we may be liable for significant costs incurred by payment card issuing banks and other third parties or subject to fines and higher transaction fees, or our ability to accept or facilitate certain types of payments may be impaired. In addition, our customers could lose confidence in certain payment types, which may result in a shift to other payment types or potential changes to our payment systems that may result in higher costs. If we fail to adequately control fraudulent payment transactions, we may face civil liability, diminished public perception of our security measures and higher costs, each of which could harm our business, results of operations and financial condition.

If we are unable to maintain our chargeback rate or refund rates at acceptable levels, our processing vendors may increase our transaction fees or terminate their relationships with us. Any increases in our credit and debit card fees could harm our results of operations, particularly if we elect not to raise our rates for our services to offset the increase. The termination of our ability to process payments on any major credit or debit card would significantly impair our ability to operate our business.

Climate change and other events beyond our control could harm our business. Natural disasters, disease outbreaks and pandemics, power shortages, terrorism, political unrest, telecommunications failure, vandalism, geopolitical instability, war, climate change, and other events beyond our control could negatively impact our operations or otherwise harm our business. Such events may result in damage or loss of service to our data centers or other infrastructure that our operations rely on, potentially reduce the attractiveness of real estate in areas we provide services, cause delays in product development or availability, or result in losses of critical data, any of which may adversely impact our operations.

In addition, the impacts of climate change on the global economy and our industry are rapidly evolving. Physical impacts of climate change (including, but not limited to, floods, droughts, more frequent and/or intense storms, and wildfires) may

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disrupt our operations, as well as the operations of our suppliers and customers. Longer-term physical impacts may also result in changing consumer preferences, which may adversely impact demand for certain of our products. Transition impacts of climate change may subject us to increased regulations, reporting requirements (such as the SEC’s proposed climate change disclosure rule), standards, or expectations regarding the environmental impacts of our business. Failure to disclose accurate information in a timely manner may also adversely affect our reputation, business, or financial performance.

Increased attention to ESG matters may require us to incur additional costs or otherwise adversely impact our business. Increased attention to climate change; diversity, equity, and inclusion; and other ESG issues, as well as societal expectations regarding voluntary ESG initiatives and disclosures, may result in increased costs (including, but not limited to, increased costs related to compliance, stakeholder engagement, and contracting), impact our reputation, or otherwise affect our business performance. In addition, organizations that provide information to investors on corporate governance and related matters have developed ratings processes for evaluating companies on ESG matters. Such ratings are used by some investors to inform their investment or voting decisions. Unfavorable ESG ratings could lead to negative investor sentiment toward us and/or our industry, which could have a negative impact on our access to and costs of capital. To the extent ESG matters negatively impact our reputation, we may also not be able to compete as effectively to recruit or retain employees. We may take certain actions, including the establishment of ESG-related goals or targets, to improve the ESG profile of our Company and/or offerings and/or to respond to stakeholder demand; however, such actions may be costly or be subject to numerous conditions that are outside our control, and we cannot guarantee that such actions will have the desired effect.

Moreover, while we may create and publish voluntary disclosures regarding ESG matters from time to time, many of the statements in those voluntary disclosures are based on hypothetical expectations and assumptions that may or may not be representative of current or actual risks or events or forecasts of expected risks or events, including the costs associated therewith. Such expectations and assumptions are necessarily uncertain and may be prone to error or subject to misinterpretation given the long timelines involved and the lack of an established single approach to identifying, measuring and reporting on many ESG matters. Such disclosures may also be at least partially reliant on third-party information that we have not independently verified or cannot be independently verified. In addition, we expect there will likely be increasing levels of regulation, disclosure-related and otherwise, with respect to ESG matters, and increased regulation will likely lead to increased compliance costs as well as scrutiny that could heighten all of the risks identified in this risk factor. Such ESG matters may also impact our suppliers or customers, which may adversely impact our business, financial condition, or results of operations.

Risks related to our data, intellectual property and listings

If we are not able to obtain and maintain accurate, comprehensive or reliable data, we could experience reduced demand for our information, analytics and online marketplace services. Our success depends on our clients’ confidence in the comprehensiveness, accuracy and reliability of the data and analysis we provide.

Establishing and maintaining accurate and reliable data and analysis is challenging. If our data, including the data we obtain from third parties or directly from brokers through the Marketing Center feature on CoStar and LoopNet, or analysis is not current, accurate, comprehensive or reliable, we could experience reduced demand for our services or be subject to legal claims by our customers, either of which could result in lower revenues and higher expenses.

If we are unable to enforce or defend our ownership and use of intellectual property, our business, brands, competitive position and operating results could be harmed. The success of our business depends in large part on our intellectual property, including intellectual property involved in our methodologies, databases, services and software. We rely on a combination of trademark, trade secret, patent, copyright and other laws, nondisclosure and noncompetition provisions, license agreements and other contractual provisions and technical measures to protect our intellectual property rights. However, current law may not provide for adequate protection of our databases and the actual data. In addition, legal standards relating to the validity, enforceability and scope of protection of proprietary rights in internet-related businesses are uncertain and evolving, and changes in these standards may adversely impact the viability or value of our proprietary rights. We find our proprietary content on competitors’ sites. If we are not successful in protecting our intellectual property, including our content, our brands and our business, results of operations and financial condition could be harmed. The same would be true if a court found that our services infringe other persons’ intellectual property rights. Any intellectual property lawsuits or threatened lawsuits in which we are involved, either as a plaintiff or as a defendant, have cost us and could continue to cost us a significant amount of time and money and distract management’s attention from operating our business. In addition, if we do not prevail on an intellectual property claim, this could result in a change to our methodology or information, analytics and online marketplace services and could reduce our profitability.

Effective trademark, trade secret, patent and copyright protection may not be available in every country in which we provide our services. The laws of certain countries do not protect proprietary rights to the same extent as the laws of the U.S. and, therefore, in certain jurisdictions, we may be unable to protect our intellectual property and our proprietary technology

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adequately against unauthorized third-party copying or use, which could harm our competitive position. This risk will increase as we continue to expand our business into new international jurisdictions.

We may not be able to successfully halt the operation of websites that aggregate our data, as well as data from other companies, or "copycat" websites that may misappropriate our data. We have expended significant resources to develop proprietary content and any misappropriation of our data could reduce that value of that content or our return on investment related to that content, which could harm our competitive position and results of operations. Third parties may misappropriate our data through website scraping, robots or other means and aggregate and display this data on their websites. Artificial intelligence is becoming increasingly powerful and sophisticated, and third parties may utilize artificial intelligence to misappropriate our data more quickly and at a larger scale than in the past. In addition, “copycat” websites may misappropriate data on our website and attempt to imitate our brands or the functionality of our website. We may not be able to detect all such websites in a timely manner and, even if we could, technological and legal measures available to us may be insufficient to stop their operations and the misappropriation of our data. Any measures that we may take to enforce our rights could require us to expend significant financial or other resources.

We may be subject to legal liability for collecting, displaying or distributing information. Because the content in our database is collected from various sources and distributed to others, we may be subject to claims for breach of contract, defamation, negligence, unfair competition or copyright or trademark infringement or claims based on other theories, such as breach of laws related to privacy and data protection. We could also be subject to claims based upon the content that is accessible from our website through links to other websites or information on our website supplied by third parties. Even if these claims do not result in liability to us, we could incur significant costs in investigating and defending against any claims, and we could be subject to public notice requirements that may affect our reputation. Our potential liability for information distributed by us to others could require us to implement measures to reduce our exposure to such liability, which may require us to expend substantial resources and limit the attractiveness of our information, analytics and online marketplaces to users. These risks may be exacerbated from impacts, or perceived impacts, of emerging technologies (including, but not limited to, machine learning) on human rights, privacy, or other social considerations, which may result in reputational harm, compliance costs for any new rules or interpretations, or other adverse impacts on our operations and financial performance.

If we are unable to obtain or retain listings from real estate brokers, agents, property owners and apartment property managers, our marketplace services could be less attractive to current or potential customers, which could reduce our revenues. The value of our real estate marketplace services to our customers depends on our ability to increase the number of property listings provided and searches conducted. As the number of listings increases, so does the utility of a marketplace’s search, listing and marketing services. We depend substantially on brokers, agents, property owners and, in the case of apartment rentals, property managers to submit listings to our marketplaces. If these parties choose not to continue their listings with us, or choose to list them with a competitor, our marketplace services could be less attractive to other real estate industry transaction participants, resulting in reduced revenue.

We may not be able to maintain or establish relationships with third-party listing providers, which could limit the information we have to power our products and services and impair our ability to attract or retain customers. Our ability to attract agents and consumers to our Homes.com Network, its websites and mobile applications and other residential real estate tools depends, to some degree, on us providing timely access to comprehensive and accurate real estate listings and information. We get listings data primarily from MLSs in the markets we serve. We also source listings data from public records, other third-party listing providers, and other sources. Many of our agreements with real estate listing providers may be terminated with limited notice or cause. Many of our competitors and other real estate websites have similar access to MLSs and listing data and may be able to source certain real estate information faster or more efficiently than we can. Because MLS participation is voluntary, brokers and homeowners may decline to post their listings data to their local MLS or may seek to change or limit the way that data is distributed. Another industry participant or group could create a new listings data service, which could impact the relative quality or quantity of information of our listing providers. The loss of existing relationships with MLSs and other listing providers, whether due to termination of agreements, loss of MLS memberships, or otherwise, changes to our rights to use or timely access listing data or an inability to continue to add new listing providers or changes to the way real estate information is shared, may negatively impact our listing data quality. This could markedly decrease the quantity and quality of the sale and rental data we provide, reduce customer confidence in our products and services and cause customers to go elsewhere for real estate listings and information, which could severely harm our business, results of operations and financial condition.

If we fail to comply with the rules and compliance requirements of MLSs, our access to and use of listings data may be restricted or terminated. Our products and services access and use listings data through MLS memberships and must comply with each MLS’s rules and compliance requirements to maintain their access to listings data and remain a member in good standing. Each MLS has adopted its own rules, policies, and agreement terms governing, among other things, how MLS data

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may be used and how listings data must be displayed on our websites and mobile applications. MLS members are also subject to compliance operations requirements and, as a result, must respond to complaints lodged by the MLS or other MLS participants on required timelines. MLS rules vary among markets and are in some cases inconsistent between MLSs, such that we are required to customize our websites, mobile applications, or services to accommodate differences between MLS rules. Handling complaints received by MLS members across markets may create heightened operational or financial risks with short response and resolution deadlines. Complying with the rules and compliance requirements of each MLS requires significant investment, including personnel, technology and development resources, and the exercise of considerable judgment. Rules and compliance requirements of MLSs may be changed across markets, including potential for targeted changes in response to our operations. If we are deemed to be noncompliant with an MLS’s rules or to have provided improper responses to or resolution of complaints, we may face disciplinary sanctions by that MLS, which could include monetary fines, restricting or terminating our access to that MLS’s data, or other disciplinary measures. The loss or degradation of this listings data could materially and adversely affect traffic to our websites and mobile applications, which could severely harm our business, results of operations and financial condition.

Risks related to our international operations

International operations expose us to additional business risks, which may reduce our profitability. Our international operations and expansion subject us to additional business risks, including: currency exchange rate fluctuations; difficulty in adapting to the differing business practices and laws in foreign countries, including differing laws regarding privacy and data protection; difficulty in managing foreign operations; limited protection for intellectual property rights in some countries; difficulty in collecting accounts receivable and longer collection periods; costs of enforcing contractual obligations; impact of recessions in economies outside the U.S.; geopolitical instability, terrorism and war; and potentially adverse tax consequences. In addition, international expansion imposes additional burdens on our executive and administrative personnel, systems development, research and sales departments and general managerial resources. If we are not able to manage our international operations successfully, we may incur higher expenses and our profitability may be reduced. Finally, the investment required for additional international expansion sometimes exceeds the profit generated from such expansion, which reduces our profitability and may adversely affect our financial position.

Fluctuating foreign currency exchange rates may negatively impact our business, results of operations and financial position. A portion of our business is denominated in foreign currencies. We translate sales and other results denominated in foreign currency into U.S. dollars for our financial statements. During periods of a strengthening U.S. dollar, our reported international sales and earnings could be reduced because foreign currencies may translate into fewer U.S. dollars. Foreign currency exchange rates have fluctuated and may continue to fluctuate.

Significant foreign currency exchange rate fluctuations may negatively impact our international revenue, which in turn affects our consolidated revenue. Currently, we are not party to any hedging transactions intended to reduce our exposure to exchange rate fluctuations. We may seek to enter into hedging transactions in the future, but we may be unable to enter into these transactions successfully, on acceptable terms or at all. We cannot predict whether we will incur foreign exchange losses in the future. Further, significant foreign exchange rate fluctuations resulting in a decline in the respective local currency may decrease the value of our foreign assets, as well as decrease our revenues and earnings from our foreign subsidiaries, which would reduce our profitability and adversely affect our financial position.

Risks related to our indebtedness

We have a significant amount of indebtedness, which could decrease our flexibility and adversely affect our business, financial condition and results of operations. As of December 31, 2023, we had $1 billion of Senior Notes outstanding and an additional approximately $750 million available to be drawn under the 2020 Credit Agreement. Borrowings under the 2020 Credit Agreement bear interest at varying rates and expose us to interest rate risk. There can be no assurance that our future cash flows will be sufficient to make payments of interest or principal on the Senior Notes or any amounts due and payable under the 2020 Credit Agreement. If our cash flows and capital resources are insufficient to fund our debt service obligations, we could face substantial liquidity problems and could be forced to reduce or delay investments and capital expenditures or to dispose of material assets or operations, seek additional debt or equity capital or restructure or refinance our indebtedness. We may not be able to effect any such alternative measures on commercially reasonable terms or at all, and, even if successful, those alternative actions may not allow us to meet our scheduled debt service obligations. Furthermore, we may incur substantial additional indebtedness, including secured indebtedness, and if we incur additional indebtedness or other liabilities, the related risks that we face could intensify.

The 2020 Credit Agreement contains customary restrictive covenants imposing operating and financial restrictions on us, including restrictions that may limit our ability to engage in acts that we believe may be in our long-term best interests. These covenants restrict our ability and the ability of our domestic subsidiaries to, among other things, (i) incur additional indebtedness, (ii) incur liens, (iii) pay dividends or make certain other restricted payments, investments or acquisitions, (iv)

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merge or consolidate with another person, and (v) sell, assign, lease or otherwise dispose of all or substantially all of our assets. In addition, the 2020 Credit Agreement requires us to comply with a maintenance covenant that we will not exceed a total net leverage ratio, calculated as total consolidated debt, net of up to $1.0 billion of unrestricted cash and cash equivalents, to consolidated EBITDA, of 4.50 to 1.00. The operating restrictions and financial covenants in the 2020 Credit Agreement may limit our ability to finance future operations or capital needs, to engage in other business activities or to respond to changes in market conditions. Our ability to comply with any financial covenants could be affected materially by events beyond our control, and we may be unable to satisfy any such requirements. If we fail to comply with these covenants, we may need to seek waivers or amendments of such covenants, seek alternative or additional sources of financing or reduce our expenditures. We may be unable to obtain such waivers, amendments or alternative or additional financing on a timely basis or at all, or on favorable terms.

A breach of the covenants under the 2020 Credit Agreement or the indenture that governs the Senior Notes could result in an event of default under the applicable indebtedness. Such a default may allow the creditors to accelerate the related debt and may result in the acceleration of any other debt to which a cross-acceleration provision applies. In the event the holders of the Senior Notes or our other debt accelerate the repayment of our borrowings, we and our subsidiaries may not have sufficient assets to repay that indebtedness.

In May 2023, we amended the 2020 Credit Agreement to replace LIBOR as the reference rate with Term SOFR for U.S. dollar-denominated borrowings, SONIA rates for Sterling-denominated borrowings and EURIBOR for Euro-denominated borrowings. It is unclear, however, whether SOFR, SONIA or EURIBOR will retain market acceptance as a LIBOR replacement tool, and we may need to renegotiate our 2020 Credit Agreement if other LIBOR alternatives are established and become more widely adopted. Each of SOFR, SONIA and EURIBOR differ from LIBOR, both in the actual rate and how it is calculated. It is not possible to predict what effect the change to SOFR, SONIA and EURIBOR may have on our interest rates.

Our indebtedness increases our vulnerability to general adverse economic and industry conditions; requires us to dedicate a portion of our cash flow from operations to payments on indebtedness, reducing the availability of cash flow to fund capital expenditures, marketing and other general corporate activities; limits our ability to borrow additional funds; and may limit our flexibility in planning for, or reacting to, changes in our business and the industries in which we operate.

A lowering or withdrawal of the ratings assigned to our debt securities by rating agencies may increase our future borrowing costs, reduce our access to capital or result in the loss of certain covenant suspensions. Our debt rating could be lowered or withdrawn entirely by a rating agency if, in that rating agency’s judgment, future circumstances relating to the basis of the rating, such as adverse changes, warrant. Any future lowering of our ratings likely would make it more difficult or more expensive for us to obtain additional debt financing.

In addition, during a Covenant Suspension Period, certain customary negative and affirmative covenants contained in the 2020 Credit Agreement are suspended, including the covenants restricting affiliate transactions, incurrence of indebtedness, investments, asset sales and restricted payments. A lowering of one or both of our investment grade ratings would result in increased compliance costs and would impose certain operating restrictions, either of which could be materially adverse to our operations and financial results.

Risks related to regulatory compliance and legal matters

Our actual or perceived failure to comply with privacy laws and standards could adversely affect our business, financial condition and results of operations. We depend on IT Systems. We own and manage some IT Systems but also rely on third-party service providers and vendors for a range of products and services, including cloud products/services, that are critical to internal and/or external customer-facing operations. In the course of our business, we and certain of our third-party providers collect, use, transmit and disclose Confidential Information, including personal data about our employees, current and potential customers and employees of third parties we work with.

As a result, we are subject to a variety of state, national and international laws and regulations that apply to the collection, use, retention, protection, disclosure, transfer and other processing of personal information, including, but not limited to, the GDPR and CCPA. These laws and regulations are evolving, with new or modified laws and regulations proposed and implemented frequently and existing laws and regulations subject to new or different interpretations. For example, the GDPR creates data protection requirements in the EU and UK and imposes substantial fines for breaches of the data protection rules. The GDPR increased our responsibility and liability in relation to personal data that we process. The CCPA, among other things, provides the rights to California residents related to their personal information, places limitations on data uses and creates new audit requirements for higher risk data. The CCPA also provides for civil penalties for violations, as well as a private right of action for data breaches that may increase data breach litigation. Other state privacy laws apply to operations, and similar laws have been proposed, and likely will continue to be proposed, in other states and at the federal level, and if passed, may have potentially conflicting requirements that would make compliance challenging.

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In addition to risks we face under applicable privacy laws, we are subject to evolving consumer protection and marketing laws and increased litigation and government enforcement by the Federal Trade Commission and state Attorneys General. These agencies are aggressively interpreting and enforcing federal and state consumer protection laws in relation to very broad sales and marketing and advertising contexts. There are also federal laws covering our activities that are a source of potential liability for our business, including the CAN-SPAM Act, the TCPA, and the FCRA. In particular, any claims that we have violated the TCPA could be costly to litigate and could expose us to substantial statutory damages or settlement costs.

Any failure or alleged failure to comply with privacy, data protection or consumer protection laws could lead to government enforcement actions and litigation and significant penalties against us, and could materially adversely affect our reputation, business, financial condition, cash flows and results of operations. Compliance with any of the foregoing laws and regulations can be costly, can delay or impede the development of new products, and may require us to change the way we operate.

The interpretation and application of many privacy and data protection laws are uncertain. These laws may be interpreted and applied in a manner that is inconsistent with our existing data management practices or the features of our products. If so, in addition to the possibility of negative publicity, fines, lawsuits and other claims and penalties, we could be required to fundamentally change our business activities and practices or modify our products, which could harm our business.

Changes in tax laws, regulations or fiscal and tax policies or the manner of their interpretation or enforcement could adversely impact our financial performance. New tax laws or regulations, or changes in existing laws or regulations, or the manner of their interpretation or enforcement, could increase our cost of doing business. In addition, from time to time, U.S. and foreign tax authorities, including state and local governments, consider legislation that could increase our effective tax rate. Further, the Organization for Economic Co-operation and Development has a framework to implement a global minimum corporate tax of 15% for companies with global revenues and profits above certain thresholds (referred to as Pillar 2), with certain aspects of Pillar 2 effective January 1, 2024 and other aspects effective January 1, 2025. While it is uncertain whether the U.S. will enact legislation to adopt Pillar 2, certain countries in which we operate have adopted legislation, and other countries are in the process of introducing legislation to implement Pillar 2. Although we do not expect Pillar 2 to have a material impact on our effective tax rate or our consolidated results of operations, financial position, and cash flows at this time, certain implementation details have yet to be developed, and the enactment of certain of these changes has not yet taken effect in all jurisdictions in which we operate. As a result, these changes may have adverse consequences for us, may increase our compliance costs and may increase the amount of tax we are required to pay in certain jurisdictions.

Third-party claims, litigation, regulatory proceedings or government investigations to which we are subject or in which we become involved, regardless of their merit, may significantly increase our expenses and adversely affect our stock price. From time to time we may be subject to third-party claims, lawsuits, regulatory proceedings or government investigations into whether our business practices comport with applicable law, which may include claims with respect to intellectual property, cybersecurity, privacy, data protection, antitrust, breach of contract, employment, mergers and acquisitions and other matters. Regardless of the merit of such claims, proceedings or investigations, defending against them could cost us a significant amount of time and money, result in negative publicity, and/or adversely affect our stock price. In addition, if any claims or proceedings are decided against us or if a settlement requires us to pay a large monetary amount or take other action that materially restricts or impedes our operations, our profitability could be significantly reduced and our financial position could be adversely affected.

We do not currently intend to pay dividends on our common stock and, consequently, your ability to achieve a return on your investment will depend on appreciation in the price of our common stock. We have never declared or paid any cash dividends on our common stock and do not intend to do so for the foreseeable future. We currently intend to invest our future earnings, if any, to finance our growth or share repurchases. In addition, provisions of the 2020 Credit Agreement governing our credit facilities limit our ability to pay cash dividends. Therefore, you are not likely to receive any dividends on your common stock for the foreseeable future and the success of an investment in shares of our common stock will depend upon any future appreciation in their value. There is no guarantee that shares of our common stock will appreciate in value or even maintain the price at which our stockholders have purchased their shares.

Item 1B.    Unresolved Staff Comments

None.

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Item 1C.    Cybersecurity

Cybersecurity Risk Management and Strategy

We have developed and implemented a cybersecurity risk management program intended to protect the confidentiality, integrity, and availability of our critical systems and information.

Our cybersecurity risk management program is guided by the National Institute of Standards and Technology Cybersecurity Framework (NIST CSF). This does not imply that we meet any particular technical standards, specifications, or requirements at all times, only that we use the NIST CSF as a guide to help us identify, assess, and manage cybersecurity risks relevant to our business. Additionally, we engage a third-party vendor regularly to benchmark our information security program’s maturity against the NIST CSF.

Our cybersecurity risk management program is integrated into our overall enterprise risk management program, and shares common methodologies, reporting channels and governance processes that apply across the enterprise risk management program to other legal, compliance, strategic, operational, and financial risk areas.

Key elements of our cybersecurity risk management program include, but are not limited to the following:

a.Internal and external asset identification, assessment, monitoring and classification procedures to evaluate cybersecurity risks and inform mitigation efforts.

b.A security team principally responsible for managing (1) our cybersecurity risk assessment processes, (2) our cyber processes, and (3) our cyber threat and incident response;

c.The use of external service providers, where appropriate, to assess defenses, analyze threat intelligence, or otherwise assist with aspects of our security controls;

d.Cybersecurity awareness training of our employees, software development teams, incident response personnel, and senior management;

e.A cybersecurity incident response plan that includes procedures for responding to cybersecurity incidents; and regular tabletop exercises to assess our response readiness; and

f.A third-party risk management process for key service providers, suppliers, and vendors who access critical systems and data based on risk profile.

We have not identified material risks from known cybersecurity threats, including as a result of any prior cybersecurity incidents, that have materially affected us, including our operations, business strategy, results of operations, or financial condition. We face certain ongoing risks from cybersecurity threats that, if realized, are reasonably likely to materially affect us, including our operations, business strategy, results of operations, or financial condition. See Risk Factors – “Cyberattacks and security vulnerabilities could result in serious harm to our reputation, business and financial condition.” and “Technical problems or disruptions that affect either our customers’ ability to access our services, or the software, internal applications, database and network systems underlying our services, could damage our reputation and lead to reduced demand for our information, analytics and online marketplace services, lower revenues and increased costs.”

Cybersecurity Governance

Our Board considers cybersecurity risk as part of its risk oversight function and has delegated to the Audit Committee oversight of cybersecurity and other information technology risks. The Audit Committee oversees management’s implementation of our cybersecurity risk management program.

Our Audit Committee receives reports from management on our cybersecurity risks. In addition, management updates the Audit Committee, as necessary, regarding any significant cybersecurity incidents. The Audit Committee reports to the full Board regarding its activities, including those related to cybersecurity.

Our management team is informed and monitors the prevention, detection, mitigation and remediation of cybersecurity threats. The team has primary responsibility for our overall cybersecurity risk management program and supervises both our internal cybersecurity personnel and our retained external cybersecurity consultants. Our management team’s experience includes industry-recognized certifications, such as CISSP, CISM, and CISA, decades of experience as part of our IT team, and previous cybersecurity leadership positions at various Fortune 500 companies and U.S. Defense contractors.

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Our management team is informed about and monitors the prevention, detection, mitigation, and remediation of cybersecurity risks and incidents through various means, which may include briefings from internal security personnel; threat intelligence and other information obtained from governmental, public or private sources, including external consultants engaged by us; and alerts and reports produced by security tools deployed in the IT environment.

Item 2.    Properties

Our headquarters is located at 1331 L Street, NW, in downtown Washington, DC, where we occupy approximately 169,000 square feet of office space, with a lease that expires on May 31, 2025 (with two five-year renewal options). Our headquarters is used primarily by our North America operating segment. Our principal facility in the U.K. is located in London, where we occupy 42,000 square feet of office space. Our lease for this facility has a term ending August 31, 2025. This facility is used by our International operating segment, including our recent acquisition, OnTheMarket.

Our staff in Richmond, Virginia occupy an owned building located at 501 S 5th Street, where we occupy approximately 310,000 square feet, an owned building located at 901 Semmes Avenue, where we own and occupy approximately 117,000 square feet; and leased space at 951 E Byrd St., where we occupy approximately 97,000 square feet. These locations house research, product development and sales functions. All of our owned properties are held under fee simple ownership and are not materially encumbered.

We also operate certain of our research, development and sales functions out of additional leased office spaces in Irvine, California; San Diego, California; and Atlanta, Georgia. Additionally, we lease office space in a variety of other metropolitan areas. These locations include, among others, the following: Hendersonville, Tennessee; Norfolk, Virginia; Boston, Massachusetts; New York, New York; San Francisco, California; and Los Angeles, California. 

We believe these facilities are suitable and appropriately support our business needs.

Item 3.    Legal Proceedings

Currently, and from time to time, we are involved in litigation incidental to the conduct of our business, including, among others, the legal actions discussed under “Contingencies” in Note 13 “Commitments and Contingencies” of the Notes to our Consolidated Financial Statements. While our management presently believes that the ultimate outcome of these proceedings, individually and in the aggregate, will not materially harm our business, financial position, future results of operations or liquidity, legal proceedings are inherently uncertain, and unfavorable rulings could, individually or in the aggregate, have a material adverse effect on our business, financial position, future results of operations or liquidity.

Item 4.    Mine Safety Disclosures

Not Applicable.

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PART II

Item 5.    Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

Our common stock is traded on the Nasdaq Global Select Market under the symbol “CSGP.” As of January 31, 2024, there were 1,654 holders of record of our common stock.

Dividend Policy. We have never declared or paid any dividends on our common stock. We do not anticipate paying any dividends on our common stock during the foreseeable future, but intend to retain any earnings for future growth of our business.

Recent Issues of Unregistered Securities. We did not issue any unregistered securities during the year ended December 31, 2023.

Issuer Purchases of Equity Securities. The following table is a summary of our repurchases of common stock for the quarter ended December 31, 2023:

ISSUER PURCHASES OF EQUITY SECURITIES

2023	Total Number of Shares Purchased(1)	Average Price Paid per Share		Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs	Maximum Number of Shares that May Yet Be Purchased Under the Plans or Programs
October 1 through 31	12,677	$	76.89	—	—
November 1 through 30	14,445	73.48		—	—
December 1 through 31	8,252	88.25		—	—
Total	35,374	$	78.15	—	—
___________________

(1) The number of shares purchased consists of shares of common stock tendered by employees to the Company to satisfy the employees' minimum tax withholding obligations arising as a result of vesting of restricted stock grants under the Company’s 2016 Stock Incentive Plan, as amended, which shares were purchased by the Company based on their fair market value on the trading day immediately preceding the vesting date. None of these share purchases were part of a publicly announced program to purchase common stock of the Company.

Stock Price Performance Graph

The stock performance graph below shows how an initial investment of $100 in our common stock would have compared to:

•An equal investment in the S&P 500 Index; and

•An equal investment in the S&P 500 Internet Services & Infrastructure Index.

The comparison covers the period beginning December 31, 2018 and ending on December 31, 2023, and assumes the reinvestment of any dividends. Note that this performance is historical and is not necessarily indicative of future price performance.

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Company / Index	12/31/18		12/31/19		12/31/20		12/31/21		12/31/22		12/31/23
CoStar Group, Inc.	$	100.00	$	177.36	$	273.99	$	234.27	$	229.09	$	259.06
S&P 500 Index	100.00		131.49		155.68		200.37		164.08		207.21
S&P 500 Internet Services & Infrastructure Index	100.00		134.46		156.09		178.95		137.79		160.76

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Item 6.    Reserved

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Item 7.    Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following Management’s Discussion and Analysis of Financial Condition and Results of Operations contains “forward-looking statements,” including statements about our beliefs and expectations. There are many risks and uncertainties that could cause actual results to differ materially from those discussed in the forward-looking statements. Potential factors that could cause actual results to differ materially from those discussed in any forward-looking statements include, but are not limited to, those stated above in under the heading “Cautionary Statement Concerning Forward-Looking Statements” and in Item 1A. under the heading “Risk Factors,” as well as those described from time to time in our filings with the SEC.

All forward-looking statements are based on information available to us on the date of this filing and we assume no obligation to update such statements, whether as a result of new information, future events or otherwise. The following discussion should be read in conjunction with our Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and other filings with the SEC and the consolidated financial statements and related notes included in this Report.

Overview

Our principal information, analytics and online marketplace services are described in the following paragraphs by type of service:

CoStar

CoStar is our subscription-based integrated platform for commercial real estate intelligence, which includes information about office, industrial, retail, multifamily, hospitality and student housing properties, properties for sale, comparable sales, tenants, space available for lease, industry professionals and their business relationships, industry news and market status and provides lease analytical, risk management, and hospitality benchmarking capabilities. CoStar's revenue growth rate for the year ended December 31, 2023 slowed compared to the year ended December 31, 2022. We expect CoStar's revenue growth rate for the year ending December 31, 2024 to be consistent with the revenue growth rate for the year ended December 31, 2023 primarily due to converting legacy STR customers to our new CoStar based benchmarking product offsetting lower inflation-based price adjustments.

Information Services

We provide real estate and lease management technology solutions, including lease administration, lease accounting and abstraction services, through our CoStar Real Estate Manager service offerings, as well as portfolio and debt analysis, management and reporting capabilities through our CoStar Risk Analytics service offerings. We also provide benchmarking and analytics for the hospitality industry both on a subscription basis and an ad hoc basis. We earn revenue on ad hoc transactions as reports or data are delivered to customers. We provide information services internationally, through our Business Immo, Belbex and Thomas Daily businesses in France, Spain and Germany, respectively. Information Services revenue growth rate for the year ended December 31, 2023 slowed compared to the year ended December 31, 2022. We expect Information Services' revenue growth rate for the year ending December 31, 2024 to slow compared to the revenue growth rate for the year ended December 31, 2023 as a result of transitioning legacy STR customers to our new CoStar based benchmarking product.

Multifamily

Apartments.com is the flagship brand of our apartment marketing network of subscription-based advertising services and provides property management companies and landlords with a comprehensive advertising destination for their available rental units and offers renters a platform for searching for available rentals. This network also earns transaction-based revenue primarily from providing online tenant applications, including background and credit checks, and rental payment processing. Multifamily's revenue growth rate for the year ended December 31, 2023 accelerated compared to the year ended December 31, 2022 as a result of higher sales volumes driven by increases in pricing on renewals and an increase in the number of properties listed on our network. We expect Multifamily's revenue growth rate for the year ending December 31, 2024 to moderate compared to the revenue growth rate for the year ended December 31, 2023 due to lower inflation-based price adjustments.

LoopNet

Our LoopNet network of commercial real estate websites offer subscription-based, online marketplace services that enable commercial property owners, landlords and real estate agents working on their behalf to advertise properties for sale or for lease and to submit detailed information about property listings. Commercial real estate agents, buyers and tenants use the LoopNet network of online marketplace services to search for available property listings that meet their criteria. LoopNet's revenue growth rate for the year ended December 31, 2023 accelerated compared to the year ended December 31, 2022, due to an increase in the average price per listing. We expect LoopNet's revenue growth rate for the year ending December 31, 2024 to

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slow compared to the revenue growth rate for the year ended December 31, 2023 as a result of disruptions related to transitioning sales and service activities to a dedicated LoopNet field sales team.

Residential

Our Homes.com Network and the acquisition of OnTheMarket have enabled us to expand our offerings to the residential for sale market. Homes.com is a homes for sale listings site that combines our proprietary research with listing information to allow homebuyers an informative and collaborative experience finding homes for sale or lease. Homes.com provides residential real estate professionals subscription-based access to applications that manage residential real estate agent workflow and receives transaction-based revenue for marketing campaigns delivered on third-party platforms. In February 2024, we began selling subscription memberships to promote the home listing as well as the agent in the sort order. OnTheMarket is a property portal in the U.K., which primarily offers subscriptions-based advertising services to agents. Residential's revenues for the year ended December 31, 2023 decreased compared to the year ended December 31, 2022, due to the discontinuation of certain non-strategic products and services. We expect Residential's revenues for the year ending December 31, 2024 to increase compared to the year ended December 31, 2023 due to the OnTheMarket Acquisition and the launch of our new Homes.com product.

Other Marketplaces

Our other marketplaces include Ten-X, an online auction platform for commercial real estate and our BizBuySell and Land.com networks. The BizBuySell network provides online marketplaces for businesses and franchises for sale, and THE Land.com network provides online marketplaces for rural land for sale. Other marketplaces' revenues for the year ended December 31, 2023 decreased compared to the year ended December 31, 2022, due to lower Ten-X transaction revenue, partially offset by growth in other products. We expect other marketplaces' revenues for the year ending December 31, 2024 to be consistent with the revenues for the year ended December 31, 2023.

Subscription-based Services

The majority of our revenue is generated from service offerings that are distributed to our clients under subscription-based agreements that typically renew automatically and have a term of at least one year. We recognize subscription revenues on a straight-line basis over the life of the contract.

For the years ended December 31, 2023, 2022 and 2021, our annualized net new bookings of subscription-based services on all contracts were approximately $286 million, $305 million and $217 million, respectively. Net new bookings is calculated based on the annualized amount of change in the Company's sales bookings resulting from new subscription-based contracts, changes to existing subscription-based contracts and cancellations of subscription-based contracts for the period reported. Net new bookings is calculated on all subscription-based contracts without regard to contract term. Net new bookings is considered an operating metric that is an indicator of future subscription revenue growth and is also used as a metric of sales force productivity by us and investors. However, information regarding net new bookings is not comparable to, nor should it be substituted for, an analysis of our revenues over time. Revenue from our subscription-based contracts were approximately 95%, 93% and 93% of total revenue for the years ended December 31, 2023, 2022 and 2021, respectively. The increase in the percentage of our revenue from subscription-based contracts from 2022 to 2023 was primarily due to the growth in our subscription-based services.

For the trailing 12 months ended December 31, 2023, 2022 and 2021, our contract renewal rates for subscription-based services for contracts with a term of at least one year were approximately 90%, 90% and 92%, respectively; and, therefore, our cancellation rates for those services for the same periods were approximately 10%, 10% and 8%, respectively. Our contract renewal rate is a quantitative measurement that is typically closely correlated with our revenue results. As a result, we believe that the rate may be a reliable indicator of short-term and long-term performance absent extraordinary circumstances. Our trailing 12-month contract renewal rate may decline as a result of negative economic conditions, consolidations among our clients, reductions in customer spending or decreases in our customer base. Revenue from our subscription-based contracts with a term of at least one year were approximately 82%, 80% and 77% of total revenue for the trailing 12 months ended December 31, 2023, 2022 and 2021, respectively. The increase in the percentage of our revenue from subscription-based contracts for contracts with a term of at least one year from 2022 to 2023 was due to increases in sales of longer term advertising products. The decrease in the percentage of our revenue from subscription-based contracts with a term of at least one year from 2023 to 2022 was primarily due to the acquisitions of companies that contained a higher percentage of transaction-based revenue than our legacy businesses, as well as increases in sales of shorter term advertising products.

Development, Investments and Expansion

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We plan to continue to invest in our business and our services, evaluate strategic growth opportunities and pursue our key priorities as described below. We are committed to supporting, improving and enhancing our information, analytics and online marketplace solutions, including expanding and improving our offerings for our client base and site users, including property owners, property managers, buyers, commercial tenants and residential renters and buyers. We expect to continue our software development efforts to improve existing services, introduce new services, integrate and cross-sell services, integrate recently completed acquisitions and expand and develop supporting technologies for our research, sales and marketing organizations. We may reevaluate our priorities as economic conditions continue to evolve.

Our key priorities for the year ending December 31, 2024 currently include:

•Continuing to develop and invest in our residential marketplaces. For Homes.com we are creating additional content for neighborhoods, parks, schools and condos. In February 2024, we launched our new Homes.com subscription memberships to promote the home listing as well as the agent in the sort order on the website. We intend to create an expanded dedicated sales force, to supplement the efforts of our sales team already in place. We plan to increase our residential marketing investment, including the launch of a brand campaign.

For OnTheMarket, we plan to integrate OnTheMarket into the Company’s operations including additional investment in marketing, content creation and enhancing OnTheMarket’s website to improve performance and facilitate better search engine optimization.

•Continuing to enhance our facilities. We are expanding our research and technology center in Richmond, Virginia. We broke ground on the expansion in November 2022 and expect construction to be substantially completed in the first half of 2026. The expansion includes construction of two new buildings spanning 750,000 square feet and will bring our campus footprint to over 1 million square feet when completed. We plan to increase our research, technology, operations, software development, marketing and sales teams in this location.

In February 2024, we closed on the purchase of a building in Arlington, Virginia and we plan to build out a space for our employees. The lease on our current Washington, DC headquarters ends in 2025.

We expect our investment in these priorities will increase our research, selling and marketing and facilities expenses, including potential impairments of assets associated with the acquired building. Each of these will reduce our net income and may reduce our cash on hand for the year ending December 31, 2024 compared to the year ended December 31, 2023. We intend to continue to assess the need for additional investments in our business in order to develop and distribute new services and functionality within our current platform or expand the reach of, or otherwise improve, our current service offerings. Any future product development or expansion of services, combination and coordination of services or elimination of services or corporate expansion, development or restructuring efforts could reduce our profitability and increase our capital expenditures. Any new investments, changes to our service offerings or other unforeseen events could cause us to experience reduced revenues or generate losses and negative cash flow from operations in the future. Any development efforts must comply with our credit facility, which contains restrictive covenants that restrict our operations and use of our cash flow and may prevent us from taking certain actions that we believe could increase our profitability or otherwise enhance our business.

For further discussion of our Company, strategy and products, see our business overview set forth in "Item 1. Business" in this Report.

Impacts of Current Economic Conditions

In response to the concerns over inflation risk, the U.S. Federal Reserve raised interest rates over the past two years. It is currently unclear how the commercial real estate industry will ultimately be impacted by the current economic conditions. Rising interest rates or a period of elevated interest rates may reduce demand for all types of real estate. If the demand for office space or other real estate decreases significantly, there could be a downturn in the commercial real estate market that may materially adversely affect many of our clients. A depressed commercial real estate market would have a negative impact on our core customer base, which could impact our customers’ ability to subscribe and pay for our services and reduce demand for our services. Reduced demand and increased cancellations could cause our revenues or our revenue growth rates to decline and reduce our profitability.

Non-GAAP Financial Measures

We prepare and publicly release quarterly unaudited financial statements prepared in accordance with GAAP. We also disclose and discuss certain non-GAAP financial measures in our public releases, investor conference calls and filings with the SEC. The non-GAAP financial measures that we may disclose include EBITDA, adjusted EBITDA, adjusted EBITDA margin,

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non-GAAP net income and non-GAAP net income per diluted share. EBITDA is our net income before interest income or expense, net, other income or expense, net, loss on debt extinguishment, income taxes, depreciation and amortization. We typically disclose EBITDA on a consolidated and an operating segment basis in our earnings releases, investor conference calls and filings with the SEC. Adjusted EBITDA is different from EBITDA because we further adjust EBITDA for stock-based compensation expense, acquisition- and integration-related costs, restructuring costs and settlements and impairments incurred outside our ordinary course of business. Adjusted EBITDA margin represents adjusted EBITDA divided by revenues for the period. Non-GAAP net income is determined by adjusting our net income for stock-based compensation expense, acquisition- and integration-related costs, restructuring costs, settlement and impairment costs incurred outside our ordinary course of business and loss on debt extinguishment, as well as amortization of acquired intangible assets and other related costs, and then subtracting an assumed provision for income taxes. Non-GAAP net income per diluted share is a non-GAAP financial measure that represents non-GAAP net income divided by the number of diluted shares outstanding for the period used in the calculation of GAAP net income per diluted share.

We may disclose adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income and non-GAAP net income per diluted share on a consolidated basis in our earnings releases, investor conference calls and filings with the SEC. The non-GAAP financial measures that we use may not be comparable to similarly titled measures reported by other companies. Also, in the future, we may disclose different non-GAAP financial measures in order to help our investors meaningfully evaluate and compare our results of operations to our previously reported results of operations or to those of other companies in our industry.

We view EBITDA, adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income and non-GAAP net income per diluted share as operating performance measures. We believe that the most directly comparable GAAP financial measure to EBITDA, adjusted EBITDA and non-GAAP net income is net income. We believe the most directly comparable GAAP financial measures to non-GAAP net income per diluted share and adjusted EBITDA margin are net income per diluted share and net income divided by revenue, respectively. In calculating EBITDA, adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income and non-GAAP net income per diluted share, we exclude from net income the financial items that we believe should be separately identified to provide additional analysis of the financial components of the day-to-day operation of our business. We have outlined below the type and scope of these exclusions and the material limitations on the use of these non-GAAP financial measures as a result of these exclusions. EBITDA, adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income and non-GAAP net income per diluted share are not measurements of financial performance under GAAP and should not be considered as a measure of liquidity, as an alternative to net income or as an indicator of any other measure of performance derived in accordance with GAAP. Investors and potential investors in our securities should not rely on EBITDA, adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income and non-GAAP net income per diluted share as a substitute for any GAAP financial measure, including net income and net income per diluted share. In addition, we urge investors and potential investors in our securities to carefully review the GAAP financial information included as part of our Annual Reports on Form 10-K and Quarterly Reports on Form 10-Q that are filed with the SEC, as well as our quarterly earnings releases, and compare the GAAP financial information with our EBITDA, adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income and non-GAAP net income per diluted share.

EBITDA, adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income and non-GAAP net income per diluted share may be used by management to internally measure our operating and management performance and may be used by investors as supplemental financial measures to evaluate the performance of our business. We believe that these non-GAAP measures, when viewed with our GAAP results and accompanying reconciliations, provide additional information to investors that is useful to understand the factors and trends affecting our business without the impact of certain acquisition-related items. We have spent more than 30 years building our database of commercial real estate information and expanding our markets and services partially through acquisitions of complementary businesses. Due to these acquisitions, our net income has included significant charges for amortization of acquired intangible assets, depreciation and other amortization, acquisition- and integration-related costs, restructuring costs and loss on debt extinguishment. Adjusted EBITDA, adjusted EBITDA margin, non-GAAP net income and non-GAAP net income per diluted share exclude these charges and provide meaningful information about the operating performance of our business, apart from charges for amortization of acquired intangible assets, depreciation and other amortization, acquisition- and integration-related costs, restructuring costs; settlement and impairment costs incurred outside our ordinary course of business. We believe the disclosure of non-GAAP measures can help investors meaningfully evaluate and compare our performance from quarter-to-quarter and from year-to-year without the impact of these items. We also believe the non-GAAP measures we disclose are measures of our ongoing operating performance because the isolation of non-cash charges, such as amortization and depreciation, and other items, such as interest income or expense, net, other income or expense, net, income taxes, stock-based compensation expenses, acquisition- and integration-related costs, restructuring costs, loss on debt extinguishment and settlement and impairment costs incurred outside our ordinary course of business, provides additional information about our cost structure, and, over time, helps track our operating progress. In addition, investors, securities analysts and others have regularly relied on EBITDA and may rely on adjusted EBITDA, adjusted

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EBITDA margin, non-GAAP net income or non-GAAP net income per diluted share to provide a financial measure by which to compare our operating performance against that of other companies in our industry.

Set forth below are descriptions of financial items that have been excluded from net income to calculate EBITDA and the material limitations associated with using this non-GAAP financial measure as compared to net income:

•Amortization of acquired intangible assets in cost of revenues may be useful for investors to consider because it represents the diminishing value of any acquired trade names and other intangible assets and the use of our acquired technology, which is one of the sources of information for our database of commercial real estate information. We do not believe these charges necessarily reflect the current and ongoing cash charges related to our operating cost structure.

•Amortization of acquired intangible assets in operating expenses may be useful for investors to consider because it represents the estimated attrition of our acquired customer base. We do not believe these charges necessarily reflect the current and ongoing cash charges related to our operating cost structure.

•Depreciation and other amortization may be useful for investors to consider because they generally represent the wear and tear on our property and equipment used in our operations. We do not believe these charges necessarily reflect the current and ongoing cash charges related to our operating cost structure.

•The amount of interest income or expense, net and other income or expense, net we generate and incur may be useful for investors to consider and may result in current cash inflows and outflows. However, we do not consider the amount of interest income or expense, net and other income or expense, net to be a representative component of the day-to-day operating performance of our business.

•Income tax expense may be useful for investors to consider because it generally represents the taxes which may be payable for the period and the change in deferred income taxes during the period and may reduce the amount of funds otherwise available for use in our business. However, we do not consider the amount of income tax expense to be a representative component of the day-to-day operating performance of our business.

•The amount of loss on our debt extinguishment may be useful for investors to consider because it generally represents losses from the early extinguishment of debt. However, we do not consider the amount of the loss on debt extinguishment to be a representative component of the day-to-day operating performance of our business.

Set forth below are descriptions of additional financial items that have been excluded from EBITDA to calculate adjusted EBITDA and the material limitations associated with using this non-GAAP financial measure as compared to net income:

•Stock-based compensation expense may be useful for investors to consider because it represents a portion of the compensation of our employees and executives. Determining the fair value of the stock-based instruments involves a high degree of judgment and estimation and the expenses recorded may bear little resemblance to the actual value realized upon the future exercise or termination of the related stock-based awards. Therefore, we believe it is useful to exclude stock-based compensation in order to better understand the long-term performance of our core business.

•The amount of acquisition- and integration-related costs incurred may be useful for investors to consider because such costs generally represent professional service fees and direct expenses related to acquisitions. Because we do not acquire businesses on a predictable cycle, we do not consider the amount of acquisition- and integration-related costs to be a representative component of the day-to-day operating performance of our business.

•The amount of settlement and impairment costs incurred outside of our ordinary course of business may be useful for investors to consider because they generally represent gains or losses from the settlement of litigation matters, charges related to terminations of contracts or impairments of acquired intangible assets or other long lived assets. We do not believe these charges necessarily reflect the current and ongoing cash charges related to our operating cost structure.

•The amount of restructuring costs incurred may be useful for investors to consider because they generally represent costs incurred in connection with a change in a contract or a change in the makeup of our properties or personnel. Because we do not carry out restructuring activities on a predictable cycle, we do not consider the amount of restructuring related costs to be a representative component of the day-to-day operating performance of our business.

The financial items that have been excluded from our net income to calculate non-GAAP net income and non-GAAP net income per diluted share are amortization of acquired intangible assets and other related costs, stock-based compensation, acquisition- and integration-related costs, restructuring and related costs and settlement and impairment costs incurred outside

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our ordinary course of business. These items are discussed above with respect to the calculation of adjusted EBITDA together with the material limitations associated with using this non-GAAP financial measure as compared to net income. In addition to these exclusions from net income, we subtract an assumed provision for income taxes to calculate non-GAAP net income. In both 2023 and 2022, we assumed a 26% tax rate, which approximated our historical long-term statutory corporate tax rate, excluding the impact of discrete items.

Management compensates for the above-described limitations of using non-GAAP measures by using a non-GAAP measure only to supplement our GAAP results and to provide additional information that is useful to investors to understand the factors and trends affecting our business.

See Note 14 of the Notes to Consolidated Financial Statements included in Part IV of this Report for the reconciliation of our net income to our EBITDA.

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Consolidated Results of Operations

The following table provides our selected consolidated results of operations for the indicated periods (in millions and as a percentage of total revenue):

	Year Ended December 31,
	2023				2022				2021
Revenues	$	2,455.0	100	%	$	2,182.4	100	%	$	1,944.1	100	%
Cost of revenues	491.5		20		414.0		19		357.2		18
Gross profit	1,963.5		80		1,768.4		81		1,586.9		82
Operating expenses:
Selling and marketing (excluding customer base amortization)	989.9		40		684.2		31		622.0		32
Software development	267.6		11		220.9		10		201.0		10
General and administrative	381.5		16		338.7		16		256.8		13
Customer base amortization	42.2		2		73.6		3		74.8		4
Total operating expenses(1)	1,681.2		68		1,317.4		60		1,154.6		59
Income from operations(1)	282.3		11		451.0		21		432.3		22
Interest income (expense), net	213.6		9		32.1		1		(31.6)		(2)
Other income, net	5.4		—		3.4		—		3.3		—
Income before income taxes(1)	501.3		20		486.5		22		404.0		21
Income tax expense	126.6		5		117.0		5		111.4		6
Net income(1)	$	374.7	15	%	$	369.5	17	%	$	292.6	15	%
__________________________

(1) Amounts may not foot due to rounding.

The following table provides our revenues by type of service (in millions and as a percentage of total revenue):

	Year Ended December 31,
	2023				2022				2021
CoStar	$	925.2	38	%	$	837.0	38	%	$	722.8	37	%
Information services	170.9		7		157.4		7		141.7		7
Multifamily	914.2		37		745.4		34		678.7		35
LoopNet	264.8		11		230.9		11		207.5		11
Residential	46.1		2		73.7		3		74.6		4
Other marketplaces	133.8		5		138.0		6		118.8		6
Total revenues(1)(2)	$	2,455.0	100	%	$	2,182.4	100	%	$	1,944.1	100	%
__________________________

(1) For further discussion of our Company, strategy and products, see our business overview set forth in "Item 1. Business" in this Report.
(2) Totals may not foot due to rounding.

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Comparison of Year Ended December 31, 2023 and Year Ended December 31, 2022

The following table provides a comparison of our selected consolidated results of operations for the years ended December 31, 2023 and 2022 (in millions):

	2023		2022		Increase (Decrease)		Increase (Decrease)
Revenues:
CoStar	$	925.2	$	837.0	$	88.2	10.5	%
Information services	170.9		157.4		13.5		8.6
Multifamily	914.2		745.4		168.8		22.6
LoopNet	264.8		230.9		33.9		14.7
Residential	46.1		73.7		(27.6)		(37.4)
Other marketplaces	133.8		138.0		(4.2)		(3.0)
Total revenues	2,455.0		2,182.4		272.6		12.5
Cost of revenues	491.5		414.0		77.5		18.7
Gross profit	1,963.5		1,768.4		195.1		11.0
Operating expenses:
Selling and marketing (excluding customer base amortization)	989.9		684.2		305.7		44.7
Software development	267.6		220.9		46.7		21.1
General and administrative	381.5		338.7		42.8		12.6
Customer base amortization	42.2		73.6		(31.4)		(42.7)
Total operating expenses	1,681.2		1,317.4		363.8		27.6
Income from operations	282.3		451.0		(168.7)		(37.4)
Interest income, net	213.6		32.1		181.5		565.4
Other income, net	5.4		3.4		2.0		58.8
Income before income taxes	501.3		486.5		14.8		3.0
Income tax expense	126.6		117.0		9.6		8.2
Net income	$	374.7	$	369.5	$	5.2	1.4	%

Revenues. Revenues increased $273 million, or 12.5%, to $2.5 billion. The increase in our revenues included:

•an increase in Multifamily revenues of $169 million, or 22.6%, due to higher sales volume driven by an increase in the number of properties listed on our network and increases in pricing on renewals,

•an increase in CoStar revenues of $88 million, or 10.5%, due to higher sales volume driven by the impact of annual price increases and customer upgrades on contract renewals, as well as an increase in subscribers,

•an increase in LoopNet revenues of $34 million, or 14.7%, due to an increase in the average price for listings,

•an increase in Information services revenues of $14 million, or 8.6%, primarily attributable to an increase in revenues for STR of $7 million, CoStar Real Estate Manager of $5 million and $2 million of revenue related to the Business Immo Acquisition,

•a decrease in Residential revenues of $28 million, or 37.4%, due to the discontinuation of certain products and services that were inconsistent with our long-term business strategy partially offset by $2 million of revenue related to the OnTheMarket Acquisition and

•a decrease in Other marketplaces revenues of $4 million, or 3.0%, due to lower property volumes auctioned on Ten-X partially offset by increases in revenue of Land.com.

Gross Profit and Cost of Revenues. Gross profit increased $195 million, or 11.0%, to $2.0 billion in 2023, and the gross profit percentage decreased from 81% to 80%. The increase in gross profit was due to higher revenues partially offset by an increase in the cost of revenues. Cost of revenues increased $78 million, or 18.7% to $492 million and, as a percentage of revenues, increased from 19% to 20%. The increase in cost of revenues included:

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•an increase in personnel costs of $61 million related to rising headcount to support our residential research efforts, and increases in salaries, bonus, stock-based compensation and benefits costs for our existing employees,

•an increase of $25 million in technology costs to host our database and products and

•an decrease of $11 million in expenses related to advertising purchased on behalf of customers.

Selling and Marketing Expenses. Selling and marketing expenses increased $306 million, or 44.7%, to $990 million and, as a percentage of revenues, increased from 31% to 40%. The increase included:

•an increase in marketing expenses of $244 million for advertising our brands,

•an increase in personnel and events costs of $63 million related to rising headcount in our sales force and increases in salaries, bonus, stock-based compensation and benefits costs for our existing employees and

Software Development Expenses. Software development expenses increased $47 million, or 21.1% to $268 million and, as a percentage of revenues, increased from 10% to 11%. The increase primarily included higher personnel costs of $42 million related to rising headcount to support our residential efforts and increases in salaries, bonus, stock-based compensation and benefits costs for our existing employees.

General and Administrative Expenses. General and administrative expenses increased $43 million, or 12.6%, to $382 million and, as a percentage of revenues, was consistent at 16%. The increase included:

•an increase of $17 million in credit loss expense primarily due to our expectations that the downturn in the commercial real estate market will increase delinquent trade receivables,

•an increase of $19 million in professional service costs due to diligence efforts associated with potential acquisitions and legal fees to defend our intellectual property rights and

•an increase of $11 million in personnel costs related to increases in salaries, bonus, stock-based compensation and benefits costs for our existing employees and rising headcount.

Customer Base Amortization Expense. Customer base amortization expense decreased $31 million, or 42.7%, to $42 million and, as a percentage of revenues, decreased from 3% to 2%. The decrease was primarily attributable to acceleration of amortization of $16 million related to eliminating certain usage fees for agent access to the Homesnap product recorded in 2022, as well as a reduction in amortization expense related to customer base assets acquired in the acquisitions of LoopNet, ForRent and Ten-X, which have been amortizing on an accelerated basis since the respective acquisitions.

Interest Income, Net. Interest income, net increased $182 million, or 565.4%, to $214 million due to an increase in interest earned on our cash equivalents.

Other Income, Net. Other income, net was insignificant for both the years ended December 31, 2023, and 2022.

Income Tax Expense. Income tax expense increased $10 million, or 8.2%, to $127 million and the effective tax rate increased 1% to 25% of income before income taxes. The increase in income tax expense was primarily attributable to additional income before income taxes and a benefit recognized in 2022 for state tax credits.

For a comparison of our results of operations for the fiscal year ended December 31, 2022 to the year ended December 31, 2021, see Item 7, Management’s Discussion and Analysis of Financial Condition and Results of Operations in our Annual Report on the Form 10-K for the year ended December 31, 2022, which was filed with the SEC on February 22, 2023.

Comparison of Business Segment Results for Year Ended December 31, 2023 and Year Ended December 31, 2022

We manage our business geographically in two operating segments, with the primary areas of measurement and decision-making being North America, which includes the U.S. and Canada, and International, which primarily includes Europe, Asia-Pacific and Latin America. Management relies on an internal management reporting process that provides revenue and operating segment EBITDA, which is our net income before interest income or expense, net, other income or expense, net, loss on debt extinguishment, income taxes, depreciation and amortization. Management believes that operating segment EBITDA is an appropriate measure for evaluating the operational performance of our operating segments. EBITDA is used by management to internally measure operating and management performance and to evaluate the performance of our business.

Segment Revenues. North America revenues increased $260 million, or 12.3%, to $2.4 billion and included:

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•an increase in CoStar revenues of $86 million, or 10.7%, due to higher sales volume driven by the impact of annual price increases and customer upgrades on contract renewals, as well as an increase in subscribers,

•an increase in Information services revenues of $7 million, or 5.9%, primarily attributable to an increase in revenues for CoStar Real Estate Manager of $5 million and STR of $3 million,

•an increase in Multifamily revenues of $169 million, or 22.7%, due to higher sales volume driven by increases in pricing on renewals and an increase in the number of properties listed on our network,

•an increase in LoopNet revenues of $32 million, or 14.2%, due to an increase in the average price for listings,

•a decrease in Residential revenues of $30 million, or 40.4%, due to the discontinuation of certain products and services that were inconsistent with our long-term business strategy and

•a decrease in Other marketplaces revenues of $4 million, or 3.0%, due to the lower property volumes auctioned on Ten-X partially offset by increases in revenue of Land.com..

International revenues increased $13 million, or 16.9%, to $89 million and primarily included:

•an increase in Information services revenues of $6 million, or 18.8%, primarily attributable to an increase in revenues for STR of $4 million and $2 million of revenue related to the Business Immo Acquisition,

•an increase in CoStar revenues of $2 million, or 6.5%, due to higher sales volume driven by the impact of annual price increases and customer upgrades on contract renewals, as well as an increase in subscribers,

•an increase in LoopNet revenues of $2 million, or 30.6%, due to an increase in the average price for listings and

•$2 million of revenue related to the OnTheMarket Acquisition.

Segment EBITDA. North America EBITDA decreased to $403 million for the year ended December 31, 2023, from $577 million for the year ended December 31, 2022. The decrease in North America EBITDA was primarily due to increases in personnel costs, marketing costs, technology hosting costs, professional service fees, sales events costs, credit loss expense and occupancy costs partially offset by increases in revenues described above. International EBITDA decreased to a loss of $13 million for the year ended December 31, 2023 from $5 million for the year ended December 31, 2022. The decrease was due to increased personnel costs, partially offset by, an increase in revenue.

For a comparison of our business segment results of operations for the fiscal year ended December 31, 2022 to the year ended December 31, 2021, see Item 7, Management’s Discussion and Analysis of Financial Condition and Results of Operations in our Annual Report on Form 10-K for the year ended December 31, 2022, which was filed with the SEC on February 22, 2023.

Liquidity and Capital Resources

We believe the balance of cash and cash equivalents, which was $5.2 billion as of December 31, 2023, along with cash generated by ongoing operations and continued access to capital markets, will be sufficient to satisfy our cash requirements over the next 12 months and beyond. Our material cash requirements include the following contractual and other obligations.

Debt. As of December 31, 2023, we had outstanding an aggregate principal amount of $1.0 billion of Senior Notes due July 15, 2030. Future interest payments associated with the Senior Notes are $196.0 million, with $28.0 million payable within 12 months.

Leases. We have lease arrangements for office facilities, data centers and certain vehicles. As of December 31, 2023, we had fixed lease payment obligations of $110 million, with $39 million payable within 12 months.

Purchase Obligations. Our purchase obligations are associated with agreements that are enforceable and legally binding and that specify all significant terms, including fixed or minimum services to be used, fixed, minimum or variable price provisions, and the approximate timing of the transaction and have an original term greater than one year. The services acquired under these agreements primarily relate to web hosting, sponsorship agreements, third-party data or listings and software subscriptions. As of December 31, 2023, we had purchase obligations of $264 million, with $81 million payable within 12 months.

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Construction Commitments. We are expanding our Richmond, Virginia campus, which is expected to result in material cash requirements in 2024 and beyond. We broke ground on the expansion in November 2022 and expect construction to be substantially completed in the first half of 2026. We negotiated various tax incentives with the Commonwealth of Virginia and the City of Richmond including the allowance to use market-based income apportionment for income taxes and partial reimbursements of property tax assessments related to the value of the campus expansion. These incentives are conditional upon achieving job creation and capital expenditure targets from 2022 to 2029. Failure to meet these targets could result in a reduction of the value of the tax incentives and repayment of previous tax reductions. The value of the incentives is dependent on our taxable income.

We expect the total cost of construction, net of the estimated value of the tax incentives from 2023 to 2032, to be in the range of $450 – $600 million. We have engaged a project manager, architects and a general contractor on terms that generally require payments as services are provided or construction is performed. As of December 31, 2023, we have paid $128 million and we have committed to spend an additional $437 million as further work is performed under these contracts. We plan to amend these contracts to include additional commitments as construction progresses. Total cash expenditures for 2024 are expected to be approximately $385 million. We expect to fund the expansion with cash on hand.

In January 2024, the Company entered into a conditional purchase and sale agreement for an office building in Arlington, Virginia. The Company closed on the transaction in February 2024 along with an agreement to purchase the land underlying the building. These transactions totaled $340.0 million, inclusive of property taxes, titling insurance and other transaction costs and were paid with cash on hand.

Our future capital requirements will depend on many factors, including, among others, our operating results, expansion and integration efforts and our level of acquisition activity or other strategic transactions. To date, we have grown in part by acquiring other companies, and we expect to continue to make acquisitions.

Cash and cash equivalents increased to $5.2 billion as of December 31, 2023, compared to cash and cash equivalents of $5.0 billion as of December 31, 2022. The increase in cash and cash equivalents for the year ended December 31, 2023 was primarily due to cash flow from operations of $489.5 million, partially offset by spending on capital assets

Net cash provided by operating activities for the year ended December 31, 2023 was $489.5 million compared to $478.7 million for the year ended December 31, 2022. The $10.8 million increase was primarily due to higher net income, excluding certain non-cash expenses.

Net cash used in investing activities for the year ended December 31, 2023 was $238.6 million compared to $69.1 million for the year ended December 31, 2022. The change was primarily due to an increase in cash paid for acquisitions of $93.3 million, increased spending for the Richmond campus of $82.3 million, and a decrease in proceeds from sale of property and equipment and other assets of $30.1 million.

Net cash used in financing activities for the year ended December 31, 2023 was $3.7 million compared to net cash provided by financing activities of $734.0 million for the year ended December 31, 2022. The change was primarily due to $745.7 million of net proceeds from our September 2022 equity offering.

Critical Accounting Estimates

The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and revenues and expenses during the period reported. The following accounting policies involve a “critical accounting estimate” because they are particularly dependent on estimates and assumptions made by management about matters that are highly uncertain at the time the accounting estimates are made. In addition, while we have used our best estimates based on facts and circumstances available to us at the time, different acceptable assumptions would yield different results. Changes in the accounting estimates are reasonably likely to occur from period to period, which may have a material impact on the presentation of our financial condition and results of operations. We review these estimates and assumptions periodically and reflect the effects of revisions in the period that they are determined to be necessary. We consider policies relating to the following matters to be critical accounting policies:

•Intangible assets and goodwill;

•Income taxes;

•Revenue recognition; and

•Business combinations.

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With respect to our accounting policy for intangible assets and goodwill, we further supplement in Note 2 of the Notes to the Consolidated Financial Statements included in Part IV of this Report with the following:

We assess the impairment of identifiable intangibles and goodwill whenever events or changes in circumstances indicate that the carrying value may not be recoverable. Judgments made by management relate to the expected useful lives of intangible assets and our ability to recover the carrying value of such assets. The accuracy of these judgments may be adversely affected by several factors, including the factors listed below:

•Significant underperformance relative to historical or projected future operating results;

•Significant changes in the manner of our use of the acquired assets or the strategy for our overall business;

•Significant negative industry or economic trends; or

•Significant decline in our market capitalization relative to net book value for a sustained period.

When we determine that the carrying value of intangible assets may not be recovered based upon the existence of one or more of the above indicators, we test for impairment.

Goodwill and identifiable intangible assets that are not subject to amortization are tested annually for impairment by each reporting unit on October 1 of each year and are also tested for impairment more frequently based upon the existence of one or more of the above indicators.

Goodwill represents the future economic benefits arising from a business combination and is calculated as the excess of purchase consideration paid in a business combination over the fair value of assets of the net identifiable assets acquired. Goodwill is not amortized, but instead tested for impairment at least annually by each reporting unit, or more frequently if an event or other circumstance indicates that the fair value of a reporting unit may be below its carrying amount. We may first assess qualitative factors to evaluate whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or elect to bypass the qualitative assessment. If it is determined that it is more likely than not that the fair value of a reporting unit is less than its carrying value, or we elect to bypass the qualitative assessment, we then perform a quantitative assessment by determining the fair value of each reporting unit. We estimate the fair value of each reporting unit based on a projected discounted cash flow model that includes significant assumptions and estimates including our discount rate, growth rate and future financial performance. Assumptions about the discount rate are based on a weighted average cost of capital for comparable companies and determined by management to be commensurate with the risk in our current business model. Assumptions about the growth rate and future financial performance of a reporting unit are based on our forecasts, business plans, economic projections and anticipated future cash flows. These assumptions are subject to change from period-to-period and could be adversely impacted by the uncertainty surrounding global market conditions, commercial real estate conditions and the competitive environment in which we operate. Changes in these or other factors could negatively affect our reporting units' fair value and potentially result in impairment charges. Such impairment charges could have an adverse effect on our results of operations. The fair value of each reporting unit is compared to the carrying amount of the reporting unit. If the carrying value of the reporting unit exceeds the fair value, then an impairment loss is recognized for the difference.

As of October 1, 2023, we assessed the relevant qualitative factors for our North America reporting unit and concluded that it was not more likely than not that the fair value of this reporting unit was less than its respective carrying amounts. We elected to bypass performing the qualitative screen and performed the first step quantitative analysis of the goodwill impairment test for our International reporting unit in 2023, which indicated that the fair value of this unit exceeded its carrying value. There have been no events or changes in circumstances as a result of our qualitative impairment analysis on October 1, 2023, that would indicate that the carrying value of each reporting unit may not be recoverable.

For an in-depth discussion of each of our significant accounting policies, including our critical accounting policies and further information regarding estimates and assumptions involved in their application, see Note 2 of the Notes to the Consolidated Financial Statements included in Part IV of this Report.

Recent Accounting Pronouncements

See Note 2 of the Notes to the Consolidated Financial Statements included in this Report for further discussion of recent accounting pronouncements, including the expected dates of adoption.

Item 7A.    Quantitative and Qualitative Disclosures About Market Risk

We provide information, analytics and online marketplace services to commercial real estate and related business communities within the regions where we operate which primarily include, North America, Europe, Asia-Pacific and Latin

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America. The functional currency for a majority of our operations is the local currency, with the exception of certain international locations for which the functional currency is the British Pound.

Fluctuations in the British Pound, Canadian dollar and Euro may have an impact on our business, results of operations and financial position. For both the years ended December 31, 2023 and December 31, 2022, revenues denominated in foreign currencies were approximately 4%, of total revenue. For the years ended December 31, 2023 and December 31, 2022, our revenues would have decreased by approximately $10 million and $8 million, respectively, if the U.S. dollar exchange rate used strengthened by 10%. For the years ended December 31, 2023 and December 31, 2022, our revenues would have increased by approximately 4% and $8 million, respectively, if the U.S. dollar exchange rate used weakened by 10%. Fluctuations in the exchange rates of revenues denominated in any other foreign currencies would have had an immaterial impact on our consolidated results. In addition, we have assets and liabilities denominated in foreign currencies. We currently do not use financial instruments to hedge our exposure to exchange rate fluctuations with respect to our foreign subsidiaries. We may seek to enter into hedging transactions in the future to reduce our exposure to exchange rate fluctuations, but we may be unable to enter into hedging transactions successfully, on acceptable terms or at all. As of December 31, 2023, accumulated other comprehensive loss included a loss from foreign currency translation adjustments of approximately $17.6 million.

We do not believe we have material exposure to market risks associated with changes in interest rates related to cash equivalent securities held as of December 31, 2023. As of December 31, 2023, we had of cash and cash equivalents. If there is an increase or decrease in interest rates, there will be a corresponding increase or decrease in the amount of interest earned on our cash and cash equivalents. We currently diversify our cash and cash equivalents holdings amongst multiple financial institutions and AAA-rated Government and Treasury Money Market Funds.

We are subject to interest rate market risk in connection with our revolving credit facility. On July 1, 2020, we entered into the 2020 Credit Agreement, which provides for variable rate borrowings of up to $750 million. On July 1, 2020, we issued $1.0 billion aggregate principal amount of Senior Notes. Changes in interest rates would not have a material impact to our current interest and debt financing expense, as all of our borrowings except for our credit facility are fixed rate, and no amounts were outstanding under our credit facility as of December 31, 2023. See Note 11 of the Notes to the Consolidated Financial Statements included in this Report for additional information regarding our 2020 Credit Agreement.

We had approximately $2.7 billion of goodwill and intangible assets as of December 31, 2023. As of December 31, 2023, we believe our intangible assets will be recoverable; however, changes in the economy, the business in which we operate and our own relative performance could change the assumptions used to evaluate intangible asset recoverability. In the event that we determine that an asset has been impaired, we would recognize an impairment charge equal to the amount by which the carrying amount of the assets exceeds the fair value of the asset. We continue to monitor these assumptions and their effect on the estimated recoverability of our intangible assets.

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Item 8.    Financial Statements and Supplementary Data

Financial Statements meeting the requirements of Regulation S-X, including reports of independent registered public accounting firm Ernst & Young LLP, are set forth beginning at page F-1. Supplementary data is set forth in “Management’s Discussion and Analysis of Financial Condition and Results of Operations” under the caption “Consolidated Results of Operations.”

Item 9.    Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

None.

Item 9A.    Controls and Procedures

We maintain disclosure controls and procedures that are designed to ensure that information required to be disclosed in our reports filed or submitted under the Securities Exchange Act of 1934, as amended, is recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms, and that such information is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate, to allow for timely decisions regarding required disclosure. In designing and evaluating the disclosure controls and procedures, management recognized that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving the desired control objectives, and management is required to apply its judgment in evaluating the cost-benefit relationship of possible controls and procedures.

As of December 31, 2023, we carried out an evaluation, under the supervision and with the participation of our management, including our Chief Executive Officer and our Chief Financial Officer, of the effectiveness of the design and operation of our disclosure controls and procedures as of the end of the fiscal year. Based on the foregoing, our Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures were effective as of December 31, 2023 and were operating at a reasonable assurance level.

We continue to implement a financial system that is designed to improve the efficiency and effectiveness of our operational and financial accounting processes. This implementation is expected to be a multi-year project. Consistent with any process change that we implement, the design of the internal controls has and will continue to be evaluated for effectiveness as part of our overall assessment of the effectiveness of our disclosure controls and procedures. We expect that the implementation of this system will improve our internal control over financial reporting.

Other than the implementation of a new financial system noted above, there have been no changes in our internal control over financial reporting during our most recent fiscal quarter that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Management’s Report on Internal Control over Financial Reporting

Management of CoStar Group is responsible for establishing and maintaining adequate internal control over financial reporting and for the assessment of the effectiveness of internal control over financial reporting. As defined by the SEC, internal control over financial reporting is a process designed by, or supervised by, the Company’s principal executive and principal financial officers, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements in accordance with GAAP.

The Company’s internal control over financial reporting is supported by written policies and procedures, which (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the Company’s assets; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with GAAP, and that receipts and expenditures of the Company are being made only in accordance with authorizations of the Company’s management and directors; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use or disposition of the Company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

In connection with the preparation of the Company's annual financial statements, management of the Company has undertaken an assessment of the effectiveness of the Company’s internal control over financial reporting as of December 31, 2023 based on criteria established in Internal Control – Integrated Framework (2013 framework) issued by the Committee of

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Sponsoring Organizations of the Treadway Commission. Management's assessment included an evaluation of the design of the Company's internal control over financial reporting and testing of the operational effectiveness of the Company's internal control over financial reporting.

Based on this assessment, management has concluded that the Company's internal control over financial reporting was effective as of December 31, 2023.

Ernst & Young LLP, the independent registered public accounting firm that audited the Company's financial statements included in this report, has issued an attestation report on the effectiveness of internal control over financial reporting, a copy of which is included in this Report.

In December 2023, we completed the OnTheMarket Acquisition. As permitted by the SEC, we have elected to exclude the internal controls of this acquisition, which has not been integrated into our existing processes and controls, from our assessment of the effectiveness of internal control over financial reporting as of December 31, 2023. The excluded financial position of OnTheMarket represented less than 1% of our total assets as of December 31, 2023, and less than 1% of our revenues and total operating costs for the year then ended. We will include the internal controls of OnTheMarket in our assessment of the effectiveness of our internal control over financial reporting as of December 31, 2024.

Item 9B.    Other Information.

None.

Item 9C.    Disclosure Regarding Foreign Jurisdictions that Prevent Inspections.

Not applicable.

PART III

Item 10.    Directors, Executive Officers and Corporate Governance

CoStar Group has adopted a Code of Conduct for its directors. In addition, CoStar Group has adopted a separate Code of Business Conduct and Ethics for its officers and employees, including its principal executive, financial and accounting officers, or persons performing similar functions. Copies of each of these codes may be found in the “Investors” section of the Company’s website at https://investors.costargroup.com/leadership. We intend to disclose future amendments to certain provisions of our Codes, or waivers of such provisions granted to executive officers and directors, as required by the SEC rules on the Company's website within four business days following the date of such amendment or waiver.

The remaining information required by this Item is incorporated by reference to our Proxy Statement for our 2024 annual meeting of stockholders under the captions “Director Nominees,” “Executive Officers,” Corporate Governance Highlights,” “Board Committees,” “Insider trading arrangements and policies,” and, if applicable, “Delinquent Section 16(a) Reports.”

Item 11.    Executive Compensation

The information required by this Item is incorporated by reference to our Proxy Statement for our 2024 annual meeting of stockholders under the captions “Compensation Discussion and Analysis,” “Director Compensation,” “Compensation Committee Interlocks and Insider Participation,” and “Compensation Committee Report.”

Item 12.    Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

The information required by this Item is incorporated by reference to our Proxy Statement for our 2024 annual meeting of stockholders under the captions “Equity Compensation Plan Information” and “Stock Ownership Information.”

Item 13.    Certain Relationships and Related Transactions, and Director Independence

The information required by this Item is incorporated by reference to our Proxy Statement for our 2024 annual meeting of stockholders under the captions “Certain Relationships and Related Transactions” and “Corporate Governance Matters.”

Item 14.    Principal Accountant Fees and Services

The information required by this Item is incorporated by reference to our Proxy Statement for our 2024 annual meeting of stockholders under the caption “Ratification of the Appointment of Independent Registered Public Accounting Firm.”

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PART IV

Item 15.    Exhibits and Financial Statement Schedules

(a)(1) The following financial statements are filed as a part of this Report: CoStar Group, Inc. Consolidated Financial Statements.

(a)(2) Financial statement schedules: Additional financial statement schedules are omitted because they are not applicable or not required or because the required information is incorporated herein by reference or included in the financial statements or related notes included elsewhere in this report.

(a)(3) The documents required to be filed as exhibits to this Report under Item 601 of Regulation S-K are listed as follows:

Exhibits

Exhibit No.	Description
3.1	Fourth Amended and Restated Certificate of Incorporation of CoStar Group, Inc. (Incorporated by reference to Exhibit 3.1 to the Registrant's Current Report on Form 8-K filed with the SEC on June 7, 2021).
3.2	Fourth Amended and Restated By-Laws of CoStar Group, Inc. (Incorporated by reference to Exhibit 3.1 to the Registrant’s Current Report on Form 8-K filed with the SEC on May 9, 2022).
4.1	Specimen Common Stock Certificate (Incorporated by reference to Exhibit 4.1 to the Registration Statement on Form S-4 of the Registrant (Reg. No. 333-174214) filed with the SEC on June 3, 2011).
4.2	Description of the Registrant's Securities Registered Pursuant to Section 12 of the Securities Exchange Act of 1934 (Incorporated by reference to Exhibit 4.2 to the Registrant's Annual Report on Form 10-K filed with the SEC on February 23, 2022).
4.3	Indenture, dated as of July 1, 2020, by and among CoStar Group, Inc., as issuer, the guarantors named therein and Wilmington Trust, National Association, as trustee, relating to the 2.800% Senior Notes due 2030, including the form of 2.800% Senior Notes due 2030 (Incorporated by reference to Exhibit 4.1 to the Registrant’s Current Report on Form 8-K filed with the SEC on July 1, 2020).
*10.1	CoStar Group, Inc. 2016 Stock Incentive Plan (Incorporated by reference to Exhibit 4.4 to the Registration Statement on Form S-8 of the Registrant (Reg. No. 333-212278) filed with the SEC on June 28, 2016).
*10.2	First Amendment to the CoStar Group, Inc. 2016 Stock Incentive Plan (Incorporated by reference to Exhibit 10.1 to the Registrant’s Quarterly Report on Form 10-Q filed April 25, 2018).
*10.3	CoStar Group, Inc. 2007 Stock Incentive Plan, as amended (Incorporated by reference to Exhibit 10.1 to the Registrant’s Current Report on Form 8-K filed June 8, 2012).
*10.4	CoStar Group, Inc. 2007 Stock Incentive Plan French Sub-Plan (Incorporated by reference to Exhibit 10.3 to the Registrant’s Report on Form 10-K filed February 29, 2008).
*10.5	Form of CoStar Group, Inc. 2016 Plan Restricted Stock Grant Agreement between the Registrant and certain of its officers, directors and employees (Incorporated by reference to Exhibit 10.3 to the Registrant’s Quarterly Report on Form 10-Q filed July 28, 2016).
*10.6	Form of CoStar Group, Inc. 2016 Plan Restricted Stock Grant Agreement for Service Awards between the Registrant and certain of its officers and employees (Incorporated by reference to Exhibit 10.4 to the Registrant’s Quarterly Report on Form 10-Q filed July 28, 2016).
*10.7	Form of CoStar Group, Inc. 2016 Plan Restricted Stock Unit Grant Agreement between the Registrant and certain of its officers and employees (Incorporated by reference to Exhibit 10.5 to the Registrant’s Quarterly Report on Form 10-Q filed July 28, 2016).
*10.8	Form of CoStar Group, Inc. 2016 Plan Incentive Stock Option Grant Agreement between the Registrant and certain of its officers and employees (Incorporated by reference to Exhibit 10.6 to the Registrant’s Quarterly Report on Form 10-Q filed July 28, 2016).
*10.9	Form of CoStar Group, Inc. 2016 Plan Incentive Stock Option Grant Agreement between the Registrant and Andrew C. Florance (Incorporated by reference to Exhibit 10.7 to the Registrant’s Quarterly Report on Form 10-Q filed July 28, 2016).
*10.10	Form of CoStar Group, Inc. 2016 Plan Nonqualified Stock Option Grant Agreement between the Registrant and certain of its officers, directors and employees (Incorporated by reference to Exhibit 10.8 to the Registrant’s Quarterly Report on Form 10-Q filed July 28, 2016).

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Exhibit No.	Description
*10.11	Form of CoStar Group, Inc. 2016 Plan Nonqualified Stock Option Grant Agreement between the Registrant and Andrew C. Florance (Incorporated by reference to Exhibit 10.9 to the Registrant’s Quarterly Report on Form 10-Q filed July 28, 2016).
*10.12	Form of 2007 Plan Restricted Stock Grant Agreement between the Registrant and certain of its officers, directors and employees (Incorporated by reference to Exhibit 99.1 to the Registrant’s Current Report on Form 8-K filed June 22, 2007).
*10.13	Form of 2007 Plan Restricted Stock Unit Agreement between the Registrant and certain of its officers and employees (Incorporated by reference to Exhibit 10.8 to the Registrant's Annual Report on Form 10-K filed February 20, 2014).
*10.14	Form of 2007 Plan Incentive Stock Option Grant Agreement between the Registrant and certain of its officers and employees (Incorporated by reference to Exhibit 10.8 to the Registrant’s Annual Report on Form 10-K filed February 24, 2009).
*10.15	Form of 2007 Plan Incentive Stock Option Grant Agreement between the Registrant and Andrew C. Florance (Incorporated by reference to Exhibit 10.9 to the Registrant’s Annual Report on Form 10-K filed February 24, 2009).
*10.16	Form of 2007 Plan Nonqualified Stock Option Grant Agreement between the Registrant and certain of its officers and employees (Incorporated by reference to Exhibit 10.10 to the Registrant’s Annual Report on Form 10-K filed February 24, 2009).
*10.17	Form of 2007 Plan Nonqualified Stock Option Grant Agreement between the Registrant and certain of its directors (Incorporated by reference to Exhibit 10.11 to the Registrant’s Annual Report on Form 10-K filed February 24, 2009).
*10.18	Form of 2007 Plan Nonqualified Stock Option Grant Agreement between the Registrant and Andrew C. Florance (Incorporated by reference to Exhibit 10.12 to the Registrant’s Annual Report on Form 10-K filed February 24, 2009).
*10.19	Form of 2007 Plan French Sub-Plan Restricted Stock Agreement between the Registrant and certain of its employees (Incorporated by reference to Exhibit 10.10 to the Registrant’s Annual Report on Form 10-K filed February 29, 2008).
*10.20	CoStar Group, Inc. 2016 Cash Incentive Plan (Incorporated by reference to Exhibit 10.2 to the Registrant’s Quarterly Report on Form 10-Q filed July 28, 2016).
*10.21	Second Amended and Restated Employee Stock Purchase Plan (Incorporated by reference to Exhibit 4.4 to the Registrant’s Registration Statement on Form S-8 (No. 333-258220) filed with the SEC on July 28, 2021).
*10.22	Canadian Addendum to CoStar Group ESPP (filed herewith).
*10.23	CoStar Group, Inc. Management Stock Purchase Plan (Incorporated by reference to Exhibit 10.21 to the Registrant’s Annual Report on Form 10-K filed February 23, 2018).
*10.24	Summary of Non-Employee Director Compensation (Incorporated by reference to Exhibit 10.1 to the Registrant's Quarterly Report on Form 10-Q filed on October 24, 2013).
*10.25	Employment Agreement for Andrew C. Florance (Incorporated by reference to Exhibit 10.2 to Amendment No. 1 to the Registrant's Registration Statement on Form S-1 (Reg. No. 333-47953) filed with the SEC on April 27, 1998).
*10.26	First Amendment to Andrew C. Florance Employment Agreement, effective January 1, 2009 (Incorporated by reference to Exhibit 10.16 to the Registrant’s Annual Report on Form 10-K filed February 24, 2009).
10.27	Form of Indemnification Agreement between the Registrant and each of its officers and directors (Incorporated by reference to Exhibit 10.1 to the Registrant’s Quarterly Report on Form 10-Q filed on May 7, 2004).
10.28	Deed of Office Lease by and between GLL L-Street 1331, LLC and CoStar Realty Information, Inc., dated February 18, 2011, and made effective as of June 1, 2010 (Incorporated by reference to Exhibit 10.1 to the Registrant’s Quarterly Report on form 10-Q filed on April 29, 2011).
10.29	Second Amended and Restated Credit Agreement, dated as of July 1, 2020, by and among CoStar Group, Inc., as borrower, CoStar Realty Information, Inc., as co-borrower, the lenders party thereto and Bank of America, N.A., as administrative agent (Incorporated by reference to Exhibit 10.1 to the Registrant’s Current Report on Form 8-K filed with the SEC on July 1, 2020)
10.30	First Amendment to the Second Amended and Restated Credit Agreement, dated as of May 8, 2023, among CoStar Group, Inc., as borrower, CoStar Realty Information, Inc., as co-borrower, the lenders from time to time party thereto and Bank of America, N.A., as administrative agent (Incorporated by reference to Exhibit 10.1 to the Registrant’s Quarterly Report on Form 10-Q filed July 26, 2023)
21.1	Subsidiaries of the Registrant (filed herewith).
23.1	Consent of Ernst & Young LLP, Independent Registered Public Accounting Firm (filed herewith).

54

Exhibit No.	Description
31.1	Certification of Principal Executive Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 (filed herewith).
31.2	Certification of Principal Financial Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002 (filed herewith).
32.1	Certification of Principal Executive Officer pursuant to 18 U.S.C. Sec. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (furnished herewith).
32.2	Certification of Principal Financial Officer pursuant to 18 U.S.C. Sec. 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (furnished herewith).
97	CoStar Group, Inc. Clawback Policy, effective September 13, 2023 (filed herewith).
101.INS	The following financial statements from the Company’s Annual Report on Form 10-K for the year ended December 31, 2023, formatted in Inline XBRL: (i) Consolidated Statements of Operations; (ii) Consolidated Statements of Comprehensive Income; (iii) Consolidated Balance Sheets; (iv) Consolidated Statements of Cash Flows; and (v) Notes to Consolidated Financial Statements, tagged as blocks of text and including detailed tags.
101.SCH	Inline XBRL Taxonomy Extension Schema Document.
101.CAL	Inline XBRL Taxonomy Extension Calculation Linkbase Document.
101.DEF	Inline XBRL Taxonomy Extension Definition Linkbase Document.
101.LAB	Inline XBRL Taxonomy Extension Label Linkbase Document.
101.PRE	Inline XBRL Taxonomy Extension Presentation Linkbase Document.
104	The cover page from the Registrant's Annual Report on Form 10-K for the year ended December 31, 2023, formatted in Inline XBRL (included as Exhibit 101).

* Management Contract or Compensatory Plan or Arrangement.

55

Item 16.    Form 10-K Summary

None.

56

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	COSTAR GROUP, INC.
	By:	/s/ Andrew C. Florance
February 21, 2024		Andrew C. Florance
		President and Chief Executive Officer

KNOW ALL PERSONS BY THESE PRESENTS, that each individual whose signature appears below constitutes and appoints Andrew C. Florance and Scott T. Wheeler, and each of them individually, as their true and lawful attorneys-in-fact and agents, with full power of substitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments to this report, and to file the same, with all exhibits thereto and to all documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, herein by ratifying and confirming all that said attorneys-in-fact and agents or any of them, or his or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1934, as amended, this report has been signed by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

57

Signature	Capacity	Date
/s/ Michael R. Klein	Chairman of the Board	February 21, 2024
Michael R. Klein
/s/ Andrew C. Florance	Chief Executive Officer and	February 21, 2024
Andrew C. Florance	President and a Director
	(Principal Executive Officer)
/s/ Scott T. Wheeler	Chief Financial Officer	February 21, 2024
Scott T. Wheeler	(Principal Financial and Accounting Officer)
/s/ Angelique G. Brunner	Director	February 21, 2024
Angelique G. Brunner
/s/ Michael J. Glosserman	Director	February 21, 2024
Michael J. Glosserman
/s/ John W. Hill	Director	February 21, 2024
John W. Hill
/s/ Laura Cox Kaplan	Director	February 21, 2024
Laura Cox Kaplan
/s/ Christopher J. Nassetta	Director	February 21, 2024
Christopher J. Nassetta
/s/ Louise S. Sams	Director	February 21, 2024
Louise S. Sams
/s/ Robert W. Musslewhite	Director	February 21, 2024
Robert W. Musslewhite

58

COSTAR GROUP, INC.

INDEX TO CONSOLIDATED FINANCIAL STATEMENTS

Reports of Independent Registered Public Accounting Firm (PCAOB ID Number 42)	F-2
Consolidated Statements of Operations	F-6
Consolidated Statements of Comprehensive Income	F-7
Consolidated Balance Sheets	F-8
Consolidated Statements of Changes in Stockholders’ Equity	F-9
Consolidated Statements of Cash Flows	F-10
Notes to Consolidated Financial Statements	F-12

F-1

Report of Independent Registered Public Accounting Firm

The Board of Directors and Stockholders of CoStar Group, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of CoStar Group, Inc. (the Company) as of December 31, 2023 and 2022, the related consolidated statements of operations, comprehensive income, changes in stockholders’ equity, and cash flows for each of the three years in the period ended December 31, 2023, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2023, in conformity with U.S. generally accepted accounting principles.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control-Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework), and our report dated February 21, 2024 expressed an unqualified opinion thereon.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective or complex judgments. The communication of the critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

F-2

	Highly Automated Revenue Systems related to Subscription Revenue
Description of the Matter	As described in Note 2 to the consolidated financial statements, the Company derives revenues primarily by (i) providing access to its proprietary database of commercial real estate information and (ii) providing online marketplaces for professional property management companies, property owners, real estate agents and brokers and landlords, in each case, typically through a fixed fee for its subscription-based services. Revenues from subscription-based contracts are approximately 95% of total revenues for the current year and are recognized on a straight-line basis over the term of the agreement. The Company’s revenue recognition process involves several applications responsible for the initiation, processing, and recording of transactions. These applications interface with the Company’s enterprise resource planning system through automated and manual journal entries to accurately reflect revenue.
	The process to calculate, aggregate, and record revenue relies on multiple internally developed and external software programs and systems and involves interfacing significant volumes of data across the systems. Auditing the Company's accounting for revenue from subscription-based contracts was challenging and complex due to the high volume of individually-low-monetary-value transactions, dependency on the effective design and operation of multiple applications, some of which are specifically designed for the Company's business, and the use of multiple data sources in the revenue recognition process. Given the complexity of the information technology (IT) environment, the required involvement of professionals with expertise in IT to identify, test, and evaluate the revenue data flows, systems, and automated controls, we considered the audit of the Company’s subscription revenue-generating transactions to be a critical audit matter.
How We Addressed the Matter in Our Audit	We performed procedures related to the Company’s internal controls that included, among others, obtaining an understanding, evaluating the design, and testing the operating effectiveness of internal controls over the Company’s accounting for subscription revenue. We tested the controls over the initiation and billing of new and recurring subscriptions, the provisioning of customers, and the Company’s cash to billings reconciliation process. We tested the controls related to the key application interfaces between the provisioning, billing, and accounting systems and tested IT general controls related to access to the relevant applications and data, and changes made to the relevant systems, configurations and interfaces.
	We performed substantive audit procedures that included, among others, testing the Company’s accounting for revenue from contracts with customers, by testing, on a sample basis, the completeness and accuracy of the underlying data within the Company’s billing system. We performed data analytics by extracting data from the general ledger to evaluate the completeness and accuracy of recorded revenue and deferred revenue amounts, tracing a sample of sales transactions to source data, and testing a sample of cash to billings reconciliations.

/s/ Ernst & Young LLP

We have served as the Company’s auditor since 1994.

Tysons, Virginia

February 21, 2024

F-3

Report of Independent Registered Public Accounting Firm

The Board of Directors and Stockholders of CoStar Group, Inc.

Opinion on Internal Control over Financial Reporting

We have audited CoStar Group, Inc.’s internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework) (the COSO criteria). In our opinion, CoStar Group, Inc. (the Company) maintained, in all material respects, effective internal control over financial reporting as of December 31, 2023, based on the COSO criteria.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the consolidated balance sheets of CoStar Group, Inc. as of December 31, 2023 and 2022, the related consolidated statements of operations, comprehensive income, changes in stockholders' equity and cash flows for each of the three years in the period ended December 31, 2023 and the related notes of CoStar Group, Inc. and our report dated February 21, 2024 expressed an unqualified opinion thereon.

As indicated in the accompanying Management’s Report on Internal Control over Financial Reporting, management’s assessment of and conclusion on the effectiveness of internal control over financial reporting did not include the internal controls of OnTheMarket Plc., which is included in the 2023 consolidated financial statements of the Company and constituted less than 1% and 1% of total and net assets, respectively, as of December 31, 2023, and less than 1% and less than 1% of revenues and net income, respectively, for the year then ended. Our audit of internal control over financial reporting of the Company also did not include an evaluation of the internal control over financial reporting of OnTheMarket Plc.

Basis for Opinion

The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting included in the accompanying Management’s Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects.

Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

Definition and Limitations of Internal Control Over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

/s/ Ernst & Young LLP

F-4

Tysons, Virginia

February 21, 2024

F-5

COSTAR GROUP, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS

(in millions, except per share data)

	Year Ended December 31,
	2023		2022		2021
Revenues	$	2,455.0	$	2,182.4	$	1,944.1
Cost of revenues	491.5		414.0		357.2
Gross profit	1,963.5		1,768.4		1,586.9
Operating expenses:
Selling and marketing (excluding customer base amortization)	989.9		684.2		622.0
Software development	267.6		220.9		201.0
General and administrative	381.5		338.7		256.8
Customer base amortization	42.2		73.6		74.8
	1,681.2		1,317.4		1,154.6
Income from operations	282.3		451.0		432.3
Interest income (expense), net	213.6		32.1		(31.6)
Other income, net	5.4		3.4		3.3
Income before income taxes	501.3		486.5		404.0
Income tax expense	126.6		117.0		111.4
Net income	$	374.7	$	369.5	$	292.6
Net income per share — basic	$	0.92	$	0.93	$	0.75
Net income per share — diluted	$	0.92	$	0.93	$	0.74
Weighted-average outstanding shares — basic	405.3		396.3		392.2
Weighted-average outstanding shares — diluted	406.9		397.8		394.2

See accompanying notes.

F-6

COSTAR GROUP, INC.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(in millions)

	Year Ended December 31,
	2023		2022		2021
Net income	$	374.7	$	369.5	$	292.6
Other comprehensive income (loss), net of tax
Foreign currency translation adjustment	11.5		(23.3)		(4.9)
Total other comprehensive income (loss)	11.5		(23.3)		(4.9)
Total comprehensive income	$	386.2	$	346.2	$	287.7

See accompanying notes.

F-7

COSTAR GROUP, INC.

CONSOLIDATED BALANCE SHEETS

(in millions, except per share data)

	December 31,
	2023		2022
ASSETS
Current assets:
Cash and cash equivalents	$	5,215.9	$	4,968.0
Accounts receivable	213.2		166.1
Less: Allowance for credit losses	(23.2)		(12.2)
Accounts receivable, net	190.0		153.9
Prepaid expenses and other current assets	70.2		64.0
Total current assets	5,476.1		5,185.9
Deferred income taxes, net	4.3		9.7
Property and equipment, net	472.2		321.3
Lease right-of-use assets	79.8		80.4
Goodwill	2,386.2		2,314.8
Intangible assets, net	313.7		329.3
Deferred commission costs, net	167.7		142.5
Deposits and other assets	17.7		16.6
Income tax receivable	2.0		2.0
Total assets	$	8,919.7	$	8,402.5
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:
Accounts payable	$	23.1	$	28.6
Accrued wages and commissions	117.8		105.0
Accrued expenses	163.0		89.1
Income taxes payable	7.7		10.4
Lease liabilities	40.0		36.0
Deferred revenue	104.2		103.6
Total current liabilities	455.8		372.7
Long-term debt, net	990.5		989.2
Deferred income taxes, net	36.7		76.2
Income taxes payable	18.2		14.0
Lease and other long-term liabilities	79.9		80.4
Total liabilities	1,581.1		1,532.5
Stockholders’ equity:
Preferred stock, $0.01 par value; 2 million shares authorized; zero outstanding	—		—
Common stock, $0.01 par value; 1.2 billion shares authorized; 408.1 million and 406.7 million issued and outstanding as of December 31, 2023 and 2022, respectively	4.1		4.1
Additional paid-in capital	5,147.8		5,065.4
Accumulated other comprehensive loss	(17.6)		(29.1)
Retained earnings	2,204.3		1,829.6
Total stockholders’ equity	7,338.6		6,870.0
Total liabilities and stockholders’ equity	$	8,919.7	$	8,402.5

 See accompanying notes.

F-8

COSTAR GROUP, INC.

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY

(in millions)

	Common Stock			Additional Paid-In Capital		Accumulated Other Comprehensive Loss		Retained Earnings		Total Stockholders’ Equity
	Shares	Amount
Balance at January 1, 2021	394.3	$	3.9	$	4,204.7	$	(0.9)	$	1,167.5	$	5,375.2
Net income	—	—		—		—		292.6		292.6
Other comprehensive loss	—	—		—		(4.9)		—		(4.9)
Exercise of stock options	0.2	—		6.3		—		—		6.3
Restricted stock issued	0.9	—		—		—		—		—
Restricted stock grants surrendered	(0.6)	—		(33.3)		—		—		(33.3)
Stock-based compensation expense	—	—		62.6		—		—		62.6
Employee stock purchase plan	0.2	—		13.0		—		—		13.0
Balance at December 31, 2021	395.0	3.9		4,253.3		(5.8)		1,460.1		5,711.5
Net income	—	—		—		—		369.5		369.5
Other comprehensive loss	—	—		—		(23.3)		—		(23.3)
Restricted stock issued	1.5	0.1		—		—		—		0.1
Restricted stock grants surrendered	(0.7)	—		(23.1)		—		—		(23.1)
Stock-based compensation expense	—	—		74.6		—		—		74.6
Employee stock purchase plan	0.2	—		15.0		—		—		15.0
Stock issued for equity offerings, net of transaction costs	10.7	0.1		745.6		—		—		745.7
Balance at December 31, 2022	406.7	4.1		5,065.4		(29.1)		1,829.6		6,870.0
Net income	—	—		—		—		374.7		374.7
Other comprehensive income	—	—		—		11.5		—		11.5
Exercise of stock options	0.4	—		7.5		—		—		7.5
Restricted stock issued	1.4	—		—		—		—		—
Restricted stock grants surrendered	(0.7)	—		(23.2)		—		—		(23.2)
Stock-based compensation expense	—	—		83.6		—		—		83.6
Management stock purchase plan	0.1	—		(3.2)		—		—		(3.2)
Employee stock purchase plan	0.2	—		17.7		—		—		17.7
Balance at December 31, 2023	408.1	$	4.1	$	5,147.8	$	(17.6)	$	2,204.3	$	7,338.6

See accompanying notes.

F-9

COSTAR GROUP, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

(in millions)

	Year Ended December 31,
	2023		2022		2021
Operating activities:
Net income	$	374.7	$	369.5	$	292.6
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	107.5		137.9		139.6
Amortization of deferred commissions costs	95.2		76.1		63.4
Amortization of Senior Notes discount and issuance costs	2.4		2.4		2.3
Non-cash lease expense	30.0		38.5		28.5
Stock-based compensation expense	85.0		75.2		63.7
Deferred income taxes, net	(37.2)		(31.2)		24.2
Credit loss expense	35.0		18.3		10.9
Other operating activities, net	(3.2)		(2.4)		(0.7)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(66.6)		(46.4)		(29.6)
Prepaid expenses and other current assets	(16.2)		(17.9)		(14.9)
Deferred commissions	(120.2)		(116.8)		(72.0)
Accounts payable and other liabilities	33.9		23.2		(30.2)
Lease liabilities	(39.2)		(37.4)		(30.9)
Income taxes payable, net	10.7		(19.3)		5.9
Deferred revenue	(1.3)		6.8		17.4
Other assets	(1.0)		2.2		(0.5)
Net cash provided by operating activities	489.5		478.7		469.7
Investing activities:
Proceeds from sale and settlement of investments	3.8		0.9		—
Proceeds from sale of property and equipment and other assets	—		30.1		0.6
Purchase and construction of Richmond assets	(117.5)		(35.2)		(123.7)
Purchases of property and equipment and other assets	(25.3)		(58.6)		(65.2)
Cash paid for acquisitions, net of cash acquired	(99.6)		(6.3)		(193.0)
Net cash used in investing activities	(238.6)		(69.1)		(381.3)
Financing activities:
Payments of long-term debt assumed in acquisition	—		(2.2)		—
Repurchase of restricted stock to satisfy tax withholding obligations	(26.4)		(23.0)		(33.3)
Proceeds from equity offering, net of transaction costs	—		745.7		—
Proceeds from exercise of stock options and employee stock purchase plan	23.4		13.5		18.0
Other financing activities	(0.7)		—		(0.4)
Net cash (used in) provided by financing activities	(3.7)		734.0		(15.7)
Effect of foreign currency exchange rates on cash and cash equivalents	0.7		(2.7)		(1.5)
Net increase in cash and cash equivalents	247.9		1,140.9		71.2
Cash and cash equivalents at beginning of year	4,968.0		3,827.1		3,755.9
Cash and cash equivalents at end of year	$	5,215.9	$	4,968.0	$	3,827.1

F-10

COSTAR GROUP, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

(in millions)

	Year Ended December 31,
	2023		2022		2021
Supplemental cash flow disclosures:
Interest paid	$	30.7	$	29.9	$	31.5
Income taxes paid	$	163.2	$	169.2	$	82.1
Supplemental non-cash investing and financing activities:
Consideration owed for acquisitions	$	7.6	$	—	$	0.1
Accrued capital expenditures and non-cash landlord incentives	$	28.9	$	14.7	$	2.1

See accompanying notes.

F-11

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1.ORGANIZATION

CoStar Group (the “Company”) provides information, analytics, online marketplaces and auction services to the commercial real estate and related business community through its comprehensive, proprietary database of commercial real estate information and related tools. The Company provides online marketplaces for commercial real estate, apartment rentals, residential real estate, land for sale and businesses for sale, and its services are typically distributed to its clients under subscription-based agreements that typically renew automatically, a majority of which have a term of at least one year. The Company operates within two operating segments, North America, which includes the U.S. and Canada, and International, which primarily includes Europe, Asia-Pacific and Latin America.

The Company acquired Homes.com, BureauxLocaux, Business Immo, and OnTheMarket in May 2021, October 2021, April 2022 and December 2023, respectively. Through our Homes.com Acquisition and OnTheMarket Acquisition, we also offer online platforms that manage workflow and marketing for residential real estate agents and brokers and provide portals for homebuyers to view residential property listings. See Note 5 for further discussion of these acquisitions.

2.SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Accounting policies are consistent for each operating segment.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to revenue recognition, allowance for credit losses, the useful lives and recoverability of long-lived and intangible assets, goodwill, income taxes, accounting for business combinations, stock-based compensation, estimating the Company's incremental borrowing rate for its leases, and contingencies, among others. The Company bases these estimates on historical and anticipated results, trends and various other assumptions that it believes are reasonable, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenues and expenses. Actual results could differ from these estimates.

Revenue Recognition

The Company derives revenues primarily by (i) providing access to its proprietary database of commercial real estate information and (ii) providing online marketplaces for professional property management companies, property owners, real estate agents and brokers and landlords, in each case, typically through a fixed monthly fee for its subscription-based services. Other subscription-based services include (i) real estate and lease management solutions to commercial customers, real estate investors and lenders, (ii) access to applications to manage workflow and advertising and marketing services for residential real estate agents through its Homes.com Network and the acquisition of OnTheMarket, (iii) benchmarking and analytics for the hospitality industry and (iv) market research, portfolio and debt analysis, management and reporting capabilities.

Subscription contract rates are generally based on the number of sites, number of users, organization size, the client’s business focus, geography, the number of properties reported on or analyzed, the number and types of services to which a client subscribes, the number of properties a client advertises and the prominence and placement of a client's advertised properties in the search results. The Company’s subscription-based license agreements typically renew automatically, and a majority have a term of at least one year. Revenue from our subscription-based contracts was approximately 95%, 93% and 93% of total revenue for the years ended December 31, 2023, 2022 and 2021, respectively.

The Company also derives revenues from transaction-based services including: (i) an online auction platform for commercial real estate through Ten-X, (ii) providing online tenant applications, including background and credit checks, and rental payment processing and (iii) ancillary products and services that are sold on an ad hoc basis.

The Company analyzes contracts to determine the appropriate revenue recognition using the following steps: (i) identification of contracts with customers, (ii) identification of distinct performance obligations in the contract, (iii)

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COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

determination of contract transaction price, (iv) allocation of contract transaction price to the performance obligations and (v) determination of revenue recognition based on timing of satisfaction of the performance obligations.

The Company recognizes revenues upon the satisfaction of its performance obligation(s) (upon transfer of control of promised services to its customers) in an amount that reflects the consideration to which it expects to be entitled to in exchange for those services. Revenues from subscription-based services are recognized on a straight-line basis over the term of the agreement. Revenues from transaction-based services are recognized when the promised product or services are delivered, which, in the case of Ten-X auctions, is at the time of a successful closing for the sale of the property.

In limited circumstances, the Company's contracts with customers include promises to transfer multiple services, such as contracts for its subscription-based services and professional services. For these contracts, the Company accounts for individual performance obligations separately if they are distinct, which involves the determination of the standalone selling price for each distinct performance obligation.

Deferred revenue results from amounts billed in advance to customers or cash received from customers in advance of the Company's fulfillment of its performance obligation(s) and is recognized as those obligations are satisfied.

Contract assets represent a conditional right to consideration for satisfied performance obligations that become a receivable when the conditions are satisfied. Contract assets are generated when contractual billing schedules differ from revenue recognition timing.

Certain sales commissions are considered incremental and recoverable costs of obtaining a contract with a customer. Sales commissions incurred for obtaining new contracts are deferred and then amortized as selling and marketing expenses on a straight-line basis over a period of benefit that the Company has determined to be three years. The three-year amortization period was determined based on several factors, including the nature of the technology and proprietary data underlying the services being purchased, customer contract renewal rates and industry competition. Sales commissions that do not represent incremental costs of obtaining a contract, or that would otherwise be amortized over a period of one year or less, are not subject to capitalization.

See Note 3 for further discussion of the Company's revenue recognition.

Cost of Revenues

Cost of revenues principally consists of salaries, benefits, bonuses, stock-based compensation expenses and other indirect costs for the Company's researchers who collect and analyze the real estate data that is the basis for the Company's information, analytics and online marketplaces and for employees that support these products. Additionally, cost of revenues includes the cost of data from third-party data sources, product hosting costs, and costs related to advertising purchased on behalf of customers, credit card and other transaction fees relating to processing customer transactions, which are expensed as incurred, and the amortization of acquired trade names, technology and certain other intangible assets.

Foreign Currency Translation

The Company’s reporting currency is the U.S. dollar. The functional currency for the majority of its operations is the local currency, with the exception of certain international locations for which the functional currency is the British Pound. Assets and liabilities denominated in a foreign currency are translated into U.S. dollars using the exchange rates in effect as of the balance sheet date. Gains and losses resulting from translation are included in accumulated other comprehensive loss. Currency gains and losses on the translation of intercompany loans made to foreign subsidiaries that are of a long-term investment nature are also included in accumulated other comprehensive loss. Gains and losses resulting from transactions denominated in a currency other than the functional currency of the entity are included in other income, net in the consolidated statements of operations using the average exchange rates in effect during the period. The Company recognized net foreign currency gains of $3.0 million, $1.4 million, and a loss of $0.3 million for the years ended December 31, 2023, 2022 and 2021, respectively, which are included in other income, net on the consolidated statements of operations.

Accumulated Other Comprehensive Loss

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COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The components of accumulated other comprehensive loss, net of tax, were as follows (in millions):

	As of December 31,
	2023		2022
Foreign currency translation loss	$	(17.6)	$	(29.1)
Total accumulated other comprehensive loss	$	(17.6)	$	(29.1)

There were no amounts reclassified out of accumulated other comprehensive loss to the consolidated statements of operations for both the years ended December 31, 2023 and 2022.

Advertising Costs

The Company expenses advertising costs as incurred. Advertising costs include digital marketing, television, radio, print and other media advertising. Advertising costs were $549.6 million, $305.7 million and $312.0 million for the years ended December 31, 2023, 2022 and 2021, respectively.

Income Taxes

Deferred income taxes result from temporary differences between the tax basis of assets and liabilities and the basis reported in the Company’s consolidated financial statements. Deferred tax liabilities and assets are determined based on the difference between the financial statement and the tax basis of assets and liabilities using enacted rates in effect during the year in which the Company expects differences to reverse. Valuation allowances are provided against assets, including net operating losses, if the Company determines it is more likely than not that some portion or all of an asset may not be realized. Interest and penalties related to income tax matters are recognized in income tax expense.

The Company has elected to record the GILTI under the current-period cost method.

See Note 12 for further discussion of income taxes.

Net Income Per Share

Net income per share is computed by dividing net income by the weighted-average number of common shares outstanding during the period on a basic and diluted basis. The Company's potentially dilutive securities include outstanding stock options, unvested stock-based awards, which include restricted stock awards that vest over a specific service period, restricted stock awards with a performance and market condition, restricted stock units and Matching RSUs awarded under the MSPP. Shares underlying unvested restricted stock awards that vest based on a performance and market condition that have not been achieved as of the end of the period are not included in the computation of basic or diluted earnings per share. Diluted net income per share considers the impact of potentially dilutive securities except when the inclusion of the potentially dilutive securities would have an anti-dilutive effect.

See Note 16 for further discussion of the Company's calculation of net income per share.

Stock-Based Compensation

Equity instruments issued in exchange for services performed by officers, employees and directors of the Company are accounted for using a fair-value based method and the fair value of such equity instruments is recognized as expense in the consolidated statements of operations.

For stock-based awards that vest over a specific service period, compensation expense is measured based on the fair value of the awards at the grant date and is recognized on a straight-line basis over the service period of the awards, net of an estimated forfeiture rate. For equity instruments that vest based on achievement of both a performance and market condition, stock-based compensation expense is recognized over the service period of the awards based on the expected achievement of the related performance conditions at the end of each reporting period. If the Company's initial estimates of the achievement of the performance conditions change, the related stock-based compensation expense may fluctuate from period to period based on those estimates. If the performance conditions are not met, no stock-based compensation expense will be recognized and any previously recognized stock-based compensation expense will be reversed. For awards with both a performance and a market condition, the Company estimates the fair value of each equity instrument granted on the date of grant using a Monte-Carlo simulation model. This pricing model uses multiple simulations to evaluate the probability of achieving the market condition to calculate the fair value of the awards which includes the recent market price and volatility of the Company's shares. When

F-14

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

determining the grant date fair value of all stock-based awards, the Company considers whether it is in possession of any material, non-public information that upon its release would have a material effect on its share price, and if so, whether the observable share price or expected volatility assumptions used in determining the fair value of the awards should be adjusted.

Stock-based compensation expense for stock options, restricted stock awards and restricted stock units issued under equity incentive plans, stock purchases under the ESPP, DSUs and Matching RSUs awarded under the MSPP included in the Company’s consolidated statements of operations were as follows (in millions):

	Year Ended December 31,
	2023		2022			2021
Cost of revenues	$	14.3	$	12.6		$	11.2
Selling and marketing (excluding customer base amortization)	9.1		7.8		7.8	6.3
Software development	17.5		13.0			12.5
General and administrative	44.1		41.8			33.7
Total stock-based compensation expense	$	85.0	$	75.2		$	63.7

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Cash and cash equivalents were $5.2 billion and $5.0 billion as of December 31, 2023 and 2022, respectively. The Company had no restricted cash as of December 31, 2023 and 2022.

Concentration of Credit Risk and Financial Instruments

The Company’s customer base creates a lack of dependence on any individual customer that mitigates the risk of nonpayment of the Company’s accounts receivable. No single customer accounted for more than 5% of the Company’s revenues for each of the years ended December 31, 2023, 2022 and 2021. The carrying amount of the accounts receivable approximates the net realizable value.

The Company holds cash at major financial institutions that often exceed Federal Deposit Insurance Corporation-insured limits. The Company manages its credit risk associated with cash concentrations by diversifying cash holdings across AAA rated Government and Treasury Money Market Funds and multiple high quality financial institutions, and by periodically evaluating the credit quality of the primary financial institutions holding such deposits. The carrying value of cash approximates fair value. Historically, the Company has not experienced any losses due to such cash concentrations.

Allowance for Credit Losses

The Company maintains an allowance for credit losses to cover its current expected credit losses on its trade receivables and contract assets arising from the failure of customers to make contractual payments. The Company estimates credit losses expected over the life of its trade receivables and contract assets based on historical information combined with current conditions that may affect a customer’s ability to pay and reasonable and supportable forecasts. While the Company uses various credit quality metrics, it primarily monitors collectability by reviewing the duration of collection pursuits on its delinquent trade receivables and historical write-off trends. Based on the Company’s experience, the customer's delinquency status, which is analyzed periodically, is the strongest indicator of the credit quality of the underlying trade receivables. The Company’s policy is to write-off trade receivables when they are deemed uncollectible. A majority of the Company's trade receivables are less than 365 days outstanding.

Under the CECL impairment model, the Company develops and documents its allowance for credit losses on its trade receivables based on five portfolio segments. The determination of portfolio segments is based primarily on the qualitative consideration of the nature of the Company’s business operations and the characteristics of the underlying trade receivables, as follows:

•CoStar Portfolio Segment - The CoStar portfolio segment consists of two classes of trade receivables based on geographical location: North America and International.

F-15

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

•Information Services Portfolio Segment - The Information Services portfolio segment consists of four classes of trade receivables: CoStar Real Estate Manager; Information Services, North America; STR, North America; and STR, International.

•Multifamily Portfolio Segment - The Multifamily portfolio segment consists of one class of trade receivables.

•LoopNet Portfolio Segment - The LoopNet portfolio segment consists of one class of trade receivables.

•Other Marketplaces Portfolio Segment - The Other Marketplaces portfolio segment consists of two classes of trade receivables: Ten-X and other marketplaces.

The majority of Residential revenue is e-commerce based and does not result in accounts receivable. Residential accounts receivable and the related allowance for credit losses are not material.

See Note 4 for further discussion of the Company’s accounting for allowance for credit losses.

Leases

The determination of whether an arrangement contains a lease and the classification of a lease, if applicable, is made at the commencement of the arrangement, at which time the Company also measures and recognizes an ROU asset, representing the Company’s right to use the underlying asset, and a lease liability, representing the Company’s obligation to make lease payments under the terms of the arrangement. For the purposes of recognizing ROU assets and lease liabilities associated with the Company’s leases, the Company has elected the practical expedient to not recognize a ROU asset or lease liability for short-term leases, which are leases with a term of 12 months or less. The lease term is defined as the noncancelable portion of the lease term, plus any periods covered by an option to extend the lease if it is reasonably certain that the option will be exercised.

In determining the amount of lease payments used in measuring ROU assets and lease liabilities, the Company has elected the practical expedient not to separate non-lease components from lease components for all classes of underlying assets. Consideration deemed part of the lease payments used to measure ROU assets and lease liabilities generally includes fixed payments and variable payments based on either an index or a rate, offset by lease incentives. Upon commencement, the initial ROU asset also includes any lease prepayments. ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The rates implicit within the Company's leases are generally not determinable. Therefore, the Company's incremental borrowing rate is used to determine the present value of lease payments. The determination of the Company’s incremental borrowing rate requires judgment and is determined at lease commencement and is subsequently reassessed upon a modification to the lease arrangement.

Lease costs related to the Company's operating leases are generally recognized as a single ratable lease cost over the lease term. ROU assets resulting from finance leases are accounted for as property and equipment, net.

See Note 7 for further discussion of the Company’s accounting for leases.

Property and Equipment, Net

Property and equipment are stated at cost, net of accumulated depreciation and amortization. All repairs and maintenance costs are expensed as incurred. Costs related to acquisition of additional aircraft components or the replacement of existing aircraft components are capitalized and depreciated over the estimated useful life of the aircraft or the added or replaced component, whichever is less. Depreciation and amortization are calculated on a straight-line basis over the following estimated useful lives of the assets:

Buildings	Twenty to thirty-nine years
Land	Indefinite
Aircrafts	Ten to twenty years
Furniture and office equipment	Five to ten years
Vehicles	Four to five years
Computer hardware and software	Three to five years
Leasehold improvements	Shorter of lease terms or useful life

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COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Qualifying internal-use software costs incurred during the application development stage, which consist primarily of internal product development costs, are capitalized and amortized over the estimated useful life of the asset. All other costs are expensed as incurred. The Company removes fully depreciated property and equipment from the cost and accumulated depreciation amounts disclosed in the period they become fully depreciated.

In January 2021, the Company purchased an office building located in Richmond, Virginia, together with the land and assumed an existing lease for a purchase price of $131 million, inclusive of property taxes, title insurance and other transaction costs. The purchase of the Richmond building was accounted for as an asset acquisition, including an intangible asset for the assumed lease. The assumed lease terminated in the year ending December 31 2023. The net impact from the lease arrangement is recorded in other income, net on the consolidated statements of operations and was not material. The Company has broken ground on an expansion of its campus in Richmond, Virginia and acquired a small office building near the campus to facilitate employee staging while the expansion is being constructed. The capitalized spending associated with these efforts is recorded in the purchase and construction of Richmond assets line of the consolidated statements of cash flows.

Long-Lived Assets, Intangible Assets and Goodwill

Long-lived assets, such as property and equipment, and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company capitalizes interest on borrowings during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying asset and amortized over the estimated useful life of the asset. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset or asset group. If the carrying amount of an asset exceeds its estimated undiscounted future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset.

During 2022, the Company ceased using leased properties in California and Maryland as part of efforts to centralize its workforce, which resulted in an impairment charge of $9 million for lease ROU assets and property and equipment related to abandoned leases. The impairment was recorded in the general and administrative expense line of the consolidated statements of operations. The leases related to the North America segment.

Acquired technology and data, customer base assets, trade names and other intangible assets are related to the Company’s acquisitions. Acquired technology and data is amortized on a straight-line basis over periods ranging from 2 years to 7 years. Acquired intangible assets characterized as customer base assets consist of acquired customer contracts and the related customer relationships and are amortized over periods ranging from 3 years to 13 years. Acquired customer bases are amortized on an accelerated or straight-line basis depending on the expected economic benefit of the intangible asset. Acquired trade names and other intangible assets are amortized on a straight-line basis over periods ranging from 3 years to 15 years. The Company removes fully amortized intangible assets from the cost and accumulated amortization amounts disclosed.

Goodwill represents the future economic benefits arising from a business combination and is calculated as the excess of the purchase consideration paid in a business combination over the fair value of the net identifiable assets acquired. Goodwill is not amortized, but instead is assigned to each of the Company's reporting units and tested for impairment at least annually, on October 1, or more frequently if an event or other circumstance indicates that the fair value of a reporting unit may be below its carrying amount. The Company may first assess qualitative factors to evaluate whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or elect to bypass the qualitative assessment. If it is determined that it is more likely than not that the fair value of a reporting unit is less than its carrying value, or the Company elects to bypass the qualitative assessment, the Company then performs a quantitative assessment by determining the fair value of each reporting unit. The estimate of the fair value of each reporting unit is based on a projected discounted cash flow model that includes significant assumptions and estimates including the discount rate, growth rate and future financial performance. Assumptions about the discount rate are based on a weighted average cost of capital for comparable companies. Assumptions about the growth rate and future financial performance of a reporting unit are based on the Company's forecasts, business plans, economic projections and anticipated future cash flows. The fair value of each reporting unit is compared to the carrying amount of the reporting unit. If the carrying value of the reporting unit exceeds the fair value, then an impairment loss is recognized for the difference.

See Notes 5, 9 and 10 for further discussion of acquisitions, goodwill and intangible assets, respectively.

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COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Debt Issuance Costs

Costs incurred in connection with the issuance of long-term debt are deferred and amortized as interest expense over the term of the related debt using the effective interest method for term debt and on a straight-line basis for revolving debt. The Company made a policy election to classify deferred issuance costs on the revolving credit facility as a long-term asset on its consolidated balance sheets. Upon a refinancing or amendment, previously capitalized debt issuance costs are expensed and included in loss on extinguishment of debt if the Company determines that there has been a substantial modification of the related debt. If the Company determines that there has not been a substantial modification of the related debt, any previously capitalized debt issuance costs are amortized as interest expense over the term of the new debt instrument.

See Note 11 for further discussion of the Company's accounting for its outstanding debt, revolving credit facility and related issuance costs.

Business Combinations

The Company includes the results of operations of the businesses that it acquires from the date of acquisition. The Company generally allocates the purchase consideration to the tangible assets acquired and liabilities assumed and intangible assets acquired based on their estimated fair values on the date of the acquisition. The purchase price is generally determined based on the fair value of the assets transferred, liabilities assumed and equity interests issued, after considering any transactions that are separate from the business combination. The excess of the fair value of purchase consideration over the fair values of these identifiable assets and liabilities is recorded as goodwill. The Company applies significant assumptions, estimates and judgments in determining the fair value of assets acquired and liabilities assumed on the acquisition date, especially with respect to intangible assets and contingent liabilities. Significant estimates in valuing certain intangible assets include, but are not limited to, future expected cash flows from acquired customer bases, acquired technology and acquired trade names, useful lives, royalty rates and discount rates. Estimates of fair value are based on assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. Any adjustments to provisional amounts that are identified during the measurement period, not to exceed one year from the date of acquisition, are recorded in the reporting period in which the adjustment amounts are determined. Upon the conclusion of the measurement period, any subsequent adjustments are recorded to earnings.

For a given acquisition, the Company may identify certain pre-acquisition contingencies as of the acquisition date and may extend its review and evaluation of these pre-acquisition contingencies throughout the measurement period in order to obtain sufficient information to assess whether the Company includes these contingencies as a part of the fair value estimates of assets acquired and liabilities assumed and, if so, to determine their estimated amounts.

If the Company cannot reasonably determine the fair value of a pre-acquisition contingency (non-income tax related) by the end of the measurement period, which is generally the case given the nature of such matters, the Company will recognize an asset or a liability for such pre-acquisition contingency if: (i) it is probable that an asset existed or a liability had been assumed at the acquisition date and (ii) the amount of the asset or liability can be reasonably estimated. Subsequent to the measurement period, changes in the Company's estimates of such contingencies will affect earnings and could have a material effect on its results of operations and financial position.

In addition, uncertain tax positions and tax-related valuation allowances assumed in connection with a business combination are initially estimated as of the acquisition date. The Company reevaluates these items based upon facts and circumstances that existed as of the acquisition date with any adjustments to its preliminary estimates being recorded to goodwill, provided that the Company is within the measurement period. Subsequent to the measurement period, changes to these uncertain tax positions and tax-related valuation allowances will affect the Company's provision for income taxes in its consolidated statements of operations and comprehensive income and could have a material impact on its results of operations and financial position.

Transaction costs associated with business combinations are expensed as incurred, and are included in general and administrative expenses in the consolidated statements of operations.

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In 2021, the Company adopted ASU 2021-08, Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. This guidance requires contract assets and liabilities acquired or assumed in an acquisition be measured in accordance with the accounting framework for revenue from contracts with customers as if the

F-18

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Company had originated the acquired contract. This is an exception to the general requirement to measure assets acquired and liabilities assumed at their fair value on the acquisition date. The Company applied this revised guidance to all acquisitions in the year ended December 31, 2021. The application of this guidance to contract assets and contract liabilities acquired or assumed in connection with the Company's acquisitions for the year ended December 31, 2021 did not have a material impact on the Company's consolidated financial statements and related disclosures.

In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASC 848 contains optional expedients and exceptions for applying GAAP to debt, contracts, hedging relationships and other transactions affected by reference rate reform. The provisions of ASC 848 must be applied to all contracts that are accounted for under a Topic, Subtopic or Industry Subtopic for all transactions other than derivatives, which may be applied at a hedging relationship level. Originally, the guidance was effective for fiscal years beginning after January 1, 2021, including interim periods within those fiscal years. However, in response to the deferral of the cessation date for certain overnight LIBOR measures, the FASB issued ASU 2022-06 on December 21, 2022, which extends the sunset date of Topic 848 to December 31, 2024. The Company's 2020 Credit Agreement provides for a $750 million revolving credit facility and a letter of credit sublimit of $20 million, with interest rates previously benchmarked to LIBOR. The Company adopted this accounting pronouncement with the execution of the First Amendment to the 2020 Credit Agreement in May 2023. This guidance provides an optional practical expedient that allows a qualifying modification to be accounted for as a debt modification rather than be analyzed under existing guidance to determine if the modification should be accounted for as a debt extinguishment. In adopting this accounting standard, we have elected to apply this optional expedient. Adopting this accounting standard did not have a material impact on the Company's consolidated financial statements and related disclosures.

Recent Accounting Pronouncements Not Yet Adopted

In March 2022, the FASB issued ASU 2022-02, Financial Instruments-Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures. This ASU eliminates prior guidance on troubled debt restructurings for creditors that have adopted ASU 2016-13, Measurement of Credit Losses in Financial Statements, and adds enhanced disclosures for creditors with respect to loan refinancings and restructurings for borrowers experiencing financial difficulty. In addition, the ASU amends guidance on "vintage disclosures" to require the disclosure of current period gross write offs by year of origination. This guidance is effective for fiscal years beginning after December 15, 2022. The Company expects there to be no material impact on its consolidated financial statements and related disclosures from the adoption of this ASU.

In November 2023, the FASB issued ASU No. 2023-07 (Topic 280), Improvements to Reportable Segment Disclosures. The ASU primarily will require enhanced disclosures about significant segment expenses. Additionally, it requires disclosure of the title and position of the individual identified as the CODM and an explanation of how the CODM uses the reported measures of a segment’s profit or loss in assessing segment performance and deciding how to allocate resources. The ASU is effective for annual periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Adoption of the ASU should be applied retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures.

In December 2023, the FASB issued ASU No. 2023-09 (Topic 740), Improvements to Income Tax Disclosures (Topic 740). The ASU requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as an expansion of other income tax disclosures. The ASU is effective on a prospective basis for annual reporting periods beginning after December 15, 2024. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures.

F-19

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

3.    REVENUE FROM CONTRACTS WITH CUSTOMERS

Disaggregated Revenue

The Company provides information, analytics and online marketplaces to the commercial real estate industry, hospitality industry, residential industry and related professionals. Revenues by operating segment and type of service consist of the following (in millions):

	Year Ended December 31,
	2023						2022						2021
	North America		International		Total		North America		International		Total		North America		International		Total
CoStar	$	886.0	$	39.2	$	925.2	$	800.2	$	36.8	$	837.0	$	686.9	$	35.9	$	722.8
Information services	132.4		38.5		170.9		125.0		32.4		157.4		113.8		27.9		141.7
Multifamily	914.2		—		914.2		745.4		—		745.4		678.7		—		678.7
LoopNet	255.4		9.4		264.8		223.7		7.2		230.9		204.8		2.7		207.5
Residential	43.9		2.2		46.1		73.7		—		73.7		74.6		—		74.6
Other Marketplaces	133.8		—		133.8		138.0		—		138.0		118.8		—		118.8
Total revenues	$	2,365.7	$	89.3	$	2,455.0	$	2,106.0	$	76.4	$	2,182.4	$	1,877.6	$	66.5	$	1,944.1

Deferred Revenue

Deferred revenue as of December 31, 2023 and 2022 was as follows (in millions):

		December 31,
Balance	Balance Sheet Caption	2023		2022
Current portion	Deferred revenue	$	104.2	$	103.6
Non-current portion	Lease and other long-term liabilities	0.1		0.2
Total deferred revenue		$	104.3	$	103.8

Changes in deferred revenue for the period were as follows (in millions):

Balance at December 31, 2022(1)	$	103.8
Revenue recognized in the current period from the amounts in the beginning balance	(103.8)
New deferrals, net of amounts recognized in the current period	103.4
Effects of foreign currency	0.9
Balance at December 31, 2023(2)	$	104.3
__________________________

(1) This balance includes $1.8 million of net new deferrals recognized in connection with business acquisitions made in 2022. See Note 5 for further discussion of acquisitions.

(2) This balance includes $1.0 million of net new deferrals recognized in connection with business acquisitions made in 2023. See Note 5 for further discussion of acquisitions.

Contract Assets

Contract assets are generated when contractual billing schedules differ from revenue recognition timing and represent a conditional right to consideration for satisfied performance obligations that becomes a receivable when the conditions are satisfied. Contract assets as of December 31, 2023 and 2022 were as follows (in millions):

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COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

		December 31,
Balance	Balance Sheet Caption	2023		2022
Current portion	Prepaid expenses and other current assets	$	5.8	$	4.0
Non-current portion	Deposits and other assets	8.0		8.4
Total contract assets		$	13.8	$	12.4

Revenue recognized from contract assets for the years ended December 31, 2023 and 2022 were $1.4 million and $3.2 million, respectively.

Commissions

Commissions expense is included in selling and marketing expense in the Company's consolidated statements of operations. The Company determined that no deferred commissions were impaired as of both December 31, 2023 and 2022. Commissions expense activity for the years ended December 31, 2023, 2022 and 2021, was as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Commissions incurred	$	173.5	$	162.1	$	117.3
Commissions capitalized in the current period	(120.2)		(116.8)		(72.0)
Amortization of deferred commissions costs	95.2		76.1		63.4
Total commissions expense	$	148.5	$	121.4	$	108.7

See Note 2 for the Company's policy on accounting for commissions.

Unsatisfied Performance Obligations

Remaining contract consideration for which revenue had not been recognized due to unsatisfied performance obligations was $409.6 million as of December 31, 2023, which the Company expects to recognize over the next five years. This amount does not include contract consideration for contracts with a duration of one year or less.

F-21

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

4.ALLOWANCE FOR CREDIT LOSSES

The following tables detail the activity related to the allowance for credit losses for trade receivables by portfolio segment (in millions):

	Year Ended December 31, 2023
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2022	$	4.5	$	1.1	$	4.3	$	1.4	$	0.9	$	12.2
Current-period provision (release) for expected credit losses	22.1		1.4		4.9		6.0		0.6		35.0
Write-offs charged against the allowance, net of recoveries and other	(16.9)		—		(1.9)		(4.7)		(0.5)		(24.0)
Ending balance at December 31, 2023	$	9.7	$	2.5	$	7.3	$	2.7	$	1.0	$	23.2

-

	Year Ended December 31, 2022
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2021	$	5.4	$	1.8	$	3.4	$	2.0	$	0.8	$	13.4
Current-period provision (release) for expected credit losses	9.2		(0.6)		5.8		3.8		0.1		18.3
Write-offs charged against the allowance, net of recoveries and other	(10.1)		(0.1)		(4.9)		(4.4)		—		(19.5)
Ending balance at December 31, 2022	$	4.5	$	1.1	$	4.3	$	1.4	$	0.9	$	12.2

	Year Ended December 31, 2021
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2020	$	5.6	$	2.7	$	4.4	$	1.7	$	0.8	$	15.2
Current-period provision for expected credit losses	5.6		(0.4)		3.1		2.6		—		10.9
Write-offs charged against the allowance, net of recoveries and other	(5.8)		(0.5)		(4.1)		(2.3)		—		(12.7)
Ending balance at December 31, 2021	$	5.4	$	1.8	$	3.4	$	2.0	$	0.8	$	13.4

Credit loss expense is included in general and administrative expenses on the consolidated statements of operations. Credit loss expense related to contract assets was not material for the years ended December 31, 2023, 2022 and 2021. The majority of the Residential portfolio segment revenue is e-commerce based and does not result in accounts receivable.

F-22

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

5.    ACQUISITIONS

OnTheMarket

On December 12, 2023, CoStar UK acquired OnTheMarket, the operator of onthemarket.com, a U.K. residential property portal. At the time of closing, CoStar UK acquired all of the then issued ordinary share capital of OnTheMarket for cash consideration of 110 pence per share or £94.0 million ($117.9 million). OnTheMarket had certain share option contracts that had not been exercised at the time of closing for which CoStar UK has established a liability for £2.0 million ($2.6 million). This resulted in total consideration of £96.0 million ($120.4 million). Certain shares outstanding at the time of the closing resulted from contracts held by employees of OnTheMarket or its subsidiaries that required OnTheMarket to withhold income and employment taxes of £4.0 million ($5.1 million) which represented consideration payable at December 31, 2023 and were remitted in January 2024.

The following table summarized the amounts recorded for acquired assets and assumed liabilities recorded at their fair value as of the closing date of the acquisition (in millions):

	Preliminary: December 12, 2023
Cash and cash equivalents	$	18.2
Accounts receivable	2.3
Goodwill	62.8
Intangible assets	55.2
Accrued expenses	(12.7)
Accrued wages and commissions	(2.0)
Deferred income taxes, net	(3.0)
Other assets and liabilities	(0.4)
Fair value of identifiable net assets acquired	$	120.4

The net assets of OnTheMarket were recorded at their estimated fair values. In valuing the acquired assets and assumed liabilities, fair value estimates were based primarily on future expected cash flows, market rate assumptions for contractual obligations and appropriate discount rates. The purchase price allocation is preliminary, subject primarily to the Company's assessment of certain tax matters, contingencies and intangibles valuation. The estimated fair value of the customer base assets incorporated significant assumptions that had a material impact on the estimated fair value, such as discount rates, projected revenue growth rates, customer attrition rates and profit margins.

The following table summarizes the fair values (in millions) of the identifiable intangible assets acquired in the OnTheMarket Acquisition included in the Company's International operating segment, their related estimated useful lives (in years) and their respective amortization methods:

	Estimated Fair Value		Estimated Useful Life	Amortization Method
Customer base	$	42.0	8	Accelerated
Trade name	10.2		15	Straight-line
Technology	3.0		2	Straight-line
Total intangible assets	$	55.2

F-23

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Goodwill is calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. Specifically, the goodwill recorded as part of the OnTheMarket Acquisition includes, but is not limited to: (i) the expected synergies and other benefits that the Company believes will result from combining its operations with international operations and (ii) any intangible assets that do not qualify for separate recognition, such as the assembled workforce. The $62.8 million of goodwill recorded as part of the acquisition is associated with the Company's International operating segment, of which none is expected to be deductible for income tax purposes. Transaction costs associated with the OnTheMarket Acquisition were $11.0 million.

Business Immo

In April 2022, the Company acquired Business Immo, a leading commercial real estate news service provider in France, for €5.8 million ($6.3 million), net of cash acquired and the assumption of outstanding debt. As part of the acquisition, the Company recorded goodwill and intangible assets of $7.1 million and $3.9 million, respectively. The net assets of Business Immo were recorded at their estimated fair value. The Company retired the assumed debt in the second quarter of 2022. The net assets of Business Immo were recorded at their estimated fair value. The Company retired the assumed debt in the second quarter of 2022.

BureauxLocaux

In October 2021, CoStar UK acquired BureauxLocaux, a commercial real estate digital marketplace in France, for a base purchase price of €35.0 million ($40.6 million) in cash, subject to customary working capital and other post-closing adjustments which were settled in the fourth quarter of 2021. As part of the acquisition, the Company recorded goodwill and intangible assets of $27.4 million and $18.3 million, respectively, in the Company's International operating segment. The net assets of BureauxLocaux were recorded at their estimated fair value.

Homes.com

In May 2021, the Company closed the Homes.com Acquisition, in which the Company acquired all of the issued and outstanding equity interests in Homes Group for a purchase price of $150.0 million in cash, subject to customary working capital and other post-closing adjustments which resulted in total consideration of $152.2 million. Homes Group operates Homes.com, a residential marketplace hosted on the website Homes.com and mobile apps that provided real estate advertising and marketing services. In November 2022 CoStar Group integrated the operations of Homes.com and Homesnap.

The following table summarizes the amounts recorded for acquired assets and assumed liabilities recorded at their fair values as of the acquisition date (in millions):

	Final: May 24, 2021
Cash and cash equivalents	$	—
Accounts receivable	1.8
Lease right-of-use assets	0.4
Goodwill	91.9
Intangible assets	53.4
Deferred income taxes, net	7.9
Lease liabilities	(0.4)
Deferred revenue	(1.5)
Other assets and liabilities	(1.3)
Fair value of identifiable net assets acquired	$	152.2

The net assets of Homes Group were recorded at their estimated fair values. In valuing the acquired assets and assumed liabilities, fair value estimates were based primarily on future expected cash flows, market rate assumptions for contractual obligations and appropriate discount rates. The estimated fair value of the customer base assets incorporated significant assumptions that had a material impact on the estimated fair value, such as discount rates, projected revenue growth rates, customer attrition rates and profit margins.

F-24

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The following table summarizes the fair values (in millions) of the identifiable intangible assets acquired in the Homes.com Acquisition included in the Company's North America operating segment, their related estimated useful lives (in years) and their respective amortization methods:

	Estimated Fair Value		Estimated Useful Life	Amortization Method
Customer base	$	32.0	8	Accelerated
Trade name	21.0		15	Straight-line
Technology	0.4		2	Straight-line
Total intangible assets	$	53.4

Goodwill is calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. Specifically, the goodwill recorded as part of the Homes.com Acquisition includes but is not limited to: (i) the expected synergies and other benefits that the Company believes will result from combining its operations with Homes.com operations and (ii) any intangible assets that do not qualify for separate recognition, such as the assembled workforce. The $91.9 million of goodwill recorded as part of the acquisition is associated with the Company's North America operating segment, of which $20.0 million is expected to be deductible for income tax purposes.

Transaction costs associated with the Homes.com Acquisition were not material. The Company paid $5.0 million into a cash escrow account for stay bonuses for certain Homes.com employees and recognized compensation expense for the stay bonus over the six-month post-combination period. Upon acquisition, the Company assessed the probability it would be required to pay certain state tax liabilities and recorded an accrual of $6.6 million determined in accordance with the provisions of ASC 450, Contingencies, as the fair value was not determinable. Landmark has agreed to indemnify the Company for tax liabilities related to periods prior to the acquisition and an indemnification asset was established for $6.6 million in the purchase price allocation.

Pro Forma Financial Information (unaudited)

The unaudited pro forma financial information presented below reflects the consolidated results of operations of the Company assuming the OnTheMarket Acquisition had taken place on January 1, 2022 and was as follows (in millions, except per share data):

	Year Ended December 31,
	2023		2022
Revenue	$	2,494.0	$	2,224.3
Net income	$	371.9	$	361.9
Net income per share - basic	$	0.91	$	0.91
Net income per share - diluted	$	0.91	$	0.91

The impact of the OnTheMarket Acquisition on the Company's revenue and net income in the consolidated statements of operations from December 12, 2023 through December 31, 2023 was not material.

F-25

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The unaudited pro forma financial information presented below reflects the consolidated results of operations of the Company assuming the Homes.com Acquisition had taken place on January 1, 2020 and was as follows (in millions, except per share data):

	Year Ended December 31,
	2021
Revenue	$	1,962.1
Net income	$	286.7
Net income per share - basic	$	0.74
Net income per share - diluted	$	0.73

The unaudited pro forma financial information for all periods presented includes amortization charges from acquired intangible assets, retention compensation, as referenced above, and the related tax effects, along with certain other accounting effects, but excludes the impacts of any expected operational synergies. The unaudited pro forma financial information, as presented above, is for informational purposes only and is not necessarily indicative of the results of operations that would have been achieved if the acquisitions had not taken on place on the dates listed above.

The impact of the Homes.com Acquisition on the Company's revenues and net income in the consolidated statements of operations from May 24, 2021 through December 31, 2021 was an increase of $13.6 million and a decrease of $23.5 million, respectively.

The pro forma financial information of the BureauxLocaux Acquisition and Business Immo Acquisition was not material.

6.    INVESTMENTS AND FAIR VALUE MEASUREMENTS

Fair value is defined as the price that would be received in the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. There is a three-tier fair value hierarchy, which categorizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs for which little or no market data exists, therefore requiring an entity to develop its own assumptions.

The Company's financial assets comprise Level 1 cash equivalents with original maturities of three months or less in the amount of $5.1 billion and $4.8 billion as of December 31, 2023 and 2022, respectively. The Company had no Level 2 or Level 3 financial assets measured at fair value.

The Company holds other financial instruments, including cash deposits, accounts receivable, accounts payable, accrued expenses and Senior Notes. The carrying value for such financial instruments, other than the Senior Notes, each approximated their fair values as of December 31, 2023 and 2022. The estimated fair value of the Company's outstanding Senior Notes using quoted prices from the over-the-counter markets, considered Level 2 inputs, was $0.9 billion and $0.8 billion as of December 31, 2023 and 2022, respectively.

F-26

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

7.    LEASES

The Company has operating and finance leases for its office facilities, data centers, and vehicles. The Company's leases have remaining terms up to eight years. The leases contain various renewal and termination options. The period that is subject to an option to extend the lease is included in the lease term if it is reasonably certain that the option will be exercised. The period that is subject to an option to terminate the lease is included if it is reasonably certain that the option will not be exercised.

Lease costs related to the Company's operating and finance leases included in the consolidated statements of operations were as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Operating lease costs:
Cost of revenues	$	10.0	$	8.4	$	10.1
Software development	6.3		7.2		6.9
Selling and marketing (excluding customer base amortization)	15.4		12.6		11.9
General and administrative	4.0		5.4		5.9
Total operating lease costs	35.7		33.6		34.8
Finance lease costs:
Amortization of ROU assets	0.8		—		—
Interest on lease liabilities	0.2		—		—
Total finance lease costs	1.0		—		—
Total lease costs	$	36.7	$	33.6	$	34.8

Finance lease costs primarily relate to vehicles used by the Company's research teams, and the amortization of the ROU assets are recorded to cost of revenue in the consolidated statements of operations. The impact of lease costs related to short-term leases was not material for the years ended December 31, 2023, 2022 and 2021.

F-27

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Supplemental balance sheet information related to operating leases was as follows ($ in millions):

		Year Ended December 31,
Balance	Balance Sheet Location	2023			2022
Operating lease liabilities		$	109.9		$	118.3
Less: imputed interest		(7.0)			(6.2)
Present value of lease liabilities		102.9			112.1
Less: current portion of lease liabilities	Lease liabilities	36.9			36.0
Long-term lease liabilities	Lease and other long-term liabilities	$	66.0		$	76.1
Weighted-average remaining lease term in years		3.9			3.6
Weighted-average discount rate		3.6		%	3.1		%
ROU Assets	Lease right-of-use assets	$	79.8		$	80.4
Finance lease liabilities		$	14.6		$	—
Less: imputed interest		(1.6)			—
Present value of lease liabilities		13.0			—
Less: current portion of lease liabilities	Lease liabilities	3.1			—
Long-term lease liabilities	Lease and other long-term liabilities	$	9.9		$	—
Weighted-average remaining lease term in years		3.8			0
Weighted-average discount rate		7.8		%	—		%
ROU Assets	Property and equipment, net	$	10.8		$	—

Supplemental cash flow information related to leases was as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used in operating leases	$	44.9	$	41.6	$	37.3
Operating cash flows used in finance leases	$	0.2	$	—	$	—
Financing cash flows used in finance leases	$	0.7	$	—	$	—
ROU assets obtained in exchange for lease new obligations:
Operating leases	$	29.1	$	20.0	$	34.2
Finance leases	$	13.6	$	—	$	—

F-28

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

8.    PROPERTY AND EQUIPMENT

Property and equipment consists of the following (in millions):

	December 31,
	2023		2022
Leasehold improvements	$	87.8	$	108.9
Furniture, office equipment and vehicles	73.4		52.6
Computer hardware and software	56.3		43.8
Aircrafts	44.2		44.2
Land	52.2		52.2
Buildings	263.8		105.1
Property and equipment, gross	577.7		406.8
Accumulated depreciation and amortization	(105.5)		(85.5)
Property and equipment, net	$	472.2	$	321.3

Costs capitalized in connection with the expansion of our Richmond, Virginia campus were included in Buildings in the above table as of December 31, 2023. Depreciation expense for property and equipment was approximately $33.8 million, $29.1 million and $29.0 million, for the years ended December 31, 2023, 2022 and 2021, respectively. For the years ended December 31, 2023 and 2022, the Company removed $14.1 million and $27.6 million, respectively, of property and equipment that was fully depreciated from property and equipment, gross and accumulated depreciation and amortization, which had no net impact on the Company's financial results.

In August 2022, the Company entered into an agreement to sell an aircraft subject to customary condition and inspection terms. The sale of the aircraft closed in October 2022 for cash consideration of $24.9 million. The Company recorded a gain on the sale of the aircraft of $3.3 million, which was recorded to general and administrative expenses in the consolidated statements of operations. The aircraft related to the North America segment.

9.    GOODWILL

The changes in the carrying amount of goodwill by operating segment consist of the following (in millions):

	North America		International		Total
Goodwill, December 31, 2021	$	2,145.8	$	175.2	$	2,321.0
Acquisitions, including measurement period adjustments(1)	3.4		7.1		10.5
Effect of foreign currency translation	—		(16.7)		(16.7)
Goodwill, December 31, 2022	2,149.2		165.6		2,314.8
Acquisitions, including measurement period adjustments	—		62.8		62.8
Effect of foreign currency translation	—		8.6		8.6
Goodwill, December 31, 2023	$	2,149.2	$	237.0	$	2,386.2
__________________________

(1) North America goodwill recorded during the year ended December 31, 2022 relates to a measurement period adjustment for income taxes for Homes.com of $3.4 million. International goodwill recorded in connection with the Business Immo Acquisition was $7.1 million.

(2) International goodwill generated during the year ended December 31, 2023 from the OnTheMarket Acquisition was $62.8 million.

Goodwill generated from acquisitions completed in 2023 and 2022 was not deductible for tax purposes.

No impairments of the Company's goodwill were recognized during each of the years ended December 31, 2023, 2022 and 2021.

10.    INTANGIBLE ASSETS

Intangible assets consist of the following (in millions, except amortization period data):

F-29

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

	December 31,				Weighted- Average Amortization Period (in years)
	2023		2022
Acquired technology and data	$	36.3	$	40.4	5
Accumulated amortization	(21.0)		(20.7)
Acquired technology and data, net	15.3		19.7
Acquired customer base	509.5		464.2		10
Accumulated amortization	(330.7)		(287.0)
Acquired customer base, net	178.8		177.2
Acquired trade names and other intangible assets	258.9		247.4		13
Accumulated amortization	(139.3)		(115.0)
Acquired trade names and other intangible assets, net	119.6		132.4
Intangible assets, net	$	313.7	$	329.3

Amortization expense for intangible assets was approximately $73.7 million, $102.6 million and $103.6 million for the years ended December 31, 2023, 2022 and 2021, respectively. For the years ended December 31, 2023, 2022 and 2021, the Company removed $7.4 million, $87.7 million, and $171.0 million, respectively, of intangible assets that were fully amortized from the acquired intangible assets and accumulated amortization, which had no net impact on the Company's financial results.

In the aggregate, the Company expects the future amortization expense for intangible assets existing as of December 31, 2023 to be approximately $70.8 million, $54.8 million, $43.3 million, $34.7 million and $30.8 million for the years ending December 31, 2024, 2025, 2026, 2027 and 2028, respectively.

Intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. No impairments of the Company's intangible assets were recognized during each of the years ended December 31, 2023, 2022 and 2021. The Company decided to eliminate usage fees related to agent access to a Homesnap product charged to a specific customer class. This resulted in an acceleration of $16.3 million of amortization expense in 2022 for acquired customer base for this customer class.

11.    LONG-TERM DEBT

The table below presents the components of outstanding debt (in millions):

	December 31,
	2023		2022
2.800% Senior Notes due July 15, 2030	$	1,000.0	$	1,000.0
2020 Credit Agreement, due July 1, 2025	—		—
Total face amount of long-term debt	1,000.0		1,000.0
Senior Notes unamortized discount and issuance costs	(9.5)		(10.8)
Long-term debt, net	$	990.5	$	989.2

Senior Notes

On July 1, 2020, the Company issued $1.0 billion aggregate principal amount of 2.800% Senior Notes due July 15, 2030. The Senior Notes were sold to a group of financial institutions as initial purchasers who subsequently resold the Senior Notes to non-U.S. persons pursuant to Regulation S under the Securities Act, and to persons reasonably believed to be qualified institutional buyers pursuant to Rule 144A under the Securities Act at a purchase price equal to 99.921% of their principal amount. Interest on the Senior Notes is payable semi-annually in arrears on January 15 and July 15. The Senior Notes may be redeemed in whole or in part by the Company (a) at any time prior to April 15, 2030 at a redemption price equal to 100% of the principal amount of the Senior Notes, plus the Applicable Premium (as calculated in accordance with the indenture governing

F-30

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

the Senior Notes), and any accrued and unpaid interest, if any, on the principal amount of Senior Notes being redeemed to, but excluding, the redemption date, and (b) on or after April 15, 2030 at a redemption price equal to 100% of the principal amount of the Senior Notes, plus any accrued and unpaid interest, if any, on the principal amount of Senior Notes being redeemed to, but excluding, the redemption date. The Company’s obligations under the Senior Notes are guaranteed on a senior, unsecured basis by the Company’s domestic wholly owned subsidiaries and the indenture governing the Senior Notes contains covenants, events of default and other customary provisions with which the Company was in compliance as of December 31, 2023.

Revolving Credit Facility

On July 1, 2020, the Company entered into the 2020 Credit Agreement, which provides for a $750 million revolving credit facility with a term of five years (maturing July 1, 2025) and a letter of credit sublimit of $20 million from a syndicate of financial institutions as lenders and issuing banks. A commitment fee of 0.25% to 0.30% per annum, depending on the Total Leverage Ratio (defined in 2020 Credit Agreement), is payable quarterly in arrears based on the unused revolving commitment. The Company and the syndicate of lenders and issuing banks entered into the First Amendment of the 2020 Credit Agreement in May 2023, which replaced LIBOR as the reference rate with Term SOFR for U.S. dollar denominated borrowings, SONIA rates for Sterling denominated borrowings and EURIBOR for Euro denominated borrowings.

Borrowings under the 2020 Credit Agreement can be on a revolving basis or term basis, not to exceed the remaining term of the facility, and denominated in U.S. dollars, sterling, euros or other allowed currency at the Company's option, subject to a limit of $250 million U.S. dollar equivalent for non-U.S. dollar denominated borrowings. Borrowings bear interest at a floating rate which can be, at the Company’s option, either (a) an alternate base rate plus an applicable rate ranging from 0.50% to 1.25% or (b) a Term SOFR, SONIA rate or EURIBOR (with a floor of 0.0%) for the specified interest period plus an applicable rate ranging from 1.50% to 2.25%, in each case depending on the Company's Total Leverage Ratio (as defined in the 2020 Credit Agreement). Any borrowing with a Term SOFR reference rate includes an additional 0.10% credit spread adjustment.

Funds drawn down on the revolving credit facility pursuant to the 2020 Credit Agreement may be used for working capital and other general corporate purposes of the Company and its restricted subsidiaries. The obligations under the 2020 Credit Agreement are guaranteed by each of the Company’s current and future direct or indirect wholly owned restricted domestic subsidiaries, other than certain excluded subsidiaries, in each case subject to certain exceptions, pursuant to guarantee agreements.

The 2020 Credit Agreement includes covenants, including ones that, subject to certain exceptions, restrict the ability of the Company and its subsidiaries to (i) incur additional indebtedness, (ii) incur liens, (iii) pay dividends or make certain other restricted payments, investments or acquisitions, (iv) merge or consolidate with another person, and (v) sell, assign, lease or otherwise dispose of all or substantially all of our assets. In May 2023, the Company amended the 2020 Credit Agreement to replace LIBOR as the reference rate with Term SOFR for U.S. dollar-denominated borrowings, SONIA rates for Sterling-denominated borrowings and EURIBOR for Euro-denominated borrowings.

As of December 31, 2023, the Company is in a Covenant Suspension Period. During any Covenant Suspension Period, the Company will not be subject to certain of these covenants such as restrictions on the ability to incur indebtedness. The 2020 Credit Agreement also requires the Company to maintain a Total Leverage Ratio (as defined in the 2020 Credit Agreement) not exceeding 4.50 to 1.00. The Company was in compliance with the covenants in the 2020 Credit Agreement as of December 31, 2023.

As of December 31, 2023, the Company had no amounts drawn under this facility.

The Company had $1.6 million and $2.7 million of deferred debt issuance costs as of December 31, 2023 and 2022, respectively, in connection with the 2020 Credit Agreement. These amounts are included in deposits and other assets on the Company's consolidated balance sheets.

F-31

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

For the years ended December 31, 2023, 2022 and 2021, the Company recognized interest expense as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Interest on outstanding borrowings	$	28.0	$	28.0	$	28.0
Amortization of Senior Notes discount and issuance costs	2.4		2.3		2.3
Interest capitalized for construction in process	(1.6)		—		—
Commitment fees and other	2.6		2.0		2.0
Total interest expense	$	31.4	$	32.3	$	32.3

F-32

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

12.    INCOME TAXES

The components of the provision for income taxes attributable to operations consist of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
Current:
Federal	$	126.3	$	116.3	$	61.3
State	36.6		31.2		24.6
Foreign	0.9		0.7		1.3
Total current	163.8		148.2		87.2
Deferred:
Federal	(31.7)		(20.4)		22.9
State	(2.9)		(9.6)		8.5
Foreign	(2.6)		(1.2)		(7.2)
Total deferred	(37.2)		(31.2)		24.2
Total provision for income taxes	$	126.6	$	117.0	$	111.4

The components of deferred tax assets and liabilities consist of the following (in millions):

	December 31,
	2023		2022
Deferred tax assets:
Allowance for credit losses	$	5.8	$	3.4
Accrued compensation	11.9		4.6
Stock compensation	15.3		20.4
Net operating losses	34.7		26.8
Accrued reserve and other	5.8		6.7
Lease liabilities	21.8		26.4
Capitalized research and development costs	92.4		45.4
Research and development credits	4.5		6.1
Total deferred tax assets, prior to valuation allowance	192.2		139.8
Valuation allowance	(9.0)		(5.2)
Total deferred tax assets, net of valuation allowance	183.2		134.6
Deferred tax liabilities:
Deferred commission costs, net	(42.3)		(36.1)
Lease right-of-use assets	(16.0)		(18.2)
Prepaid expenses	(4.1)		(3.2)
Property and equipment, net	(25.1)		(25.8)
Intangible assets, net	(128.1)		(117.8)
Total deferred tax liabilities	(215.6)		(201.1)
Net deferred tax liabilities	$	(32.4)	$	(66.5)

For both the years ended December 31, 2023 and 2022, the Company has not recognized deferred tax liabilities for temporary differences related to investments in foreign subsidiaries that were deemed permanently reinvested. Determination of the amount of unrecognized deferred income tax liabilities on these earnings is not practicable because such liability, if any, depends on certain circumstances existing if and when remittance occurs. A deferred tax liability will be recognized if and when the Company no longer plans to permanently reinvest these undistributed earnings.

As of both December 31, 2023 and 2022, a valuation allowance has been established for certain deferred tax assets due to the uncertainty of realization. The valuation allowance as of both December 31, 2023 and 2022 includes an allowance for acquired net operating losses and foreign deferred tax assets.

F-33

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The Company established the valuation allowance because it is more likely than not that a portion of the deferred tax asset for certain items will not be realized based on the weight of available evidence. A valuation allowance was established for the foreign deferred tax assets due to the cumulative loss in recent years in those jurisdictions. The Company has not had sufficient taxable income historically to utilize the foreign deferred tax assets, and it is uncertain whether the Company will generate sufficient taxable income in the future to utilize the deferred tax assets. The Company has established a valuation allowance for certain acquired net operating losses where Section 382 limitations will impact the ability of the Company to utilize the net operating losses before they expire.

The Company’s change in valuation allowance was an increase of approximately $3.8 million for the year ended December 31, 2023 and a decrease of approximately $0.5 million for the year ended December 31, 2022. The increase for the year ended December 31, 2023 was primarily due to an increase in foreign net operating loss deferred tax assets for which a full valuation allowance has been established. The decrease for the year ended December 31, 2022 was primarily due to an international restructuring.

The Company had U.S. income before income taxes of approximately $526.7 million, $493.2 million and $408.8 million for the years ended December 31, 2023, 2022 and 2021, respectively. The Company had foreign losses before income taxes of approximately $25.4 million, $6.7 million and $4.8 million for the years ended December 31, 2023, 2022 and 2021, respectively.

The Company’s provision for income taxes resulted in effective tax rates that varied from the statutory federal income tax rate as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Expected federal income tax provision at statutory rate	$	105.3	$	102.1	$	84.8
State income taxes, net of federal benefit	27.4		21.5		21.0
Increase (decrease) in valuation allowance	1.9		(0.5)		(5.0)
Research credits	(20.2)		(17.5)		(13.1)
Excess tax benefit	(5.9)		(1.8)		(10.9)
Tax reserves	4.2		1.5		(12.8)
Nondeductible compensation	8.8		11.4		10.4
International restructuring	0.1		(3.9)		34.9
Other adjustments	5.0		4.2		2.1
Income tax expense	$	126.6	$	117.0	$	111.4

The Company has net operating loss carryforwards for international income tax purposes of approximately $77.3 million that do not expire. The Company has federal net operating loss carryforwards of approximately $71.3 million that begin to expire in 2033, state net operating loss carryforwards with a tax value of approximately $0.4 million that begin to expire in 2033 and state income tax credit carryforwards with a tax value of approximately $8.0 million primarily relating to state research and development credits and the D.C. qualified high technology company tax credit that begin to expire in 2024. The Company realized a cash benefit relating to the use of its tax loss carryforwards of approximately $5.9 million, $12.6 million and $14.1 million in December 31, 2023, 2022 and 2021, respectively.

F-34

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The following table summarizes the activity related to the Company’s unrecognized tax benefits (in millions):

Unrecognized tax benefit as of December 31, 2020	$	28.9
Increase for current year tax positions	3.1
Decrease for prior year tax positions	(5.4)
Decrease for settlements with taxing authorities	(9.9)
Expiration of the statute of limitation for assessment of taxes	(1.9)
Unrecognized tax benefit as of December 31, 2021	14.8
Increase for current year tax positions	3.4
Increase for prior year tax positions	0.3
Expiration of the statute of limitation for assessment of taxes	(2.3)
Unrecognized tax benefit as of December 31, 2022	16.2
Increase for current year tax positions	4.4
Increase for prior year tax positions	1.7
Expiration of the statute of limitation for assessment of taxes	(2.4)
Unrecognized tax benefit as of December 31, 2023	$	19.9

Approximately $19.9 million and $16.2 million of the unrecognized tax benefits as of December 31, 2023 and 2022, respectively, would favorably affect the annual effective tax rate if recognized in future periods. The increase for current year tax positions of $4.4 million and increase for prior year tax positions of $1.7 million for the year ended December 31, 2023 were primarily attributable to research credits and state apportionment reserves. The decrease for expiration of the statute of limitation of $2.4 million for the year ended December 31, 2023 was attributable to research credits. The Company recognized $0.7 million, recognized $0.1 million and reversed $0.4 million for interest and penalties in its consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021, respectively. The Company had liabilities of $1.4 million, $0.7 million, and $0.6 million for interest and penalties in its consolidated balance sheets as of December 31, 2023, 2022 and 2021, respectively. The Company does not anticipate the amount of the unrecognized tax benefits will change significantly over the next 12 months.

The Company is subject to taxation in the U.S. federal jurisdiction and various states and foreign jurisdictions. The Company’s federal income tax returns for tax years 2015 and 2020 through 2022 remain open to examination. Most of the Company’s state income tax returns for tax years 2020 through 2022 remain open to examination. For states that have a four-year statute of limitations, the state income tax returns for tax years 2019 through 2022 remain open to examination. The Company’s U.K. income tax return for tax year 2022 remains open to examination. The Company believes that an adequate provision has been made for any adjustments that may result from tax examinations.

13.    COMMITMENTS AND CONTINGENCIES

The following summarizes the Company's significant contractual obligations, including related payments due by period, as of December 31, 2023 (in millions):

Year Ending December 31,	Operating lease obligations		Finance lease obligations		Long-term debt principal payments		Long-term debt principal interest payments
2024	$	39.0	$	3.9	$	—	$	28.0
2025	25.4		3.9		—		28.0
2026	15.1		3.9		—		28.0
2027	13.1		2.9		—		28.0
2028	10.7		—		—		28.0
Thereafter	6.6		—		1,000.0		56.0
Total	$	109.9	$	14.6	$	1,000.0	$	196.0

The Company leases office facilities under various non-cancelable operating leases, as well as, data centers, and vehicles under finance lease arrangements. The leases contain various renewal options.

F-35

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

See Note 7 for further discussion of the Company's lease commitments.

Currently, and from time to time, the Company is involved in litigation incidental to the conduct of its business. The Company records a provision for a liability when it is both probable that a liability has been incurred and the amount can be reasonably estimated. While it is reasonably possible that an unfavorable outcome may occur as a result of one or more of the Company’s current litigation matters, at this time management has concluded that the resolutions of these matters are not expected to have a material effect on the Company's consolidated financial position, future results of operations or liquidity. Legal defense costs are expensed as incurred.

F-36

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

14.    SEGMENT REPORTING

Segment Information

The Company manages its business geographically in two operating segments, with the primary areas of measurement and decision-making being North America, which includes the U.S. and Canada, and International, which primarily includes Europe, Asia-Pacific and Latin America. Management relies on an internal management reporting process that provides revenue and operating segment EBITDA. Management believes that operating segment EBITDA is an appropriate measure for evaluating the operational performance of the Company’s operating segments. EBITDA is used by management to internally measure operating and management performance and to evaluate the performance of the business. However, this measure should be considered in addition to, not as a substitute for or superior to, income from operations or other measures of financial performance prepared in accordance with GAAP.

Summarized EBITDA information by operating segment consists of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
North America	$	403.0	$	577.3	$	557.1
International	(13.2)		5.4		7.9
Total EBITDA	$	389.8	$	582.7	$	565.0

The reconciliation of net income to EBITDA consists of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
Net income	$	374.7	$	369.5	$	292.6
Amortization of acquired intangible assets in cost of revenues	31.5		29.0		28.8
Amortization of acquired intangible assets in operating expenses	42.2		73.6		74.8
Depreciation and other amortization	33.8		29.1		29.1
Interest (income) expense, net	(213.6)		(32.1)		31.6
Other (income), net	(5.4)		(3.4)		(3.3)
Income tax expense	126.6		117.0		111.4
EBITDA	$	389.8	$	582.7	$	565.0

37

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

Summarized information by operating segment consists of the following (in millions):

	December 31,
	2023		2022
Property and equipment, net
North America	$	465.7	$	320.3
International	6.5		1.0
Total property and equipment, net	$	472.2	$	321.3
Goodwill
North America	$	2,149.2	$	2,149.2
International	237.0		165.6
Total goodwill	$	2,386.2	$	2,314.8
Assets
North America	$	8,505.5	$	8,146.3
International	414.2		256.2
Total assets	$	8,919.7	$	8,402.5
Liabilities
North America	$	1,499.7	$	1,486.3
International	81.4		46.2
Total liabilities	$	1,581.1	$	1,532.5

F-38

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

15.    STOCKHOLDER'S EQUITY

Preferred Stock

The Company has 2 million shares of preferred stock, $0.01 par value, authorized for issuance. The Board of Directors may issue the preferred stock from time to time as shares of one or more classes or series.

Common Stock

The Company has 1.2 billion shares of common stock, $0.01 par value, authorized for issuance. Dividends may be declared and paid on the common stock, subject in all cases to the rights and preferences of the holders of preferred stock and authorization by the Board of Directors. In the event of liquidation or winding up of the Company and after the payment of all preferential amounts required to be paid to the holders of any series of preferred stock, any remaining funds shall be distributed among the holders of the issued and outstanding common stock.

Common Stock Split

At the Company's 2021 Annual Meeting of Stockholders in June 2021, upon the recommendation of the Company's Board of Directors, the Company's stockholders approved the adoption of the Company's Fourth Amended and Restated Certificate of Incorporation, which increased the total number of shares of common stock that the Company is authorized to issue from 60 million to 1.2 billion. The Fourth Amended and Restated Certificate of Incorporation became effective on June 7, 2021. On June 7, 2021, the Board of Directors approved a ten-for-one stock split of the Company's outstanding shares of common stock to be effected in the form of a stock dividend. Each stockholder of record on June 17, 2021 received a dividend of nine additional shares of common stock for each then-held share, distributed after close of trading on June 25, 2021. The par value of the Company's common stock remained $0.01 per share. All applicable share and per-share amounts in the consolidated financial statements and the accompanying notes have been retroactively adjusted to reflect the impact of the stock split.

Equity Offerings

On September 20, 2022, the Company completed a public equity offering of 10.7 million shares of common stock at an offering price of $70.38 per share. Net proceeds from the public equity offering were approximately $745.7 million, after deducting approximately $4.3 million of underwriting fees, commissions and other stock issuance costs. On May 28, 2020, the Company completed a public equity offering of 26.3 million shares of common stock for $65.50 per share. Net proceeds from the public equity offering were approximately $1.7 billion, after deducting approximately $35 million of underwriting fees, commissions and other stock issuance costs. The Company intends to use the net proceeds from the sale of the securities to fund all or a portion of the costs of any strategic acquisitions it pursues in the future, to finance the growth of its business and for working capital and other general corporate purposes. General corporate purposes may include additions to working capital, capital expenditures, repayment of debt, investments in the Company’s subsidiaries and the repurchase, redemption or retirement of securities, including the Company’s common stock.

F-39

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS  

16.    NET INCOME PER SHARE

The following table sets forth the calculation of basic and diluted net income per share (in millions, except per share data):

	Year Ended December 31,
	2023		2022		2021
Numerator:
Net income	$	374.7	$	369.5	$	292.6
Denominator:
Denominator for basic net income per share — weighted-average outstanding shares	405.3		396.3		392.2
Effect of dilutive securities:
Stock options, restricted stock awards and restricted stock units	1.6		1.5		2.0
Denominator for diluted net income per share — weighted-average outstanding shares	406.9		397.8		394.2
Net income per share — basic	$	0.92	$	0.93	$	0.75
Net income per share — diluted	$	0.92	$	0.93	$	0.74

The following table summarizes the shares underlying the unvested performance-based restricted stock and anti-dilutive securities excluded from the basic and diluted earnings per share calculations (in millions):

	Year Ended December 31,
	2023	2022	2021
Performance-based restricted stock awards	0.2	0.4	0.4
Anti-dilutive securities	0.7	1.0	0.4

17.    EMPLOYEE BENEFIT PLANS

Stock Incentive Plans

In April 2007, the Company’s Board of Directors adopted the CoStar Group 2007 Stock Incentive Plan (as amended, the “2007 Plan”), subject to stockholder approval, which was obtained on June 7, 2007. In April 2016, the Company’s Board of Directors adopted the CoStar Group 2016 Stock Incentive Plan (as amended, the “2016 Plan”), subject to stockholder approval, which was obtained on June 9, 2016. All shares of common stock that were authorized for issuance under the 2007 Plan that, as of June 9, 2016, remained available for issuance under the 2007 Plan (excluding shares subject to outstanding awards) were rolled into the 2016 Plan and, as of that date, no shares of common stock were available for new awards under the 2007 Plan. The 2007 Plan continues to govern vested unexercised stock options issued prior to June 9, 2016. Upon the occurrence of a Change of Control, as defined in the 2007 Plan, all outstanding unexercisable options under the 2007 Plan immediately become exercisable.

The 2016 Plan provides for the grant of stock options, restricted stock, restricted stock units and stock appreciation rights to officers, employees and directors of the Company and its subsidiaries. Stock options granted under the 2016 Plan may be non-qualified or may qualify as incentive stock options. Except in limited circumstances related to a merger or other acquisition, the exercise price for an option may not be less than the fair market value of the Company’s common stock on the date of grant. The vesting period for each grant of options, restricted stock, restricted stock units and stock appreciation rights under the 2016 Plan is determined by the Board of Directors or a committee thereof and is generally three to four years, subject to minimum vesting periods for restricted stock and restricted stock units of at least one year. In some cases, vesting of awards under the 2016 Plan may be based on performance conditions. The Company initially reserved approximately 22.7 million shares of common stock for issuance under the 2016 Plan, which included shares of common stock that were authorized and remained available for issuance under the 2007 Plan as of June 9, 2016. Any shares of common stock subject to (a) outstanding awards under the 2007 Plan as of June 9, 2016 or (b) outstanding awards under the 2016 Plan after June 9, 2016, that cease for any reason to be subject to such awards (other than by reason of exercise or settlement of the awards to the extent they are exercised or settled in vested and nonforfeitable shares) will become authorized and unissued under the 2016 Plan. Pursuant to the terms of the 2016 Plan, all amounts reserved or issued under the plan were adjusted to reflect the Company’s ten-for-one common stock split. Unless terminated sooner, the 2016 Plan will terminate in June 2026, but will continue to govern

F-40

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

unexercised and unexpired awards issued under the 2016 Plan prior to that date. Approximately 13.4 million shares were available for future grant under the 2016 Plan as of December 31, 2023.

At December 31, 2023, there was approximately $115.3 million of unrecognized compensation cost related to stock incentive plans, net of estimated forfeitures, which the Company expects to recognize over a weighted-average-period of 2.4 years. The income tax benefit realized from stock-based compensation was $6.8 million, immaterial  and $2.4 million for the years ended December 31, 2023, 2022 and 2021, respectively.

See Notes 2 and 12 for further discussion of stock-based compensation expense and income taxes, respectively.

Stock Options

Option activity was as follows:

	Number of Shares	Range of Exercise Price	Weighted- Average Exercise Price		Weighted- Average Remaining Contract Life (in years)	Aggregate Intrinsic Value (in millions)
Outstanding at December 31, 2020	2,023,100	$10.22 - $66.65	$	34.18	6.99	$	117.8
Granted	159,000	$91.98	$	91.98
Exercised	(206,000)	$20.49 - $39.82	$	30.78
Outstanding at December 31, 2021	1,976,100	$10.22 - $91.98	$	39.18	6.24	$	80.8
Granted	202,100	$67.29	$	67.29
Exercised	—
Canceled or expired	—
Outstanding at December 31, 2022	2,178,200	$10.22 - $91.98	$	41.79	5.60	$	79.6
Granted	140,800	$76.78	$	76.78
Exercised	(419,340)	$10.22 - $34.21	$	17.77
Canceled or expired	—
Outstanding at December 31, 2023	1,899,660	$20.49 - $91.98	$	49.69	5.53	$	72.4
Exercisable at December 31, 2021	1,473,420	$10.22 - $66.65	$	29.55	5.59	$	72.9
Exercisable at December 31, 2022	1,766,070	$10.22 - $91.98	$	34.40	4.96	$	76.5
Exercisable at December 31, 2023	1,571,105	$20.49 - $91.98	$	44.32	4.93	$	68.1

The aggregate intrinsic value of outstanding options is calculated as the difference between (i) the closing price of the common stock at the end of the period and (ii) the exercise price of the underlying awards, multiplied by the number of outstanding options as of the end of the period that had an exercise price less than the closing price on that date. The aggregate intrinsic value of options exercised, determined as of the exercise date, was approximately $24.3 million and $11.0 million for the years ended December 31, 2023 and 2021, respectively. No options were exercised in the year ended December 31, 2022.

The Company estimated the fair value of each option granted on the date of grant using the Black-Scholes option-pricing model, using the assumptions in the following table:

	Year Ended December 31,
	2023			2022			2021
Dividend yield	0		%	0		%	0		%
Expected volatility	35		%	31		%	30		%
Risk-free interest rate	3.96		%	1.89		%	0.56		%
Expected life (in years)	5			5			5
Weighted-average grant date fair value	$	28.87		$	20.43		$	25.09

F-41

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The expected dividend yield is determined based on the Company's past cash dividend history and anticipated future cash dividend payments. The Company has never declared nor paid any dividends on its common stock and does not anticipate paying any dividends on its common stock during the foreseeable future, but intends to retain any earnings for future growth of its business. Expected volatility is calculated based on historical volatility of the daily closing price of the Company's common stock over a period consistent with the expected life of the options granted. The risk-free interest rate is based on the U.S. Treasury rate with terms similar to the expected life of the options granted. The expected life for the options is determined based on multiple factors, including historical employee behavior patterns of exercising options and post-employment termination behavior as well as expected future employee option exercise patterns.

The following table summarizes information regarding options outstanding at December 31, 2023:

	Options Outstanding				Options Exercisable
Range of Exercise Price	Number of Shares	Weighted-Average Remaining Contractual Life (in years)	Weighted- Average Exercise Price		Number of Shares	Weighted- Average  Exercise Price
$20.49 - $27.35	346,000	3.16	$	20.49	346,000	$	20.49
$27.36 - $37.02	354,090	4.16	$	34.21	354,090	$	34.21
$37.03 - $53.24	385,670	5.10	$	39.82	385,670	$	39.82
$53.25 - $66.97	312,000	6.10	$	66.65	312,000	$	66.65
$66.98 - $91.98	501,900	8.09	$	77.77	173,345	$	82.39
	1,899,660	5.53	$	49.69	1,571,105	$	44.32

Restricted Stock Awards

The Compensation Committee of the Board of Directors of the Company historically approved grants of restricted common stock to employees and directors of the Company that vest over a specific service period and to executive officers that vest based on the achievement of certain performance conditions, primarily, the achievement of a three-year cumulative revenue goal established at the grant date. The grant of awards with performance conditions supports the Company’s goal of aligning executive incentives with long-term stockholder value and ensuring that executive officers have a continuing stake in the long-term success of the Company.

The vesting of restricted common stock is subject to continuing employment requirements. Certain performance-based restricted common stock awards are also subject to a market condition such that the actual number of shares that vest at the end of the respective three-year period is determined based on the Company’s achievement of performance goals and an established Company specific TSR factor relative to the S&P 500 Index over the same three-year performance period. At the end of the three-year performance period, if the performance condition is achieved at or above the pre-established threshold, the number of shares earned is further adjusted by a TSR payout percentage, which ranges between 80% and 120%, based on the Company’s TSR performance relative to that of S&P 500 Index over the respective three-year period.

The Company estimates the fair value of its equity awards with both a performance and market condition on the date of grant using a Monte-Carlo simulation valuation model. This pricing model uses multiple simulations to evaluate the probability of achieving the market condition to calculate the fair value of the awards. Expense is only recorded for awards that are expected to vest, net of estimated forfeitures. The assumptions used to estimate the fair value of awards with both a performance and a market condition were as follows:

	Year Ended December 31,
	2023			2022			2021
Dividend yield	0		%	0		%	0		%
Expected volatility	37		%	34		%	42		%
Risk-free interest rate	4.31		%	1.71		%	0.20		%
Expected life (in years)	3			3			3
Weighted-average grant date fair value	$	81.58		$	71.19		$	99.73

F-42

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

The expected dividend yield is determined based on the Company's past cash dividend history and anticipated future cash dividend payments. The Company has never declared nor paid any dividends on its common stock and does not anticipate paying any dividends on its common stock during the foreseeable future, but intends to retain any earnings for future growth of its business. Expected volatility is calculated based on historical volatility of the daily closing price of the common stock of the companies within the S&P 500 Index over a period consistent with the expected life of the awards. The risk-free interest rate is based on the U.S. Treasury rate with terms similar to the expected life of the awards. The expected life is consistent with the performance measurement period of the awards.

As of December 31, 2023, the Company determined that it was probable that at least the minimum performance goals associated with restricted stock awards with performance and market conditions granted during 2023, 2022 and 2021 would be met by their forfeiture dates. The Company recorded a total of approximately $13.6 million, $11.9 million and $8.0 million of stock-based compensation expense related to restricted stock awards with performance and market conditions for the years ended December 31, 2023, 2022 and 2021, respectively. As of December 31, 2023, the Company expects to record an aggregate stock-based compensation expense of approximately $14.0 million for restricted stock awards with performance and market conditions over the periods 2024, 2025 and 2026.

The following table presents unvested restricted stock awards activity for the year ended December 31, 2023:

	Restricted Stock Awards — without Market Condition			Restricted Stock Awards — with Market Condition
	Number of Shares	Weighted-Average Grant Date Fair Value per Share		Number of Shares	Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock awards at December 31, 2022	2,061,894	$	67.15	620,880	$	80.55
Granted	1,096,446	$	73.27	283,440	$	81.58
Vested	(787,883)	$	66.51	(90,408)	$	72.69
Canceled	(230,546)	$	68.58	(132,792)	$	72.69
Unvested restricted stock awards at December 31, 2023	2,139,911	$	70.38	681,120	$	83.56

Restricted Stock Units

The following table presents unvested restricted stock units activity for the year ended December 31, 2023:

	Number of Units	Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock units at December 31, 2022	21,560	$	65.24
Granted	10,465	$	70.74
Vested	(8,129)	$	65.77
Canceled	(977)	$	68.34
Unvested restricted stock units at December 31, 2023	22,919	$	67.43

Management Stock Purchase Plan

The Board of Directors adopted the Company’s Management Stock Purchase Plan in December 2017 with the intent of providing selected key employees of the Company and its subsidiaries, including the Company's executive officers, the opportunity to defer a portion of their cash incentive compensation and to align management and stockholder interests through awards of DSUs under the MSPP and awards of Matching RSUs issued under the 2016 Plan. Under this plan participants are permitted to elect to defer up to 100% of their annual incentive bonus or commissions earned during the year by submitting an irrevocable election in accordance with Section 409A of the Internal Revenue Code, as amended. On the date the incentive bonus or commission would otherwise be paid in cash (typically during the following calendar year), the Company awards the participant DSUs representing the number of shares of common stock with an aggregate fair market value on that date equal to the amount of compensation elected to be deferred under the MSPP. On the same date the DSUs are awarded, the participant

F-43

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

receives a grant of Matching RSUs covering the number of shares of common stock equal up to 100% of the DSUs granted. The expense related to the DSUs is recognized on a straight-line basis during the period that the related incentive bonus or commission is earned. The Company granted 82,374 and 75,479 DSUs during the years 2023 and 2022, respectively. The expense related to the Matching RSUs is recognized over the four-year vesting period following the grant date.

The following tables presents the Matching RSU activity for the year ended December 31, 2023:

	Number of Matching RSU Shares	Weighted-Average Grant Date Fair Value per Share
Unvested MSPP restricted stock units at December 31, 2022	180,431	$	60.52
Granted	82,374	$	67.36
Vested	(52,710)	$	46.91
Canceled	(13,128)	$	66.67
Unvested MSPP restricted stock units at December 31, 2023	196,967	$	66.61

Employee 401(k) Plan

The Company maintains a 401(k) Plan as a defined contribution retirement plan for all eligible employees. The 401(k) Plan provides for tax-deferred contributions of employees’ salaries, limited to a maximum annual amount as established by the IRS. In addition to the traditional 401(k), effective January 1, 2015, eligible employees have the option of making an after-tax contribution to a Roth 401(k) plan or a combination of both. In each of 2023, 2022 and 2021, the Company matched 100% of employee contributions up to a maximum of 4% of total compensation. Amounts contributed to the 401(k) Plan by the Company to match employee contributions for the years ended December 31, 2023, 2022 and 2021 were approximately $25.5 million, $21.5 million and $17.6 million, respectively. The Company had no administrative expenses in connection with the 401(k) Plan for each of the years ended December 31, 2023, 2022 and 2021.

Employee Pension Plan

The Company maintains a GPP Plan for all eligible employees in the Company’s U.K. offices. The GPP Plan is a defined contribution plan. Employees are eligible to contribute a portion of their salaries, subject to a maximum annual amount as established by Her Majesty's Revenue and Customs. In each of 2023, 2022 and 2021, the Company's matching contribution was based on the percentage contributed by the employee, up to a maximum of 6% of total compensation. Amounts contributed to the GPP Plan by the Company to match employee contributions for the years ended December 31, 2023, 2022 and 2021, were approximately $1.2 million, $1.0 million and $0.9 million, respectively.

Registered Retirement Savings Plan

As of January 1, 2015, the Company introduced a RRSP for all eligible employees in the Company’s Canadian offices. In each of the years ended December 31, 2023, 2022 and 2021, the Company matched 100% of employee contributions up to a maximum of 4% of total compensation. Amounts contributed to the RRSP by the Company to match employee contributions were approximately $0.2 million for the year ended December 31, 2023, and $0.1 million for both of the years ended December 31, 2022 and 2021.

Employee Stock Purchase Plan

As of August 1, 2006, the Company introduced an ESPP, pursuant to which eligible employees participating in the plan authorize the Company to withhold specified amounts from the employees’ compensation and use the withheld amounts to purchase shares of the Company's common stock at 90% of the market price. Participating employees are able to purchase common stock under this plan during each offering period. An offering period begins the second Saturday before each of the Company’s regular pay dates and ends on each of the Company’s regular pay dates. On June 2, 2021, the Company’s stockholders approved an amendment to the ESPP to increase the number of shares available for purchase under the ESPP by 1 million shares. The Company registered the issuance of these additional shares under the ESPP pursuant to the registration statement filed on July 28, 2021. There were 782,328 and 1,010,267 shares available for purchase under the ESPP as of December 31, 2023 and 2022, respectively, and approximately 227,939 and 223,596 shares of the Company’s common stock were purchased under the ESPP during 2023 and 2022, respectively. 

F-44

COSTAR GROUP, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

18.    SUBSEQUENT EVENTS

In January 2024, the Company entered into a conditional purchase and sale agreement for an office building in Arlington, Virginia. The Company closed on the transaction in February 2024 along with an agreement to purchase the land underlying the building. These transactions totaled $340.0 million, inclusive of property taxes, titling insurance and other transaction costs and were paid with cash on hand.

F-45

EX-10.22

Exhibit 10.22

CoStar Group, Inc.

Second Amended and Restated Employee Share Purchase Plan

Canadian Addendum

This addendum (the “Canadian Addendum”) to the CoStar Group, Inc. Second Amended and Restated Employee Share Purchase Plan (the “Plan”) shall form part of the Plan and will apply to eligible employees of CoStar Group, Inc. (the “Company”) and Designated Subsidiaries who are resident or employed in Canada (each a “Canadian Participant”)who participate in the Plan. Unless otherwise defined in this Canadian Addendum, the terms used herein shall have the meanings ascribed to them in the Plan.

By participating in, and purchasing Common Stock under, the Plan, each Canadian Participant represents, warrants and acknowledges as follows:

Canadian Securities Law Matters

1.The Canadian Participant’s participation in the trade and acceptance of Common Stock pursuant to the terms of the Plan is voluntary.

2.The Canadian Participant has not been induced to participate in the Plan by expectation of engagement, appointment, employment or continued engagement, appointment or employment, as applicable, by the Company or any Designated Subsidiary.

3.Participation in the Plan does not create the right or expectation for any additional grants of Common Stock or other securities of the Company.

4.Common Stock sold under the Plan are being distributed on a prospectus exempt basis in Canada. The Company is not a reporting issuer in any province or territory of Canada, the securities are not listed on any stock exchange in Canada, and the Company does not intend to become a reporting issuer or to list the securities on any stock exchange in Canada. As there is no market for the Common Stock in Canada, it may be difficult or even impossible for a Canadian Participant to sell their Common Stock in Canada. Any resale of Common Stock must be made in accordance with applicable securities laws in Canada, which may require resales to be made in accordance with or pursuant to an exemption from, or in a transaction not subject to, the prospectus requirements of applicable Canadian securities law. Canadian Participants are advised to seek legal advice prior to any resale of the Common Stock.

Tax Matters

5.The Company hereby provides notice to the Canadian Participant that, should the Company be a “specified person” within the meaning of section 110 of the Income Tax Act (Canada) (the “Canadian Tax Act”), the Common Stock issued hereunder will be designated as “non-qualified securities” and the Company will notify the Minister of National Revenue of Canada of any Common Stock that will be non-qualified securities on or before the filing-due date for the taxation year of the Company that includes the day on which the Common Stock are issued.

6.The Canadian Participant acknowledges that the difference between the fair market value of the Common Stock acquired and the Option Price paid by the Canadian Participant is a taxable benefit for the purposes of the Canadian Tax Act which will be reported in Box 14 and Box 38 of

Exhibit 10.22

the T4 slip, and which is subject to Canada Pension Plan premiums, but not Employment Insurance premiums.

7.Notwithstanding section 24 of the Plan, the Company shall not withhold any part of the Common Stock issued to a Canadian Participant to satisfy any withholding obligations related to the taxable benefit and the Canadian Participant acknowledges and agrees to make provision for such withholdings with the Administrator.

Employment Matters

8.For the purposes of section 11 of the Plan, the Canadian Participant’s employment will be deemed to terminate (and any reference to cessation of employment and cease to be an employee will have the same meaning as such deemed termination of employment) on the first date that the Canadian Participant ceases to be actively employed by the Company (or any subsidiary). The Canadian Participant agrees that they will not be considered to be actively employed or in active employment during any period or time in which the Canadian Participant receives or is required by applicable law to receive pay in lieu of notice or severance pay (except as may be required by the minimum extent of any applicable employment standards legislation). For further clarity, except as may be required by the minimum extent of any applicable employment standards legislation, the Canadian Participant will not be considered actively employed or in active employment even if they receive any compensation payments related to their termination (including resignation and constructive dismissal) or they are paid salary or other amounts thereby, including when receiving salary or other amounts in lieu of notice of termination.

For greater clarity, except as may be required by the minimum extent of any applicable employment standards legislation, if the Canadian Participant’s employment is terminated for any reason (including death), the Canadian Participant’s right (if any) to any benefit or any amounts with respect to such benefits under the Plan shall expire on the cessation of active employment, regardless of whether notice of termination is given or not given and regardless of whether the termination is lawful or unlawful (e.g., constructive dismissal). This includes where the Canadian Participant’s employment is terminated without cause or without notice and the Canadian Participant will not, except as may be required by the minimum extent of any applicable employment standards legislation, be entitled to an benefits or any amounts with respect to any benefit under the Plan as part of any common law right for compensation or damages related to any termination of employment (including resignation and constructive dismissal), including any loss of benefits that would have received during any notice period as part of any wrongful dismissal damages and including any damages for the manner of termination.

Miscellaneous

9.The Canadian Participant and the Company agree that this Canadian Addendum and all related documents be exclusively drawn up in English. Le Participant Canadien et la Compagnie consentent à ce que cette addenda canadien et tous les documents qui s’y rattachent soient exclusivement rédigés en français.

10.The Canadian Participant has received, or has had the opportunity to receive, independent legal advice in connection with the terms and conditions of the Plan, including this Canadian Addendum, and any Common Stock purchased thereunder.

Exhibit 10.22

11.All other provisions of the Plan shall continue to apply to Canadian Participants to the extent that they have not been specifically modified by this Canadian Addendum.

EX-21.1

EXHIBIT 21.1

Subsidiaries of the Registrant

Entity	Jurisdiction
Agents' Mutual Limited	United Kingdom
AM Tempco Limited	United Kingdom
BIH	France
Business Immo	France
Comreal Info	France
CoStar Central Place HQ, LLC	Delaware
CoStar Espana, S.L.	Spain
CoStar Field Research, LLC	Delaware
CoStar International, LLC	Delaware
CoStar Italy S.r.l.	Italy
CoStar Realty Information Canada Ltd.	British Columbia
CoStar Realty Information, Inc.	Delaware
CoStar UK Limited	United Kingdom
Cozy Insurance Services, LLC	Florida
Cozy Services, LLC	Delaware
Glanty LTD	United Kingdom
Grecam S.A.S.	France
Homes Media Solutions, LLC	Virginia
Homes.com, LLC	Delaware
Homesnap, LLC	Delaware
OnTheMarket PLC	United Kingdom
STR Australia Pty Ltd.	Australia
STR Benchmarking Indonesia	Indonesia
STR Benchmarking Solutions (Beijing) Co., Ltd	PRC
STR Columbia SAS	Columbia
STR Germany GmbH	Germany
STR Global Ltd.	United Kingdom
STR Global Singapore Private Limited	Singapore
STR Japan GK (STR Japan Limited)	Japan
STR, LLC	Delaware
Ten-X, Inc.	Delaware
Ten-X, Inc.	Connecticut
Ten-X, LLC	Delaware
The Screening Pros, LLC	California
Thomas Daily GmbH	Germany
Virginia Property Holdings II, LLC	Delaware

EX-23.1

EXHIBIT 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the following Registration Statements:

(1)	Registration Statement Number 333-135709 on Form S-8 pertaining to the CoStar Group, Inc. Employee Stock Purchase Plan,
(2)	Registration Statement Number 333-206929 on Form S-8 pertaining to the CoStar Group, Inc. Amended and Restated Employee Stock Purchase Plan,
(3)	Registration Statement Number 333-143968 on Form S-8 pertaining to the CoStar Group, Inc. 2007 Stock Incentive Plan, as amended,
(4)	Registration Statement Number 333-167424 on Form S-8 pertaining to the CoStar Group, Inc. 2007 Stock Incentive Plan, as amended,
(5)	Registration Statement Number 333-182377 on Form S-8 pertaining to the CoStar Group, Inc. 2007 Stock Incentive Plan, as amended,
(6)	Registration Statement Number 333-212278 on Form S-8 pertaining to the CoStar Group, Inc. 2016 Stock Incentive Plan,
(7)	Registration Statement Number 333-223230 on Form S-8 pertaining to the CoStar Group, Inc. Management Stock Purchase Plan, and
(8)	Registration Statement Number 333-258220 on Form S-8 of CoStar Group, Inc. pertaining to the Second Amended and Restated Employee Stock Purchase Plan.

of our reports dated February 21, 2024, with respect to the consolidated financial statements of CoStar Group, Inc. and the effectiveness of internal control over financial reporting of CoStar Group, Inc. included in this Annual Report (Form 10-K) of CoStar Group, Inc. for the year ended December 31, 2023.

/s/ Ernst & Young LLP

Tysons, Virginia

February 21, 2024

EX-31.1

EXHIBIT 31.1

CERTIFICATION

I, Andrew C. Florance, certify that:

1.I have reviewed this annual report on Form 10-K of CoStar Group, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date:	February 21, 2024	By:	/s/ Andrew C. Florance
			Andrew C. Florance
			President and Chief Executive Officer
			(Principal Executive Officer and Duly Authorized Officer)

EX-31.2

EXHIBIT 31.2

CERTIFICATION

I, Scott T. Wheeler certify that:

1.I have reviewed this annual report on Form 10-K of CoStar Group, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date:	February 21, 2024	By:	/s/ Scott T. Wheeler
			Scott T. Wheeler
			Chief Financial Officer
			(Principal Financial and Accounting Officer and Duly Authorized Officer)

EX-32.1

EXHIBIT 32.1

CoStar Group, Inc.

1331 L Street, NW

Washington, DC 20005

February 21, 2024

Securities and Exchange Commission

100 F Street, NE

Washington, DC  20549

Re:  Certification Of Principal Executive Officer Pursuant To 18 U.S.C.Sec. 1350

Dear Ladies and Gentlemen:

In connection with the accompanying Annual Report on Form 10-K of CoStar Group, Inc., for the year ended December 31, 2023, I, Andrew C. Florance, Chief Executive Officer of CoStar Group, Inc., hereby certify pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1)such Annual Report on Form 10-K of CoStar Group, Inc., for the year ended December 31, 2023, fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o (d)); and

2)the information contained in such Annual Report on Form 10-K of CoStar Group, Inc., for the year ended December 31, 2023, fairly presents, in all material respects, the financial condition and results of operations of CoStar Group, Inc.

By:	/s/ Andrew C. Florance
	Andrew C. Florance
	President and Chief Executive Officer
	(Principal Executive Officer and Duly Authorized Officer)

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to CoStar Group, Inc. and will be retained by CoStar Group, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.

In accordance with Item 601 of Regulation S-K, this certification is being “furnished” as Exhibit 32.1 to CoStar Group, Inc.’s annual report and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act, except as expressly set forth by specific reference in such a filing.

EX-32.2

EXHIBIT 32.2

CoStar Group, Inc.

1331 L Street, NW

Washington, DC 20005

February 21, 2024

Securities and Exchange Commission

100 F Street, NE

Washington, DC  20549

Re: Certification Of Principal Financial Officer Pursuant To 18 U.S.C. Sec. 1350

Dear Ladies and Gentlemen:

In connection with the accompanying Annual Report on Form 10-K of CoStar Group, Inc., for the year ended December 31, 2023, I, Scott T. Wheeler, Chief Financial Officer of CoStar Group, Inc., hereby certify pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1)such Annual Report on Form 10-K of CoStar Group, Inc., for the year ended December 31, 2023, fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C. 78m or 78o (d)); and

2)the information contained in such Annual Report on Form 10-K of CoStar Group, Inc., for the year ended December 31, 2023, fairly presents, in all material respects, the financial condition and results of operations of CoStar Group, Inc.

By:	/s/ Scott T. Wheeler
	Scott T. Wheeler
	Chief Financial Officer
	(Principal Financial and Accounting Officer and Duly Authorized Officer)

A signed original of this written statement required by Section 906, or other document authenticating, acknowledging or otherwise adopting the signature that appears in typed form within the electronic version of this written statement required by Section 906, has been provided to CoStar Group, Inc. and will be retained by CoStar Group, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.

In accordance with Item 601 of Regulation S-K, this certification is being “furnished” as Exhibit 32.2 to CoStar Group, Inc.’s annual report and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act, except as expressly set forth by specific reference in such a filing.

EX-97

Approved by the

CoStar Group, Inc.

Board of Directors

September 13, 2023

CoStar Group, Inc.

Policy for Recovery of Erroneously Awarded Compensation

CoStar Group, Inc. (the “Company”) has adopted this Policy for Recovery of Erroneously Awarded Compensation (the “Policy”), effective as of October 2, 2023 (the “Effective Date”), which Policy is an amendment and restatement of the Company’s Clawback Policy, adopted effective March 3, 2014 (the “Prior Policy”). Capitalized terms used in this Policy but not otherwise defined herein are defined in Section 11.

Persons Subject to Policy

This Policy shall apply to current and former Officers.

Compensation Subject to Policy

This Policy shall apply to Incentive-Based Compensation received on or after the Effective Date. For purposes of this Policy, the date on which Incentive-Based Compensation is “received” shall be determined under the Applicable Rules, which generally provide that Incentive-Based Compensation is “received” in the Company’s fiscal period during which the relevant Financial Reporting Measure is attained or satisfied, without regard to whether the grant, vesting or payment of the Incentive-Based Compensation occurs after the end of that period.

2.

Recovery of Compensation

In the event that the Company is required to prepare a Restatement, the Company shall recover, reasonably promptly and in accordance with Section 4 below, the portion of any Incentive-Based Compensation that is Erroneously Awarded Compensation, unless the Committee has determined that recovery from the relevant current or former Officer would be Impracticable. Recovery shall be required in accordance with the preceding sentence regardless of whether the applicable Officer engaged in misconduct or otherwise caused or contributed to the requirement for the Restatement and regardless of whether or when restated financial statements are filed by the Company. For clarity, the recovery of Erroneously Awarded Compensation under this Policy will not give rise to any Officer’s right to voluntarily terminate employment for “good reason” or due to a “constructive termination” (or any similar term of like effect) under any plan, program or policy of or agreement with the Company or any of its affiliates.

Manner of Recovery; Limitation on Duplicative Recovery

The Committee shall, in its sole discretion, determine the manner of recovery of any Erroneously Awarded Compensation, which may include, without limitation, reduction or cancellation by the Company or an affiliate of the Company of Incentive-Based Compensation or Erroneously Awarded Compensation, reimbursement or repayment by any person subject to this Policy of the Erroneously Awarded Compensation, and, to the extent permitted by law, an offset of the Erroneously Awarded Compensation against other compensation payable by the Company or an affiliate of the Company to such person. Notwithstanding the foregoing, unless otherwise prohibited by the Applicable Rules, to the extent this Policy provides for recovery of Erroneously Awarded Compensation already recovered by the Company pursuant to Section 304 of the Sarbanes-Oxley Act of 2002 or Other Recovery Arrangements, the amount of Erroneously Awarded Compensation already recovered by the Company from the recipient of such Erroneously Awarded Compensation may be credited to the amount of Erroneously Awarded Compensation required to be recovered pursuant to this Policy from such person.

1

Administration

This Policy shall be administered, interpreted and construed by the Committee, which is authorized to make all determinations necessary, appropriate or advisable for such purpose. The Board may re-vest in itself the authority to administer, interpret and construe this Policy in accordance with applicable law, and in such event references herein to the “Committee” shall be deemed to be references to the Board. Subject to any permitted review by the applicable national securities exchange or association pursuant to the Applicable Rules, all determinations and decisions made by the Committee pursuant to the provisions of this Policy shall be final, conclusive and binding on all persons, including the Company and its affiliates, stockholders and employees. The Committee may delegate administrative duties with respect to this Policy to one or more directors or employees of the Company, as permitted under applicable law, including any Applicable Rules.

Interpretation

This Policy shall be interpreted and applied in a manner that is consistent with the requirements of the Applicable Rules, and to the extent this Policy is inconsistent with such Applicable Rules, it shall be deemed amended to the minimum extent necessary to ensure compliance therewith.

No Indemnification; No Liability

The Company shall not indemnify or insure any person against the loss of any Erroneously Awarded Compensation pursuant to this Policy, nor shall the Company directly or indirectly pay or reimburse any person for any premiums for third-party insurance policies that such person may elect to purchase to fund such person’s potential obligations under this Policy. None of the Company, an affiliate of the Company or any member of the Committee or the Board shall have any liability to any person as a result of actions taken under this Policy.

Application; Enforceability

Effective as of the Effective Date, this Policy will supersede the Prior Policy in all respects. Except as otherwise determined by the Committee or the Board, the adoption of this Policy does not limit, and is intended to apply in addition to, any Other Recovery Arrangements. Subject to Section 4, the remedy specified in this Policy shall not be exclusive and shall be in addition to every other right or remedy at law or in equity that may be available to the Company or an affiliate of the Company or is otherwise required by applicable law and regulations.

2

Severability

The provisions in this Policy are intended to be applied to the fullest extent of the law; provided, however, to the extent that any provision of this Policy is found to be unenforceable or invalid under any applicable law, such provision will be applied to the maximum extent permitted, and shall automatically be deemed amended in a manner consistent with its objectives to the extent necessary to conform to any limitations required under applicable law.

Amendment and Termination

The Board or the Committee may amend, modify or terminate this Policy in whole or in part at any time and from time to time in its sole discretion. This Policy will terminate automatically when the Company does not have a class of securities listed on a national securities exchange or association.

Definitions

“Applicable Rules” means Section 10D of the Exchange Act, Rule 10D-1 promulgated thereunder, the listing rules of the national securities exchange or association on which the Company’s securities are listed, and any applicable rules, standards or other guidance adopted by the Securities and Exchange Commission or any national securities exchange or association on which the Company’s securities are listed.

“Board” means the Board of Directors of the Company.

“Committee” means the Compensation Committee of the Board or, in the absence of such a committee, a majority of the independent directors serving on the Board.

“Erroneously Awarded Compensation” means the amount of Incentive-Based Compensation received by a current or former Officer that exceeds the amount of Incentive-Based Compensation that would have been received by such current or former Officer based on a restated Financial Reporting Measure, as determined on a pre-tax basis in accordance with the Applicable Rules.

“Exchange Act” means the Securities Exchange Act of 1934, as amended.

“Financial Reporting Measure” means any measure determined and presented in accordance with the accounting principles used in preparing the Company’s financial statements, and any measures derived wholly or in part from such measures, including GAAP and non-GAAP financial measures, as well as stock price and total stockholder return.

“GAAP” means United States generally accepted accounting principles.

“Impracticable” means (a) the direct expense paid to third parties to assist in enforcing recovery would exceed the Erroneously Awarded Compensation; provided that the Company has (i) made reasonable attempt(s) to recover the Erroneously Awarded Compensation, (ii) documented such reasonable attempt(s), and (iii) provided such documentation to the relevant listing exchange or association, (b) the recovery would violate the Company’s home country laws adopted prior to November 28, 2022 pursuant to an opinion of home country counsel; provided that the Company has (i) obtained an opinion of home country counsel, acceptable to the relevant listing exchange or association, that recovery would result in such a violation, and (ii) provided such opinion to the relevant listing exchange or association, or (c) recovery would likely cause an otherwise tax-qualified retirement plan, under which benefits are broadly available to employees of the Company, to fail to meet the requirements of 26 U.S.C. 401(a)(13) or 26 U.S.C. 411(a) and the regulations thereunder.

3

“Incentive-Based Compensation” means, with respect to a Restatement, any compensation that is granted, earned, or vested based wholly or in part upon the attainment of one or more Financial Reporting Measures and received by a person: (a) after such person began service as an Officer; (b) who served as an Officer at any time during the performance period for that compensation; (c) while the Company has a class of securities listed on a national securities exchange or association; and (d) during the applicable Three-Year Period.

“Officer” means each person who the Company determines serves as a Company officer, as defined in Section 16 of the Exchange Act.

“Other Recovery Arrangements” means any clawback, recoupment, forfeiture or similar policies or provisions of the Company or its affiliates, including any such policies or provisions of such effect contained in any employment agreement, bonus plan, incentive plan, equity-based plan or award agreement thereunder or similar plan, program or agreement of the Company or an affiliate or required under applicable law.

“Restatement” means an accounting restatement to correct the Company’s material noncompliance with any financial reporting requirement under securities laws, including restatements that correct an error in previously issued financial statements (a) that is material to the previously issued financial statements or (b) that would result in a material misstatement if the error were corrected in the current period or left uncorrected in the current period.

“Three-Year Period” means, with respect to a Restatement, the three completed fiscal years immediately preceding the date that the Board, a committee of the Board, or the officer or officers of the Company authorized to take such action if Board action is not required, concludes, or reasonably should have concluded, that the Company is required to prepare such Restatement, or, if earlier, the date on which a court, regulator or other legally authorized body directs the Company to prepare such Restatement. The “Three-Year Period” also includes any transition period (that results from a change in the Company’s fiscal year) within or immediately following the three completed fiscal years identified in the preceding sentence. However, a transition period between the last day of the Company’s previous fiscal year end and the first day of its new fiscal year that comprises a period of nine to 12 months shall be deemed a completed fiscal year.

4

Acknowledgment and Consent toPolicy for Recovery of Erroneously Awarded Compensation

The undersigned has received a copy of the Policy for Recovery of Erroneously Awarded Compensation (the “Policy”) adopted by CoStar Group, Inc. (the “Company”), and has read and understands the Policy. Capitalized terms used but not defined herein shall have the meanings ascribed to such terms in the Policy.

As a condition of receiving Incentive-Based Compensation from the Company, the undersigned agrees that any Incentive-Based Compensation received on or after the Effective Date is subject to recovery pursuant to the terms of the Policy. To the extent the Company’s recovery right conflicts with any other contractual rights the undersigned may have with the Company, the undersigned understands that the terms of the Policy shall supersede any such contractual rights. The terms of the Policy shall apply in addition to any right of recoupment against the undersigned under applicable law and regulations.

___________________ Date	________________________________________ Signature
	________________________________________ Name
	________________________________________ Title

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Cover page - USD ($)
$ in Billions

12 Months Ended

Dec. 31, 2023

Feb. 16, 2024

Jun. 30, 2023

Cover [Abstract]

Document Type

10-K

Document Annual Report

true

Document Period End Date

Dec. 31, 2023

Current Fiscal Year End Date

--12-31

Document Transition Report

false

Entity File Number

0-24531

Entity Registrant Name

CoStar Group, Inc.

Entity Incorporation, State or Country Code

DE

Entity Tax Identification Number

52-2091509

Entity Address, Address Line One

1331 L Street, NW

Entity Address, City or Town

Washington,

Entity Address, State or Province

DC

Entity Address, Postal Zip Code

20005

City Area Code

202)

Local Phone Number

346-6500

Title of 12(b) Security

Common Stock ($0.01 par value)

Trading Symbol

CSGP

Security Exchange Name

NASDAQ

Entity Well-known Seasoned Issuer

Yes

Entity Voluntary Filers

No

Entity Current Reporting Status

Yes

Entity Interactive Data Current

Yes

Entity Filer Category

Large Accelerated Filer

Small Business Entity

false

Emerging Growth

false

ICFR Auditor Attestation Flag

true

Document Financial Statement Error Correction

false

Entity Shell Company

false

Public Float

$ 36.0

Entity Common Stock, Shares Outstanding

408,409,321

Documents Incorporated by Reference

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s definitive proxy statement, which is expected to be filed with the Securities and Exchange Commission within 120 days after the end of the registrant’s fiscal year ended December 31, 2023 are incorporated by reference into Part III of this Report.

Entity Central Index Key

0001057352

Document Fiscal Year Focus

2023

Document Fiscal Period Focus

FY

Amendment Flag

false

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Audit Information	12 Months Ended
	Dec. 31, 2023
Audit Information [Abstract]
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	Tysons, Virginia

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CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Revenues	$ 2,455.0	$ 2,182.4	$ 1,944.1
Cost of revenues	491.5	414.0	357.2
Gross profit	1,963.5	1,768.4	1,586.9
Operating expenses:
Selling and marketing (excluding customer base amortization)	989.9	684.2	622.0
Software development	267.6	220.9	201.0
General and administrative	381.5	338.7	256.8
Customer base amortization	42.2	73.6	74.8
Total operating expenses	1,681.2	1,317.4	1,154.6
Income from operations	282.3	451.0	432.3
Interest income (expense), net	213.6	32.1	(31.6)
Other income, net	5.4	3.4	3.3
Income before income taxes	501.3	486.5	404.0
Income tax expense	126.6	117.0	111.4
Net income	$ 374.7	$ 369.5	$ 292.6
Net income per share — basic (in dollars per share)	$ 0.92	$ 0.93	$ 0.75
Net income per share — diluted (in dollars per share)	$ 0.92	$ 0.93	$ 0.74
Weighted average outstanding shares — basic (in shares)	405.3	396.3	392.2
Weighted average outstanding shares — diluted (in shares)	406.9	397.8	394.2

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CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 374.7	$ 369.5	$ 292.6
Other comprehensive income (loss), net of tax
Foreign currency translation adjustment	11.5	(23.3)	(4.9)
Total other comprehensive income (loss)	11.5	(23.3)	(4.9)
Total comprehensive income	$ 386.2	$ 346.2	$ 287.7

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CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 5,215.9	$ 4,968.0
Accounts receivable	213.2	166.1
Less: Allowance for credit losses	(23.2)	(12.2)
Accounts receivable, net	190.0	153.9
Prepaid expenses and other current assets	70.2	64.0
Total current assets	5,476.1	5,185.9
Deferred income taxes, net	4.3	9.7
Property and equipment, net	472.2	321.3
Lease right-of-use assets	79.8	80.4
Goodwill	2,386.2	2,314.8
Intangible assets, net	313.7	329.3
Deferred commission costs, net	167.7	142.5
Deposits and other assets	17.7	16.6
Income tax receivable	2.0	2.0
Total assets	8,919.7	8,402.5
Current liabilities:
Accounts payable	23.1	28.6
Accrued wages and commissions	117.8	105.0
Accrued expenses	163.0	89.1
Income taxes payable	7.7	10.4
Lease liabilities	40.0	36.0
Deferred revenue	104.2	103.6
Total current liabilities	455.8	372.7
Long-term debt, net	990.5	989.2
Deferred income taxes, net	36.7	76.2
Income taxes payable	18.2	14.0
Lease and other long-term liabilities	79.9	80.4
Total liabilities	1,581.1	1,532.5
Stockholders’ equity:
Preferred stock, $0.01 par value; 2 million shares authorized; zero outstanding	0.0	0.0
Common stock, $0.01 par value; 1.2 billion shares authorized; 408.1 million and 406.7 million issued and outstanding as of December 31, 2023 and 2022, respectively	4.1	4.1
Additional paid-in capital	5,147.8	5,065.4
Accumulated other comprehensive loss	(17.6)	(29.1)
Retained earnings	2,204.3	1,829.6
Total stockholders’ equity	7,338.6	6,870.0
Total liabilities and stockholders’ equity	$ 8,919.7	$ 8,402.5

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CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par or stated value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,200,000,000	1,200,000,000
Common stock, shares issued, (in shares)	408,100,000	406,700,000
Common stock, shares outstanding (in shares)	408,100,000	406,700,000

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CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2020		394,300,000
Beginning balance at Dec. 31, 2020	$ 5,375.2	$ 3.9	$ 4,204.7	$ (0.9)	$ 1,167.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock grants surrendered	292.6				292.6
Other comprehensive (loss) income	(4.9)			(4.9)
Exercise of stock options (in shares)		200,000
Exercise of stock options	6.3		6.3
Restricted stock issued (in shares)		900,000
Restricted stock grants surrendered (in shares)		(600,000)
Restricted stock grants surrendered	(33.3)		(33.3)
Stock-based compensation expense	62.6		62.6
Employee stock purchase plan (in shares)		200,000
Employee stock purchase plan	13.0		13.0
Ending balance (in shares) at Dec. 31, 2021		395,000,000.0
Ending balance at Dec. 31, 2021	5,711.5	$ 3.9	4,253.3	(5.8)	1,460.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock grants surrendered	369.5				369.5
Other comprehensive (loss) income	(23.3)			(23.3)
Restricted stock issued (in shares)		1,500,000
Restricted stock grants surrendered (in shares)		(700,000)
Restricted stock grants surrendered	(23.1)		(23.1)
Stock-based compensation expense	$ 74.6		74.6
Employee stock purchase plan (in shares)	223,596	200,000
Employee stock purchase plan	$ 15.0		15.0
Stock issued for equity offerings, net of transaction costs (in shares)		10,700,000
Stock issued for equity offerings, net of transaction costs	745.7	$ 0.1	745.6
Ending balance (in shares) at Dec. 31, 2022		406,700,000
Ending balance at Dec. 31, 2022	6,870.0	$ 4.1	5,065.4	(29.1)	1,829.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock grants surrendered	374.7				374.7
Other comprehensive (loss) income	11.5			11.5
Exercise of stock options (in shares)		400,000
Exercise of stock options	7.5		7.5
Restricted stock issued (in shares)		1,400,000
Restricted stock grants surrendered (in shares)		(700,000)
Restricted stock grants surrendered	(23.2)		(23.2)
Stock-based compensation expense	83.6		83.6
Management stock purchase plan (in shares)		100,000
Management stock purchase plan	$ (3.2)		(3.2)
Employee stock purchase plan (in shares)	227,939	200,000
Employee stock purchase plan	$ 17.7		17.7
Ending balance (in shares) at Dec. 31, 2023		408,100,000
Ending balance at Dec. 31, 2023	$ 7,338.6	$ 4.1	$ 5,147.8	$ (17.6)	$ 2,204.3

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CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities:
Net income	$ 374.7	$ 369.5	$ 292.6
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	107.5	137.9	139.6
Amortization of deferred commissions costs	95.2	76.1	63.4
Amortization of Senior Notes discount and issuance costs	2.4	2.4	2.3
Non-cash lease expense	30.0	38.5	28.5
Stock-based compensation expense	85.0	75.2	63.7
Deferred income taxes, net	(37.2)	(31.2)	24.2
Credit loss expense	35.0	18.3	10.9
Other operating activities, net	(3.2)	(2.4)	(0.7)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(66.6)	(46.4)	(29.6)
Prepaid expenses and other current assets	(16.2)	(17.9)	(14.9)
Deferred commissions	(120.2)	(116.8)	(72.0)
Accounts payable and other liabilities	33.9	23.2	(30.2)
Lease liabilities	(39.2)	(37.4)	(30.9)
Income taxes payable, net	10.7	(19.3)	5.9
Deferred revenue	(1.3)	6.8	17.4
Other assets	(1.0)	2.2	(0.5)
Net cash provided by operating activities	489.5	478.7	469.7
Investing activities:
Proceeds from sale and settlement of investments	3.8	0.9	0.0
Proceeds from sale of property and equipment and other assets	0.0	30.1	0.6
Purchase and construction of Richmond assets	(117.5)	(35.2)	(123.7)
Purchases of property and equipment and other assets	(25.3)	(58.6)	(65.2)
Cash paid for acquisitions, net of cash acquired	(99.6)	(6.3)	(193.0)
Net cash used in investing activities	(238.6)	(69.1)	(381.3)
Financing activities:
Payments of long-term debt assumed in acquisition	0.0	(2.2)	0.0
Repurchase of restricted stock to satisfy tax withholding obligations	(26.4)	(23.0)	(33.3)
Proceeds from equity offering, net of transaction costs	0.0	745.7	0.0
Proceeds from exercise of stock options and employee stock purchase plan	23.4	13.5	18.0
Other financing activities	(0.7)	0.0	(0.4)
Net cash (used in) provided by financing activities	(3.7)	734.0	(15.7)
Effect of foreign currency exchange rates on cash and cash equivalents	0.7	(2.7)	(1.5)
Net increase in cash and cash equivalents	247.9	1,140.9	71.2
Cash and cash equivalents at beginning of year	4,968.0	3,827.1	3,755.9
Cash and cash equivalents at end of year	5,215.9	4,968.0	3,827.1
Supplemental cash flow disclosures:
Interest paid	30.7	29.9	31.5
Income taxes paid	163.2	169.2	82.1
Supplemental non-cash investing and financing activities:
Consideration owed for acquisitions	7.6	0.0	0.1
Accrued capital expenditures and non-cash landlord incentives	$ 28.9	$ 14.7	$ 2.1

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ORGANIZATION

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

ORGANIZATION

ORGANIZATION

CoStar Group (the “Company”) provides information, analytics, online marketplaces and auction services to the commercial real estate and related business community through its comprehensive, proprietary database of commercial real estate information and related tools. The Company provides online marketplaces for commercial real estate, apartment rentals, residential real estate, land for sale and businesses for sale, and its services are typically distributed to its clients under subscription-based agreements that typically renew automatically, a majority of which have a term of at least one year. The Company operates within two operating segments, North America, which includes the U.S. and Canada, and International, which primarily includes Europe, Asia-Pacific and Latin America.

The Company acquired Homes.com, BureauxLocaux, Business Immo, and OnTheMarket in May 2021, October 2021, April 2022 and December 2023, respectively. Through our Homes.com Acquisition and OnTheMarket Acquisition, we also offer online platforms that manage workflow and marketing for residential real estate agents and brokers and provide portals for homebuyers to view residential property listings. See Note 5 for further discussion of these acquisitions.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Accounting policies are consistent for each operating segment.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to revenue recognition, allowance for credit losses, the useful lives and recoverability of long-lived and intangible assets, goodwill, income taxes, accounting for business combinations, stock-based compensation, estimating the Company's incremental borrowing rate for its leases, and contingencies, among others. The Company bases these estimates on historical and anticipated results, trends and various other assumptions that it believes are reasonable, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenues and expenses. Actual results could differ from these estimates.

Revenue Recognition

The Company derives revenues primarily by (i) providing access to its proprietary database of commercial real estate information and (ii) providing online marketplaces for professional property management companies, property owners, real estate agents and brokers and landlords, in each case, typically through a fixed monthly fee for its subscription-based services. Other subscription-based services include (i) real estate and lease management solutions to commercial customers, real estate investors and lenders, (ii) access to applications to manage workflow and advertising and marketing services for residential real estate agents through its Homes.com Network and the acquisition of OnTheMarket, (iii) benchmarking and analytics for the hospitality industry and (iv) market research, portfolio and debt analysis, management and reporting capabilities.

Subscription contract rates are generally based on the number of sites, number of users, organization size, the client’s business focus, geography, the number of properties reported on or analyzed, the number and types of services to which a client subscribes, the number of properties a client advertises and the prominence and placement of a client's advertised properties in the search results. The Company’s subscription-based license agreements typically renew automatically, and a majority have a term of at least one year. Revenue from our subscription-based contracts was approximately 95%, 93% and 93% of total revenue for the years ended December 31, 2023, 2022 and 2021, respectively.

The Company also derives revenues from transaction-based services including: (i) an online auction platform for commercial real estate through Ten-X, (ii) providing online tenant applications, including background and credit checks, and rental payment processing and (iii) ancillary products and services that are sold on an ad hoc basis.

The Company analyzes contracts to determine the appropriate revenue recognition using the following steps: (i) identification of contracts with customers, (ii) identification of distinct performance obligations in the contract, (iii)

determination of contract transaction price, (iv) allocation of contract transaction price to the performance obligations and (v) determination of revenue recognition based on timing of satisfaction of the performance obligations.

The Company recognizes revenues upon the satisfaction of its performance obligation(s) (upon transfer of control of promised services to its customers) in an amount that reflects the consideration to which it expects to be entitled to in exchange for those services. Revenues from subscription-based services are recognized on a straight-line basis over the term of the agreement. Revenues from transaction-based services are recognized when the promised product or services are delivered, which, in the case of Ten-X auctions, is at the time of a successful closing for the sale of the property.

In limited circumstances, the Company's contracts with customers include promises to transfer multiple services, such as contracts for its subscription-based services and professional services. For these contracts, the Company accounts for individual performance obligations separately if they are distinct, which involves the determination of the standalone selling price for each distinct performance obligation.

Deferred revenue results from amounts billed in advance to customers or cash received from customers in advance of the Company's fulfillment of its performance obligation(s) and is recognized as those obligations are satisfied.

Contract assets represent a conditional right to consideration for satisfied performance obligations that become a receivable when the conditions are satisfied. Contract assets are generated when contractual billing schedules differ from revenue recognition timing.

Certain sales commissions are considered incremental and recoverable costs of obtaining a contract with a customer. Sales commissions incurred for obtaining new contracts are deferred and then amortized as selling and marketing expenses on a straight-line basis over a period of benefit that the Company has determined to be three years. The three-year amortization period was determined based on several factors, including the nature of the technology and proprietary data underlying the services being purchased, customer contract renewal rates and industry competition. Sales commissions that do not represent incremental costs of obtaining a contract, or that would otherwise be amortized over a period of one year or less, are not subject to capitalization.

See Note 3 for further discussion of the Company's revenue recognition.

Cost of Revenues

Cost of revenues principally consists of salaries, benefits, bonuses, stock-based compensation expenses and other indirect costs for the Company's researchers who collect and analyze the real estate data that is the basis for the Company's information, analytics and online marketplaces and for employees that support these products. Additionally, cost of revenues includes the cost of data from third-party data sources, product hosting costs, and costs related to advertising purchased on behalf of customers, credit card and other transaction fees relating to processing customer transactions, which are expensed as incurred, and the amortization of acquired trade names, technology and certain other intangible assets.

Foreign Currency Translation

The Company’s reporting currency is the U.S. dollar. The functional currency for the majority of its operations is the local currency, with the exception of certain international locations for which the functional currency is the British Pound. Assets and liabilities denominated in a foreign currency are translated into U.S. dollars using the exchange rates in effect as of the balance sheet date. Gains and losses resulting from translation are included in accumulated other comprehensive loss. Currency gains and losses on the translation of intercompany loans made to foreign subsidiaries that are of a long-term investment nature are also included in accumulated other comprehensive loss. Gains and losses resulting from transactions denominated in a currency other than the functional currency of the entity are included in other income, net in the consolidated statements of operations using the average exchange rates in effect during the period. The Company recognized net foreign currency gains of $3.0 million, $1.4 million, and a loss of $0.3 million for the years ended December 31, 2023, 2022 and 2021, respectively, which are included in other income, net on the consolidated statements of operations.

Accumulated Other Comprehensive Loss

The components of accumulated other comprehensive loss, net of tax, were as follows (in millions):

	As of December 31,
	2023		2022
Foreign currency translation loss	$	(17.6)	$	(29.1)
Total accumulated other comprehensive loss	$	(17.6)	$	(29.1)

There were no amounts reclassified out of accumulated other comprehensive loss to the consolidated statements of operations for both the years ended December 31, 2023 and 2022.

Advertising Costs

The Company expenses advertising costs as incurred. Advertising costs include digital marketing, television, radio, print and other media advertising. Advertising costs were $549.6 million, $305.7 million and $312.0 million for the years ended December 31, 2023, 2022 and 2021, respectively.

Income Taxes

Deferred income taxes result from temporary differences between the tax basis of assets and liabilities and the basis reported in the Company’s consolidated financial statements. Deferred tax liabilities and assets are determined based on the difference between the financial statement and the tax basis of assets and liabilities using enacted rates in effect during the year in which the Company expects differences to reverse. Valuation allowances are provided against assets, including net operating losses, if the Company determines it is more likely than not that some portion or all of an asset may not be realized. Interest and penalties related to income tax matters are recognized in income tax expense.

The Company has elected to record the GILTI under the current-period cost method.

See Note 12 for further discussion of income taxes.

Net Income Per Share

Net income per share is computed by dividing net income by the weighted-average number of common shares outstanding during the period on a basic and diluted basis. The Company's potentially dilutive securities include outstanding stock options, unvested stock-based awards, which include restricted stock awards that vest over a specific service period, restricted stock awards with a performance and market condition, restricted stock units and Matching RSUs awarded under the MSPP. Shares underlying unvested restricted stock awards that vest based on a performance and market condition that have not been achieved as of the end of the period are not included in the computation of basic or diluted earnings per share. Diluted net income per share considers the impact of potentially dilutive securities except when the inclusion of the potentially dilutive securities would have an anti-dilutive effect.

See Note 16 for further discussion of the Company's calculation of net income per share.

Stock-Based Compensation

Equity instruments issued in exchange for services performed by officers, employees and directors of the Company are accounted for using a fair-value based method and the fair value of such equity instruments is recognized as expense in the consolidated statements of operations.

For stock-based awards that vest over a specific service period, compensation expense is measured based on the fair value of the awards at the grant date and is recognized on a straight-line basis over the service period of the awards, net of an estimated forfeiture rate. For equity instruments that vest based on achievement of both a performance and market condition, stock-based compensation expense is recognized over the service period of the awards based on the expected achievement of the related performance conditions at the end of each reporting period. If the Company's initial estimates of the achievement of the performance conditions change, the related stock-based compensation expense may fluctuate from period to period based on those estimates. If the performance conditions are not met, no stock-based compensation expense will be recognized and any previously recognized stock-based compensation expense will be reversed. For awards with both a performance and a market condition, the Company estimates the fair value of each equity instrument granted on the date of grant using a Monte-Carlo simulation model. This pricing model uses multiple simulations to evaluate the probability of achieving the market condition to calculate the fair value of the awards which includes the recent market price and volatility of the Company's shares. When

determining the grant date fair value of all stock-based awards, the Company considers whether it is in possession of any material, non-public information that upon its release would have a material effect on its share price, and if so, whether the observable share price or expected volatility assumptions used in determining the fair value of the awards should be adjusted.

Stock-based compensation expense for stock options, restricted stock awards and restricted stock units issued under equity incentive plans, stock purchases under the ESPP, DSUs and Matching RSUs awarded under the MSPP included in the Company’s consolidated statements of operations were as follows (in millions):

	Year Ended December 31,
	2023		2022			2021
Cost of revenues	$	14.3	$	12.6		$	11.2
Selling and marketing (excluding customer base amortization)	9.1		7.8		7.8	6.3
Software development	17.5		13.0			12.5
General and administrative	44.1		41.8			33.7
Total stock-based compensation expense	$	85.0	$	75.2		$	63.7

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Cash and cash equivalents were $5.2 billion and $5.0 billion as of December 31, 2023 and 2022, respectively. The Company had no restricted cash as of December 31, 2023 and 2022.

Concentration of Credit Risk and Financial Instruments

The Company’s customer base creates a lack of dependence on any individual customer that mitigates the risk of nonpayment of the Company’s accounts receivable. No single customer accounted for more than 5% of the Company’s revenues for each of the years ended December 31, 2023, 2022 and 2021. The carrying amount of the accounts receivable approximates the net realizable value.

The Company holds cash at major financial institutions that often exceed Federal Deposit Insurance Corporation-insured limits. The Company manages its credit risk associated with cash concentrations by diversifying cash holdings across AAA rated Government and Treasury Money Market Funds and multiple high quality financial institutions, and by periodically evaluating the credit quality of the primary financial institutions holding such deposits. The carrying value of cash approximates fair value. Historically, the Company has not experienced any losses due to such cash concentrations.

Allowance for Credit Losses

The Company maintains an allowance for credit losses to cover its current expected credit losses on its trade receivables and contract assets arising from the failure of customers to make contractual payments. The Company estimates credit losses expected over the life of its trade receivables and contract assets based on historical information combined with current conditions that may affect a customer’s ability to pay and reasonable and supportable forecasts. While the Company uses various credit quality metrics, it primarily monitors collectability by reviewing the duration of collection pursuits on its delinquent trade receivables and historical write-off trends. Based on the Company’s experience, the customer's delinquency status, which is analyzed periodically, is the strongest indicator of the credit quality of the underlying trade receivables. The Company’s policy is to write-off trade receivables when they are deemed uncollectible. A majority of the Company's trade receivables are less than 365 days outstanding.

Under the CECL impairment model, the Company develops and documents its allowance for credit losses on its trade receivables based on five portfolio segments. The determination of portfolio segments is based primarily on the qualitative consideration of the nature of the Company’s business operations and the characteristics of the underlying trade receivables, as follows:

•CoStar Portfolio Segment - The CoStar portfolio segment consists of two classes of trade receivables based on geographical location: North America and International.

•Information Services Portfolio Segment - The Information Services portfolio segment consists of four classes of trade receivables: CoStar Real Estate Manager; Information Services, North America; STR, North America; and STR, International.

•Multifamily Portfolio Segment - The Multifamily portfolio segment consists of one class of trade receivables.

•LoopNet Portfolio Segment - The LoopNet portfolio segment consists of one class of trade receivables.

•Other Marketplaces Portfolio Segment - The Other Marketplaces portfolio segment consists of two classes of trade receivables: Ten-X and other marketplaces.

The majority of Residential revenue is e-commerce based and does not result in accounts receivable. Residential accounts receivable and the related allowance for credit losses are not material.

See Note 4 for further discussion of the Company’s accounting for allowance for credit losses.

Leases

The determination of whether an arrangement contains a lease and the classification of a lease, if applicable, is made at the commencement of the arrangement, at which time the Company also measures and recognizes an ROU asset, representing the Company’s right to use the underlying asset, and a lease liability, representing the Company’s obligation to make lease payments under the terms of the arrangement. For the purposes of recognizing ROU assets and lease liabilities associated with the Company’s leases, the Company has elected the practical expedient to not recognize a ROU asset or lease liability for short-term leases, which are leases with a term of 12 months or less. The lease term is defined as the noncancelable portion of the lease term, plus any periods covered by an option to extend the lease if it is reasonably certain that the option will be exercised.

In determining the amount of lease payments used in measuring ROU assets and lease liabilities, the Company has elected the practical expedient not to separate non-lease components from lease components for all classes of underlying assets. Consideration deemed part of the lease payments used to measure ROU assets and lease liabilities generally includes fixed payments and variable payments based on either an index or a rate, offset by lease incentives. Upon commencement, the initial ROU asset also includes any lease prepayments. ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The rates implicit within the Company's leases are generally not determinable. Therefore, the Company's incremental borrowing rate is used to determine the present value of lease payments. The determination of the Company’s incremental borrowing rate requires judgment and is determined at lease commencement and is subsequently reassessed upon a modification to the lease arrangement.

Lease costs related to the Company's operating leases are generally recognized as a single ratable lease cost over the lease term. ROU assets resulting from finance leases are accounted for as property and equipment, net.

See Note 7 for further discussion of the Company’s accounting for leases.

Property and Equipment, Net

Property and equipment are stated at cost, net of accumulated depreciation and amortization. All repairs and maintenance costs are expensed as incurred. Costs related to acquisition of additional aircraft components or the replacement of existing aircraft components are capitalized and depreciated over the estimated useful life of the aircraft or the added or replaced component, whichever is less. Depreciation and amortization are calculated on a straight-line basis over the following estimated useful lives of the assets:

Buildings	Twenty to thirty-nine years
Land	Indefinite
Aircrafts	Ten to twenty years
Furniture and office equipment	Five to ten years
Vehicles	Four to five years
Computer hardware and software	Three to five years
Leasehold improvements	Shorter of lease terms or useful life

Qualifying internal-use software costs incurred during the application development stage, which consist primarily of internal product development costs, are capitalized and amortized over the estimated useful life of the asset. All other costs are expensed as incurred. The Company removes fully depreciated property and equipment from the cost and accumulated depreciation amounts disclosed in the period they become fully depreciated.

In January 2021, the Company purchased an office building located in Richmond, Virginia, together with the land and assumed an existing lease for a purchase price of $131 million, inclusive of property taxes, title insurance and other transaction costs. The purchase of the Richmond building was accounted for as an asset acquisition, including an intangible asset for the assumed lease. The assumed lease terminated in the year ending December 31 2023. The net impact from the lease arrangement is recorded in other income, net on the consolidated statements of operations and was not material. The Company has broken ground on an expansion of its campus in Richmond, Virginia and acquired a small office building near the campus to facilitate employee staging while the expansion is being constructed. The capitalized spending associated with these efforts is recorded in the purchase and construction of Richmond assets line of the consolidated statements of cash flows.

Long-Lived Assets, Intangible Assets and Goodwill

Long-lived assets, such as property and equipment, and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company capitalizes interest on borrowings during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying asset and amortized over the estimated useful life of the asset. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset or asset group. If the carrying amount of an asset exceeds its estimated undiscounted future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset.

During 2022, the Company ceased using leased properties in California and Maryland as part of efforts to centralize its workforce, which resulted in an impairment charge of $9 million for lease ROU assets and property and equipment related to abandoned leases. The impairment was recorded in the general and administrative expense line of the consolidated statements of operations. The leases related to the North America segment.

Acquired technology and data, customer base assets, trade names and other intangible assets are related to the Company’s acquisitions. Acquired technology and data is amortized on a straight-line basis over periods ranging from 2 years to 7 years. Acquired intangible assets characterized as customer base assets consist of acquired customer contracts and the related customer relationships and are amortized over periods ranging from 3 years to 13 years. Acquired customer bases are amortized on an accelerated or straight-line basis depending on the expected economic benefit of the intangible asset. Acquired trade names and other intangible assets are amortized on a straight-line basis over periods ranging from 3 years to 15 years. The Company removes fully amortized intangible assets from the cost and accumulated amortization amounts disclosed.

Goodwill represents the future economic benefits arising from a business combination and is calculated as the excess of the purchase consideration paid in a business combination over the fair value of the net identifiable assets acquired. Goodwill is not amortized, but instead is assigned to each of the Company's reporting units and tested for impairment at least annually, on October 1, or more frequently if an event or other circumstance indicates that the fair value of a reporting unit may be below its carrying amount. The Company may first assess qualitative factors to evaluate whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or elect to bypass the qualitative assessment. If it is determined that it is more likely than not that the fair value of a reporting unit is less than its carrying value, or the Company elects to bypass the qualitative assessment, the Company then performs a quantitative assessment by determining the fair value of each reporting unit. The estimate of the fair value of each reporting unit is based on a projected discounted cash flow model that includes significant assumptions and estimates including the discount rate, growth rate and future financial performance. Assumptions about the discount rate are based on a weighted average cost of capital for comparable companies. Assumptions about the growth rate and future financial performance of a reporting unit are based on the Company's forecasts, business plans, economic projections and anticipated future cash flows. The fair value of each reporting unit is compared to the carrying amount of the reporting unit. If the carrying value of the reporting unit exceeds the fair value, then an impairment loss is recognized for the difference.

See Notes 5, 9 and 10 for further discussion of acquisitions, goodwill and intangible assets, respectively.

Debt Issuance Costs

Costs incurred in connection with the issuance of long-term debt are deferred and amortized as interest expense over the term of the related debt using the effective interest method for term debt and on a straight-line basis for revolving debt. The Company made a policy election to classify deferred issuance costs on the revolving credit facility as a long-term asset on its consolidated balance sheets. Upon a refinancing or amendment, previously capitalized debt issuance costs are expensed and included in loss on extinguishment of debt if the Company determines that there has been a substantial modification of the related debt. If the Company determines that there has not been a substantial modification of the related debt, any previously capitalized debt issuance costs are amortized as interest expense over the term of the new debt instrument.

See Note 11 for further discussion of the Company's accounting for its outstanding debt, revolving credit facility and related issuance costs.

Business Combinations

The Company includes the results of operations of the businesses that it acquires from the date of acquisition. The Company generally allocates the purchase consideration to the tangible assets acquired and liabilities assumed and intangible assets acquired based on their estimated fair values on the date of the acquisition. The purchase price is generally determined based on the fair value of the assets transferred, liabilities assumed and equity interests issued, after considering any transactions that are separate from the business combination. The excess of the fair value of purchase consideration over the fair values of these identifiable assets and liabilities is recorded as goodwill. The Company applies significant assumptions, estimates and judgments in determining the fair value of assets acquired and liabilities assumed on the acquisition date, especially with respect to intangible assets and contingent liabilities. Significant estimates in valuing certain intangible assets include, but are not limited to, future expected cash flows from acquired customer bases, acquired technology and acquired trade names, useful lives, royalty rates and discount rates. Estimates of fair value are based on assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. Any adjustments to provisional amounts that are identified during the measurement period, not to exceed one year from the date of acquisition, are recorded in the reporting period in which the adjustment amounts are determined. Upon the conclusion of the measurement period, any subsequent adjustments are recorded to earnings.

For a given acquisition, the Company may identify certain pre-acquisition contingencies as of the acquisition date and may extend its review and evaluation of these pre-acquisition contingencies throughout the measurement period in order to obtain sufficient information to assess whether the Company includes these contingencies as a part of the fair value estimates of assets acquired and liabilities assumed and, if so, to determine their estimated amounts.

If the Company cannot reasonably determine the fair value of a pre-acquisition contingency (non-income tax related) by the end of the measurement period, which is generally the case given the nature of such matters, the Company will recognize an asset or a liability for such pre-acquisition contingency if: (i) it is probable that an asset existed or a liability had been assumed at the acquisition date and (ii) the amount of the asset or liability can be reasonably estimated. Subsequent to the measurement period, changes in the Company's estimates of such contingencies will affect earnings and could have a material effect on its results of operations and financial position.

In addition, uncertain tax positions and tax-related valuation allowances assumed in connection with a business combination are initially estimated as of the acquisition date. The Company reevaluates these items based upon facts and circumstances that existed as of the acquisition date with any adjustments to its preliminary estimates being recorded to goodwill, provided that the Company is within the measurement period. Subsequent to the measurement period, changes to these uncertain tax positions and tax-related valuation allowances will affect the Company's provision for income taxes in its consolidated statements of operations and comprehensive income and could have a material impact on its results of operations and financial position.

Transaction costs associated with business combinations are expensed as incurred, and are included in general and administrative expenses in the consolidated statements of operations.

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In 2021, the Company adopted ASU 2021-08, Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. This guidance requires contract assets and liabilities acquired or assumed in an acquisition be measured in accordance with the accounting framework for revenue from contracts with customers as if the

Company had originated the acquired contract. This is an exception to the general requirement to measure assets acquired and liabilities assumed at their fair value on the acquisition date. The Company applied this revised guidance to all acquisitions in the year ended December 31, 2021. The application of this guidance to contract assets and contract liabilities acquired or assumed in connection with the Company's acquisitions for the year ended December 31, 2021 did not have a material impact on the Company's consolidated financial statements and related disclosures.

In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASC 848 contains optional expedients and exceptions for applying GAAP to debt, contracts, hedging relationships and other transactions affected by reference rate reform. The provisions of ASC 848 must be applied to all contracts that are accounted for under a Topic, Subtopic or Industry Subtopic for all transactions other than derivatives, which may be applied at a hedging relationship level. Originally, the guidance was effective for fiscal years beginning after January 1, 2021, including interim periods within those fiscal years. However, in response to the deferral of the cessation date for certain overnight LIBOR measures, the FASB issued ASU 2022-06 on December 21, 2022, which extends the sunset date of Topic 848 to December 31, 2024. The Company's 2020 Credit Agreement provides for a $750 million revolving credit facility and a letter of credit sublimit of $20 million, with interest rates previously benchmarked to LIBOR. The Company adopted this accounting pronouncement with the execution of the First Amendment to the 2020 Credit Agreement in May 2023. This guidance provides an optional practical expedient that allows a qualifying modification to be accounted for as a debt modification rather than be analyzed under existing guidance to determine if the modification should be accounted for as a debt extinguishment. In adopting this accounting standard, we have elected to apply this optional expedient. Adopting this accounting standard did not have a material impact on the Company's consolidated financial statements and related disclosures.

Recent Accounting Pronouncements Not Yet Adopted

In March 2022, the FASB issued ASU 2022-02, Financial Instruments-Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures. This ASU eliminates prior guidance on troubled debt restructurings for creditors that have adopted ASU 2016-13, Measurement of Credit Losses in Financial Statements, and adds enhanced disclosures for creditors with respect to loan refinancings and restructurings for borrowers experiencing financial difficulty. In addition, the ASU amends guidance on "vintage disclosures" to require the disclosure of current period gross write offs by year of origination. This guidance is effective for fiscal years beginning after December 15, 2022. The Company expects there to be no material impact on its consolidated financial statements and related disclosures from the adoption of this ASU.

In November 2023, the FASB issued ASU No. 2023-07 (Topic 280), Improvements to Reportable Segment Disclosures. The ASU primarily will require enhanced disclosures about significant segment expenses. Additionally, it requires disclosure of the title and position of the individual identified as the CODM and an explanation of how the CODM uses the reported measures of a segment’s profit or loss in assessing segment performance and deciding how to allocate resources. The ASU is effective for annual periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Adoption of the ASU should be applied retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures.

In December 2023, the FASB issued ASU No. 2023-09 (Topic 740), Improvements to Income Tax Disclosures (Topic 740). The ASU requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as an expansion of other income tax disclosures. The ASU is effective on a prospective basis for annual reporting periods beginning after December 15, 2024. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures.

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REVENUE FROM CONTRACTS WITH CUSTOMERS

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

REVENUE FROM CONTRACTS WITH CUSTOMERS

REVENUE FROM CONTRACTS WITH CUSTOMERS

Disaggregated Revenue

The Company provides information, analytics and online marketplaces to the commercial real estate industry, hospitality industry, residential industry and related professionals. Revenues by operating segment and type of service consist of the following (in millions):

	Year Ended December 31,
	2023						2022						2021
	North America		International		Total		North America		International		Total		North America		International		Total
CoStar	$	886.0	$	39.2	$	925.2	$	800.2	$	36.8	$	837.0	$	686.9	$	35.9	$	722.8
Information services	132.4		38.5		170.9		125.0		32.4		157.4		113.8		27.9		141.7
Multifamily	914.2		—		914.2		745.4		—		745.4		678.7		—		678.7
LoopNet	255.4		9.4		264.8		223.7		7.2		230.9		204.8		2.7		207.5
Residential	43.9		2.2		46.1		73.7		—		73.7		74.6		—		74.6
Other Marketplaces	133.8		—		133.8		138.0		—		138.0		118.8		—		118.8
Total revenues	$	2,365.7	$	89.3	$	2,455.0	$	2,106.0	$	76.4	$	2,182.4	$	1,877.6	$	66.5	$	1,944.1

Deferred Revenue

Deferred revenue as of December 31, 2023 and 2022 was as follows (in millions):

		December 31,
Balance	Balance Sheet Caption	2023		2022
Current portion	Deferred revenue	$	104.2	$	103.6
Non-current portion	Lease and other long-term liabilities	0.1		0.2
Total deferred revenue		$	104.3	$	103.8

Changes in deferred revenue for the period were as follows (in millions):

Balance at December 31, 2022(1)	$	103.8
Revenue recognized in the current period from the amounts in the beginning balance	(103.8)
New deferrals, net of amounts recognized in the current period	103.4
Effects of foreign currency	0.9
Balance at December 31, 2023(2)	$	104.3
__________________________

(1) This balance includes $1.8 million of net new deferrals recognized in connection with business acquisitions made in 2022. See Note 5 for further discussion of acquisitions.

(2) This balance includes $1.0 million of net new deferrals recognized in connection with business acquisitions made in 2023. See Note 5 for further discussion of acquisitions.

Contract Assets

Contract assets are generated when contractual billing schedules differ from revenue recognition timing and represent a conditional right to consideration for satisfied performance obligations that becomes a receivable when the conditions are satisfied. Contract assets as of December 31, 2023 and 2022 were as follows (in millions):

		December 31,
Balance	Balance Sheet Caption	2023		2022
Current portion	Prepaid expenses and other current assets	$	5.8	$	4.0
Non-current portion	Deposits and other assets	8.0		8.4
Total contract assets		$	13.8	$	12.4

Revenue recognized from contract assets for the years ended December 31, 2023 and 2022 were $1.4 million and $3.2 million, respectively.

Commissions

Commissions expense is included in selling and marketing expense in the Company's consolidated statements of operations. The Company determined that no deferred commissions were impaired as of both December 31, 2023 and 2022. Commissions expense activity for the years ended December 31, 2023, 2022 and 2021, was as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Commissions incurred	$	173.5	$	162.1	$	117.3
Commissions capitalized in the current period	(120.2)		(116.8)		(72.0)
Amortization of deferred commissions costs	95.2		76.1		63.4
Total commissions expense	$	148.5	$	121.4	$	108.7

See Note 2 for the Company's policy on accounting for commissions.

Unsatisfied Performance Obligations

Remaining contract consideration for which revenue had not been recognized due to unsatisfied performance obligations was $409.6 million as of December 31, 2023, which the Company expects to recognize over the next five years. This amount does not include contract consideration for contracts with a duration of one year or less.

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ALLOWANCE FOR CREDIT LOSSES

12 Months Ended

Dec. 31, 2023

Credit Loss [Abstract]

ALLOWANCE FOR CREDIT LOSSES

ALLOWANCE FOR CREDIT LOSSES

The following tables detail the activity related to the allowance for credit losses for trade receivables by portfolio segment (in millions):

	Year Ended December 31, 2023
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2022	$	4.5	$	1.1	$	4.3	$	1.4	$	0.9	$	12.2
Current-period provision (release) for expected credit losses	22.1		1.4		4.9		6.0		0.6		35.0
Write-offs charged against the allowance, net of recoveries and other	(16.9)		—		(1.9)		(4.7)		(0.5)		(24.0)
Ending balance at December 31, 2023	$	9.7	$	2.5	$	7.3	$	2.7	$	1.0	$	23.2

-

	Year Ended December 31, 2022
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2021	$	5.4	$	1.8	$	3.4	$	2.0	$	0.8	$	13.4
Current-period provision (release) for expected credit losses	9.2		(0.6)		5.8		3.8		0.1		18.3
Write-offs charged against the allowance, net of recoveries and other	(10.1)		(0.1)		(4.9)		(4.4)		—		(19.5)
Ending balance at December 31, 2022	$	4.5	$	1.1	$	4.3	$	1.4	$	0.9	$	12.2

	Year Ended December 31, 2021
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2020	$	5.6	$	2.7	$	4.4	$	1.7	$	0.8	$	15.2
Current-period provision for expected credit losses	5.6		(0.4)		3.1		2.6		—		10.9
Write-offs charged against the allowance, net of recoveries and other	(5.8)		(0.5)		(4.1)		(2.3)		—		(12.7)
Ending balance at December 31, 2021	$	5.4	$	1.8	$	3.4	$	2.0	$	0.8	$	13.4

Credit loss expense is included in general and administrative expenses on the consolidated statements of operations. Credit loss expense related to contract assets was not material for the years ended December 31, 2023, 2022 and 2021. The majority of the Residential portfolio segment revenue is e-commerce based and does not result in accounts receivable.

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ACQUISITIONS

12 Months Ended

Dec. 31, 2023

Business Combination and Asset Acquisition [Abstract]

ACQUISITIONS

ACQUISITIONS

OnTheMarket

On December 12, 2023, CoStar UK acquired OnTheMarket, the operator of onthemarket.com, a U.K. residential property portal. At the time of closing, CoStar UK acquired all of the then issued ordinary share capital of OnTheMarket for cash consideration of 110 pence per share or £94.0 million ($117.9 million). OnTheMarket had certain share option contracts that had not been exercised at the time of closing for which CoStar UK has established a liability for £2.0 million ($2.6 million). This resulted in total consideration of £96.0 million ($120.4 million). Certain shares outstanding at the time of the closing resulted from contracts held by employees of OnTheMarket or its subsidiaries that required OnTheMarket to withhold income and employment taxes of £4.0 million ($5.1 million) which represented consideration payable at December 31, 2023 and were remitted in January 2024.

The following table summarized the amounts recorded for acquired assets and assumed liabilities recorded at their fair value as of the closing date of the acquisition (in millions):

	Preliminary: December 12, 2023
Cash and cash equivalents	$	18.2
Accounts receivable	2.3
Goodwill	62.8
Intangible assets	55.2
Accrued expenses	(12.7)
Accrued wages and commissions	(2.0)
Deferred income taxes, net	(3.0)
Other assets and liabilities	(0.4)
Fair value of identifiable net assets acquired	$	120.4

The net assets of OnTheMarket were recorded at their estimated fair values. In valuing the acquired assets and assumed liabilities, fair value estimates were based primarily on future expected cash flows, market rate assumptions for contractual obligations and appropriate discount rates. The purchase price allocation is preliminary, subject primarily to the Company's assessment of certain tax matters, contingencies and intangibles valuation. The estimated fair value of the customer base assets incorporated significant assumptions that had a material impact on the estimated fair value, such as discount rates, projected revenue growth rates, customer attrition rates and profit margins.

The following table summarizes the fair values (in millions) of the identifiable intangible assets acquired in the OnTheMarket Acquisition included in the Company's International operating segment, their related estimated useful lives (in years) and their respective amortization methods:

	Estimated Fair Value		Estimated Useful Life	Amortization Method
Customer base	$	42.0	8	Accelerated
Trade name	10.2		15	Straight-line
Technology	3.0		2	Straight-line
Total intangible assets	$	55.2

Goodwill is calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. Specifically, the goodwill recorded as part of the OnTheMarket Acquisition includes, but is not limited to: (i) the expected synergies and other benefits that the Company believes will result from combining its operations with international operations and (ii) any intangible assets that do not qualify for separate recognition, such as the assembled workforce. The $62.8 million of goodwill recorded as part of the acquisition is associated with the Company's International operating segment, of which none is expected to be deductible for income tax purposes. Transaction costs associated with the OnTheMarket Acquisition were $11.0 million.

Business Immo

In April 2022, the Company acquired Business Immo, a leading commercial real estate news service provider in France, for €5.8 million ($6.3 million), net of cash acquired and the assumption of outstanding debt. As part of the acquisition, the Company recorded goodwill and intangible assets of $7.1 million and $3.9 million, respectively. The net assets of Business Immo were recorded at their estimated fair value. The Company retired the assumed debt in the second quarter of 2022. The net assets of Business Immo were recorded at their estimated fair value. The Company retired the assumed debt in the second quarter of 2022.

BureauxLocaux

In October 2021, CoStar UK acquired BureauxLocaux, a commercial real estate digital marketplace in France, for a base purchase price of €35.0 million ($40.6 million) in cash, subject to customary working capital and other post-closing adjustments which were settled in the fourth quarter of 2021. As part of the acquisition, the Company recorded goodwill and intangible assets of $27.4 million and $18.3 million, respectively, in the Company's International operating segment. The net assets of BureauxLocaux were recorded at their estimated fair value.

Homes.com

In May 2021, the Company closed the Homes.com Acquisition, in which the Company acquired all of the issued and outstanding equity interests in Homes Group for a purchase price of $150.0 million in cash, subject to customary working capital and other post-closing adjustments which resulted in total consideration of $152.2 million. Homes Group operates Homes.com, a residential marketplace hosted on the website Homes.com and mobile apps that provided real estate advertising and marketing services. In November 2022 CoStar Group integrated the operations of Homes.com and Homesnap.

The following table summarizes the amounts recorded for acquired assets and assumed liabilities recorded at their fair values as of the acquisition date (in millions):

	Final: May 24, 2021
Cash and cash equivalents	$	—
Accounts receivable	1.8
Lease right-of-use assets	0.4
Goodwill	91.9
Intangible assets	53.4
Deferred income taxes, net	7.9
Lease liabilities	(0.4)
Deferred revenue	(1.5)
Other assets and liabilities	(1.3)
Fair value of identifiable net assets acquired	$	152.2

The net assets of Homes Group were recorded at their estimated fair values. In valuing the acquired assets and assumed liabilities, fair value estimates were based primarily on future expected cash flows, market rate assumptions for contractual obligations and appropriate discount rates. The estimated fair value of the customer base assets incorporated significant assumptions that had a material impact on the estimated fair value, such as discount rates, projected revenue growth rates, customer attrition rates and profit margins.

The following table summarizes the fair values (in millions) of the identifiable intangible assets acquired in the Homes.com Acquisition included in the Company's North America operating segment, their related estimated useful lives (in years) and their respective amortization methods:

	Estimated Fair Value		Estimated Useful Life	Amortization Method
Customer base	$	32.0	8	Accelerated
Trade name	21.0		15	Straight-line
Technology	0.4		2	Straight-line
Total intangible assets	$	53.4

Goodwill is calculated as the excess of the consideration transferred over the net assets recognized and represents the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. Specifically, the goodwill recorded as part of the Homes.com Acquisition includes but is not limited to: (i) the expected synergies and other benefits that the Company believes will result from combining its operations with Homes.com operations and (ii) any intangible assets that do not qualify for separate recognition, such as the assembled workforce. The $91.9 million of goodwill recorded as part of the acquisition is associated with the Company's North America operating segment, of which $20.0 million is expected to be deductible for income tax purposes.

Transaction costs associated with the Homes.com Acquisition were not material. The Company paid $5.0 million into a cash escrow account for stay bonuses for certain Homes.com employees and recognized compensation expense for the stay bonus over the six-month post-combination period. Upon acquisition, the Company assessed the probability it would be required to pay certain state tax liabilities and recorded an accrual of $6.6 million determined in accordance with the provisions of ASC 450, Contingencies, as the fair value was not determinable. Landmark has agreed to indemnify the Company for tax liabilities related to periods prior to the acquisition and an indemnification asset was established for $6.6 million in the purchase price allocation.

Pro Forma Financial Information (unaudited)

The unaudited pro forma financial information presented below reflects the consolidated results of operations of the Company assuming the OnTheMarket Acquisition had taken place on January 1, 2022 and was as follows (in millions, except per share data):

	Year Ended December 31,
	2023		2022
Revenue	$	2,494.0	$	2,224.3
Net income	$	371.9	$	361.9
Net income per share - basic	$	0.91	$	0.91
Net income per share - diluted	$	0.91	$	0.91

The impact of the OnTheMarket Acquisition on the Company's revenue and net income in the consolidated statements of operations from December 12, 2023 through December 31, 2023 was not material.

The unaudited pro forma financial information presented below reflects the consolidated results of operations of the Company assuming the Homes.com Acquisition had taken place on January 1, 2020 and was as follows (in millions, except per share data):

	Year Ended December 31,
	2021
Revenue	$	1,962.1
Net income	$	286.7
Net income per share - basic	$	0.74
Net income per share - diluted	$	0.73

The unaudited pro forma financial information for all periods presented includes amortization charges from acquired intangible assets, retention compensation, as referenced above, and the related tax effects, along with certain other accounting effects, but excludes the impacts of any expected operational synergies. The unaudited pro forma financial information, as presented above, is for informational purposes only and is not necessarily indicative of the results of operations that would have been achieved if the acquisitions had not taken on place on the dates listed above.

The impact of the Homes.com Acquisition on the Company's revenues and net income in the consolidated statements of operations from May 24, 2021 through December 31, 2021 was an increase of $13.6 million and a decrease of $23.5 million, respectively.

The pro forma financial information of the BureauxLocaux Acquisition and Business Immo Acquisition was not material.

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INVESTMENTS AND FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2023

Investments And Fair Value Disclosures [Abstract]

INVESTMENTS AND FAIR VALUE MEASUREMENTS

INVESTMENTS AND FAIR VALUE MEASUREMENTS

Fair value is defined as the price that would be received in the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. There is a three-tier fair value hierarchy, which categorizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs for which little or no market data exists, therefore requiring an entity to develop its own assumptions.

The Company's financial assets comprise Level 1 cash equivalents with original maturities of three months or less in the amount of $5.1 billion and $4.8 billion as of December 31, 2023 and 2022, respectively. The Company had no Level 2 or Level 3 financial assets measured at fair value.

The Company holds other financial instruments, including cash deposits, accounts receivable, accounts payable, accrued expenses and Senior Notes. The carrying value for such financial instruments, other than the Senior Notes, each approximated their fair values as of December 31, 2023 and 2022. The estimated fair value of the Company's outstanding Senior Notes using quoted prices from the over-the-counter markets, considered Level 2 inputs, was $0.9 billion and $0.8 billion as of December 31, 2023 and 2022, respectively.

INVESTMENTS AND FAIR VALUE MEASUREMENTS

INVESTMENTS AND FAIR VALUE MEASUREMENTS

Fair value is defined as the price that would be received in the sale of an asset or paid to transfer a liability in an orderly transaction between market participants. There is a three-tier fair value hierarchy, which categorizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs for which little or no market data exists, therefore requiring an entity to develop its own assumptions.

The Company's financial assets comprise Level 1 cash equivalents with original maturities of three months or less in the amount of $5.1 billion and $4.8 billion as of December 31, 2023 and 2022, respectively. The Company had no Level 2 or Level 3 financial assets measured at fair value.

The Company holds other financial instruments, including cash deposits, accounts receivable, accounts payable, accrued expenses and Senior Notes. The carrying value for such financial instruments, other than the Senior Notes, each approximated their fair values as of December 31, 2023 and 2022. The estimated fair value of the Company's outstanding Senior Notes using quoted prices from the over-the-counter markets, considered Level 2 inputs, was $0.9 billion and $0.8 billion as of December 31, 2023 and 2022, respectively.

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LEASES

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

LEASES

LEASES

The Company has operating and finance leases for its office facilities, data centers, and vehicles. The Company's leases have remaining terms up to eight years. The leases contain various renewal and termination options. The period that is subject to an option to extend the lease is included in the lease term if it is reasonably certain that the option will be exercised. The period that is subject to an option to terminate the lease is included if it is reasonably certain that the option will not be exercised.

Lease costs related to the Company's operating and finance leases included in the consolidated statements of operations were as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Operating lease costs:
Cost of revenues	$	10.0	$	8.4	$	10.1
Software development	6.3		7.2		6.9
Selling and marketing (excluding customer base amortization)	15.4		12.6		11.9
General and administrative	4.0		5.4		5.9
Total operating lease costs	35.7		33.6		34.8
Finance lease costs:
Amortization of ROU assets	0.8		—		—
Interest on lease liabilities	0.2		—		—
Total finance lease costs	1.0		—		—
Total lease costs	$	36.7	$	33.6	$	34.8

Finance lease costs primarily relate to vehicles used by the Company's research teams, and the amortization of the ROU assets are recorded to cost of revenue in the consolidated statements of operations. The impact of lease costs related to short-term leases was not material for the years ended December 31, 2023, 2022 and 2021.

Supplemental balance sheet information related to operating leases was as follows ($ in millions):

		Year Ended December 31,
Balance	Balance Sheet Location	2023			2022
Operating lease liabilities		$	109.9		$	118.3
Less: imputed interest		(7.0)			(6.2)
Present value of lease liabilities		102.9			112.1
Less: current portion of lease liabilities	Lease liabilities	36.9			36.0
Long-term lease liabilities	Lease and other long-term liabilities	$	66.0		$	76.1
Weighted-average remaining lease term in years		3.9			3.6
Weighted-average discount rate		3.6		%	3.1		%
ROU Assets	Lease right-of-use assets	$	79.8		$	80.4
Finance lease liabilities		$	14.6		$	—
Less: imputed interest		(1.6)			—
Present value of lease liabilities		13.0			—
Less: current portion of lease liabilities	Lease liabilities	3.1			—
Long-term lease liabilities	Lease and other long-term liabilities	$	9.9		$	—
Weighted-average remaining lease term in years		3.8			0
Weighted-average discount rate		7.8		%	—		%
ROU Assets	Property and equipment, net	$	10.8		$	—

Supplemental cash flow information related to leases was as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used in operating leases	$	44.9	$	41.6	$	37.3
Operating cash flows used in finance leases	$	0.2	$	—	$	—
Financing cash flows used in finance leases	$	0.7	$	—	$	—
ROU assets obtained in exchange for lease new obligations:
Operating leases	$	29.1	$	20.0	$	34.2
Finance leases	$	13.6	$	—	$	—

LEASES

LEASES

The Company has operating and finance leases for its office facilities, data centers, and vehicles. The Company's leases have remaining terms up to eight years. The leases contain various renewal and termination options. The period that is subject to an option to extend the lease is included in the lease term if it is reasonably certain that the option will be exercised. The period that is subject to an option to terminate the lease is included if it is reasonably certain that the option will not be exercised.

Lease costs related to the Company's operating and finance leases included in the consolidated statements of operations were as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Operating lease costs:
Cost of revenues	$	10.0	$	8.4	$	10.1
Software development	6.3		7.2		6.9
Selling and marketing (excluding customer base amortization)	15.4		12.6		11.9
General and administrative	4.0		5.4		5.9
Total operating lease costs	35.7		33.6		34.8
Finance lease costs:
Amortization of ROU assets	0.8		—		—
Interest on lease liabilities	0.2		—		—
Total finance lease costs	1.0		—		—
Total lease costs	$	36.7	$	33.6	$	34.8

Finance lease costs primarily relate to vehicles used by the Company's research teams, and the amortization of the ROU assets are recorded to cost of revenue in the consolidated statements of operations. The impact of lease costs related to short-term leases was not material for the years ended December 31, 2023, 2022 and 2021.

Supplemental balance sheet information related to operating leases was as follows ($ in millions):

		Year Ended December 31,
Balance	Balance Sheet Location	2023			2022
Operating lease liabilities		$	109.9		$	118.3
Less: imputed interest		(7.0)			(6.2)
Present value of lease liabilities		102.9			112.1
Less: current portion of lease liabilities	Lease liabilities	36.9			36.0
Long-term lease liabilities	Lease and other long-term liabilities	$	66.0		$	76.1
Weighted-average remaining lease term in years		3.9			3.6
Weighted-average discount rate		3.6		%	3.1		%
ROU Assets	Lease right-of-use assets	$	79.8		$	80.4
Finance lease liabilities		$	14.6		$	—
Less: imputed interest		(1.6)			—
Present value of lease liabilities		13.0			—
Less: current portion of lease liabilities	Lease liabilities	3.1			—
Long-term lease liabilities	Lease and other long-term liabilities	$	9.9		$	—
Weighted-average remaining lease term in years		3.8			0
Weighted-average discount rate		7.8		%	—		%
ROU Assets	Property and equipment, net	$	10.8		$	—

Supplemental cash flow information related to leases was as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used in operating leases	$	44.9	$	41.6	$	37.3
Operating cash flows used in finance leases	$	0.2	$	—	$	—
Financing cash flows used in finance leases	$	0.7	$	—	$	—
ROU assets obtained in exchange for lease new obligations:
Operating leases	$	29.1	$	20.0	$	34.2
Finance leases	$	13.6	$	—	$	—

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PROPERTY AND EQUIPMENT

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT

Property and equipment consists of the following (in millions):

	December 31,
	2023		2022
Leasehold improvements	$	87.8	$	108.9
Furniture, office equipment and vehicles	73.4		52.6
Computer hardware and software	56.3		43.8
Aircrafts	44.2		44.2
Land	52.2		52.2
Buildings	263.8		105.1
Property and equipment, gross	577.7		406.8
Accumulated depreciation and amortization	(105.5)		(85.5)
Property and equipment, net	$	472.2	$	321.3

Costs capitalized in connection with the expansion of our Richmond, Virginia campus were included in Buildings in the above table as of December 31, 2023. Depreciation expense for property and equipment was approximately $33.8 million, $29.1 million and $29.0 million, for the years ended December 31, 2023, 2022 and 2021, respectively. For the years ended December 31, 2023 and 2022, the Company removed $14.1 million and $27.6 million, respectively, of property and equipment that was fully depreciated from property and equipment, gross and accumulated depreciation and amortization, which had no net impact on the Company's financial results.

In August 2022, the Company entered into an agreement to sell an aircraft subject to customary condition and inspection terms. The sale of the aircraft closed in October 2022 for cash consideration of $24.9 million. The Company recorded a gain on the sale of the aircraft of $3.3 million, which was recorded to general and administrative expenses in the consolidated statements of operations. The aircraft related to the North America segment.

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GOODWILL

12 Months Ended

Dec. 31, 2023

Goodwill [Abstract]

GOODWILL

GOODWILL

The changes in the carrying amount of goodwill by operating segment consist of the following (in millions):

	North America		International		Total
Goodwill, December 31, 2021	$	2,145.8	$	175.2	$	2,321.0
Acquisitions, including measurement period adjustments(1)	3.4		7.1		10.5
Effect of foreign currency translation	—		(16.7)		(16.7)
Goodwill, December 31, 2022	2,149.2		165.6		2,314.8
Acquisitions, including measurement period adjustments	—		62.8		62.8
Effect of foreign currency translation	—		8.6		8.6
Goodwill, December 31, 2023	$	2,149.2	$	237.0	$	2,386.2
__________________________

(1) North America goodwill recorded during the year ended December 31, 2022 relates to a measurement period adjustment for income taxes for Homes.com of $3.4 million. International goodwill recorded in connection with the Business Immo Acquisition was $7.1 million.

(2) International goodwill generated during the year ended December 31, 2023 from the OnTheMarket Acquisition was $62.8 million.

Goodwill generated from acquisitions completed in 2023 and 2022 was not deductible for tax purposes.

No impairments of the Company's goodwill were recognized during each of the years ended December 31, 2023, 2022 and 2021.

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INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2023

Intangible Assets, Net (Excluding Goodwill) [Abstract]

INTANGIBLE ASSETS

INTANGIBLE ASSETS

Intangible assets consist of the following (in millions, except amortization period data):

	December 31,				Weighted- Average Amortization Period (in years)
	2023		2022
Acquired technology and data	$	36.3	$	40.4	5
Accumulated amortization	(21.0)		(20.7)
Acquired technology and data, net	15.3		19.7
Acquired customer base	509.5		464.2		10
Accumulated amortization	(330.7)		(287.0)
Acquired customer base, net	178.8		177.2
Acquired trade names and other intangible assets	258.9		247.4		13
Accumulated amortization	(139.3)		(115.0)
Acquired trade names and other intangible assets, net	119.6		132.4
Intangible assets, net	$	313.7	$	329.3

Amortization expense for intangible assets was approximately $73.7 million, $102.6 million and $103.6 million for the years ended December 31, 2023, 2022 and 2021, respectively. For the years ended December 31, 2023, 2022 and 2021, the Company removed $7.4 million, $87.7 million, and $171.0 million, respectively, of intangible assets that were fully amortized from the acquired intangible assets and accumulated amortization, which had no net impact on the Company's financial results.

In the aggregate, the Company expects the future amortization expense for intangible assets existing as of December 31, 2023 to be approximately $70.8 million, $54.8 million, $43.3 million, $34.7 million and $30.8 million for the years ending December 31, 2024, 2025, 2026, 2027 and 2028, respectively.

Intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. No impairments of the Company's intangible assets were recognized during each of the years ended December 31, 2023, 2022 and 2021. The Company decided to eliminate usage fees related to agent access to a Homesnap product charged to a specific customer class. This resulted in an acceleration of $16.3 million of amortization expense in 2022 for acquired customer base for this customer class.

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LONG-TERM DEBT

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

LONG-TERM DEBT

LONG-TERM DEBT

The table below presents the components of outstanding debt (in millions):

	December 31,
	2023		2022
2.800% Senior Notes due July 15, 2030	$	1,000.0	$	1,000.0
2020 Credit Agreement, due July 1, 2025	—		—
Total face amount of long-term debt	1,000.0		1,000.0
Senior Notes unamortized discount and issuance costs	(9.5)		(10.8)
Long-term debt, net	$	990.5	$	989.2

Senior Notes

On July 1, 2020, the Company issued $1.0 billion aggregate principal amount of 2.800% Senior Notes due July 15, 2030. The Senior Notes were sold to a group of financial institutions as initial purchasers who subsequently resold the Senior Notes to non-U.S. persons pursuant to Regulation S under the Securities Act, and to persons reasonably believed to be qualified institutional buyers pursuant to Rule 144A under the Securities Act at a purchase price equal to 99.921% of their principal amount. Interest on the Senior Notes is payable semi-annually in arrears on January 15 and July 15. The Senior Notes may be redeemed in whole or in part by the Company (a) at any time prior to April 15, 2030 at a redemption price equal to 100% of the principal amount of the Senior Notes, plus the Applicable Premium (as calculated in accordance with the indenture governing

the Senior Notes), and any accrued and unpaid interest, if any, on the principal amount of Senior Notes being redeemed to, but excluding, the redemption date, and (b) on or after April 15, 2030 at a redemption price equal to 100% of the principal amount of the Senior Notes, plus any accrued and unpaid interest, if any, on the principal amount of Senior Notes being redeemed to, but excluding, the redemption date. The Company’s obligations under the Senior Notes are guaranteed on a senior, unsecured basis by the Company’s domestic wholly owned subsidiaries and the indenture governing the Senior Notes contains covenants, events of default and other customary provisions with which the Company was in compliance as of December 31, 2023.

Revolving Credit Facility

On July 1, 2020, the Company entered into the 2020 Credit Agreement, which provides for a $750 million revolving credit facility with a term of five years (maturing July 1, 2025) and a letter of credit sublimit of $20 million from a syndicate of financial institutions as lenders and issuing banks. A commitment fee of 0.25% to 0.30% per annum, depending on the Total Leverage Ratio (defined in 2020 Credit Agreement), is payable quarterly in arrears based on the unused revolving commitment. The Company and the syndicate of lenders and issuing banks entered into the First Amendment of the 2020 Credit Agreement in May 2023, which replaced LIBOR as the reference rate with Term SOFR for U.S. dollar denominated borrowings, SONIA rates for Sterling denominated borrowings and EURIBOR for Euro denominated borrowings.

Borrowings under the 2020 Credit Agreement can be on a revolving basis or term basis, not to exceed the remaining term of the facility, and denominated in U.S. dollars, sterling, euros or other allowed currency at the Company's option, subject to a limit of $250 million U.S. dollar equivalent for non-U.S. dollar denominated borrowings. Borrowings bear interest at a floating rate which can be, at the Company’s option, either (a) an alternate base rate plus an applicable rate ranging from 0.50% to 1.25% or (b) a Term SOFR, SONIA rate or EURIBOR (with a floor of 0.0%) for the specified interest period plus an applicable rate ranging from 1.50% to 2.25%, in each case depending on the Company's Total Leverage Ratio (as defined in the 2020 Credit Agreement). Any borrowing with a Term SOFR reference rate includes an additional 0.10% credit spread adjustment.

Funds drawn down on the revolving credit facility pursuant to the 2020 Credit Agreement may be used for working capital and other general corporate purposes of the Company and its restricted subsidiaries. The obligations under the 2020 Credit Agreement are guaranteed by each of the Company’s current and future direct or indirect wholly owned restricted domestic subsidiaries, other than certain excluded subsidiaries, in each case subject to certain exceptions, pursuant to guarantee agreements.

The 2020 Credit Agreement includes covenants, including ones that, subject to certain exceptions, restrict the ability of the Company and its subsidiaries to (i) incur additional indebtedness, (ii) incur liens, (iii) pay dividends or make certain other restricted payments, investments or acquisitions, (iv) merge or consolidate with another person, and (v) sell, assign, lease or otherwise dispose of all or substantially all of our assets. In May 2023, the Company amended the 2020 Credit Agreement to replace LIBOR as the reference rate with Term SOFR for U.S. dollar-denominated borrowings, SONIA rates for Sterling-denominated borrowings and EURIBOR for Euro-denominated borrowings.

As of December 31, 2023, the Company is in a Covenant Suspension Period. During any Covenant Suspension Period, the Company will not be subject to certain of these covenants such as restrictions on the ability to incur indebtedness. The 2020 Credit Agreement also requires the Company to maintain a Total Leverage Ratio (as defined in the 2020 Credit Agreement) not exceeding 4.50 to 1.00. The Company was in compliance with the covenants in the 2020 Credit Agreement as of December 31, 2023.

As of December 31, 2023, the Company had no amounts drawn under this facility.

The Company had $1.6 million and $2.7 million of deferred debt issuance costs as of December 31, 2023 and 2022, respectively, in connection with the 2020 Credit Agreement. These amounts are included in deposits and other assets on the Company's consolidated balance sheets.

For the years ended December 31, 2023, 2022 and 2021, the Company recognized interest expense as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Interest on outstanding borrowings	$	28.0	$	28.0	$	28.0
Amortization of Senior Notes discount and issuance costs	2.4		2.3		2.3
Interest capitalized for construction in process	(1.6)		—		—
Commitment fees and other	2.6		2.0		2.0
Total interest expense	$	31.4	$	32.3	$	32.3

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INCOME TAXES

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

INCOME TAXES

INCOME TAXES

The components of the provision for income taxes attributable to operations consist of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
Current:
Federal	$	126.3	$	116.3	$	61.3
State	36.6		31.2		24.6
Foreign	0.9		0.7		1.3
Total current	163.8		148.2		87.2
Deferred:
Federal	(31.7)		(20.4)		22.9
State	(2.9)		(9.6)		8.5
Foreign	(2.6)		(1.2)		(7.2)
Total deferred	(37.2)		(31.2)		24.2
Total provision for income taxes	$	126.6	$	117.0	$	111.4

The components of deferred tax assets and liabilities consist of the following (in millions):

	December 31,
	2023		2022
Deferred tax assets:
Allowance for credit losses	$	5.8	$	3.4
Accrued compensation	11.9		4.6
Stock compensation	15.3		20.4
Net operating losses	34.7		26.8
Accrued reserve and other	5.8		6.7
Lease liabilities	21.8		26.4
Capitalized research and development costs	92.4		45.4
Research and development credits	4.5		6.1
Total deferred tax assets, prior to valuation allowance	192.2		139.8
Valuation allowance	(9.0)		(5.2)
Total deferred tax assets, net of valuation allowance	183.2		134.6
Deferred tax liabilities:
Deferred commission costs, net	(42.3)		(36.1)
Lease right-of-use assets	(16.0)		(18.2)
Prepaid expenses	(4.1)		(3.2)
Property and equipment, net	(25.1)		(25.8)
Intangible assets, net	(128.1)		(117.8)
Total deferred tax liabilities	(215.6)		(201.1)
Net deferred tax liabilities	$	(32.4)	$	(66.5)

For both the years ended December 31, 2023 and 2022, the Company has not recognized deferred tax liabilities for temporary differences related to investments in foreign subsidiaries that were deemed permanently reinvested. Determination of the amount of unrecognized deferred income tax liabilities on these earnings is not practicable because such liability, if any, depends on certain circumstances existing if and when remittance occurs. A deferred tax liability will be recognized if and when the Company no longer plans to permanently reinvest these undistributed earnings.

As of both December 31, 2023 and 2022, a valuation allowance has been established for certain deferred tax assets due to the uncertainty of realization. The valuation allowance as of both December 31, 2023 and 2022 includes an allowance for acquired net operating losses and foreign deferred tax assets.

The Company established the valuation allowance because it is more likely than not that a portion of the deferred tax asset for certain items will not be realized based on the weight of available evidence. A valuation allowance was established for the foreign deferred tax assets due to the cumulative loss in recent years in those jurisdictions. The Company has not had sufficient taxable income historically to utilize the foreign deferred tax assets, and it is uncertain whether the Company will generate sufficient taxable income in the future to utilize the deferred tax assets. The Company has established a valuation allowance for certain acquired net operating losses where Section 382 limitations will impact the ability of the Company to utilize the net operating losses before they expire.

The Company’s change in valuation allowance was an increase of approximately $3.8 million for the year ended December 31, 2023 and a decrease of approximately $0.5 million for the year ended December 31, 2022. The increase for the year ended December 31, 2023 was primarily due to an increase in foreign net operating loss deferred tax assets for which a full valuation allowance has been established. The decrease for the year ended December 31, 2022 was primarily due to an international restructuring.

The Company had U.S. income before income taxes of approximately $526.7 million, $493.2 million and $408.8 million for the years ended December 31, 2023, 2022 and 2021, respectively. The Company had foreign losses before income taxes of approximately $25.4 million, $6.7 million and $4.8 million for the years ended December 31, 2023, 2022 and 2021, respectively.

The Company’s provision for income taxes resulted in effective tax rates that varied from the statutory federal income tax rate as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Expected federal income tax provision at statutory rate	$	105.3	$	102.1	$	84.8
State income taxes, net of federal benefit	27.4		21.5		21.0
Increase (decrease) in valuation allowance	1.9		(0.5)		(5.0)
Research credits	(20.2)		(17.5)		(13.1)
Excess tax benefit	(5.9)		(1.8)		(10.9)
Tax reserves	4.2		1.5		(12.8)
Nondeductible compensation	8.8		11.4		10.4
International restructuring	0.1		(3.9)		34.9
Other adjustments	5.0		4.2		2.1
Income tax expense	$	126.6	$	117.0	$	111.4

The Company has net operating loss carryforwards for international income tax purposes of approximately $77.3 million that do not expire. The Company has federal net operating loss carryforwards of approximately $71.3 million that begin to expire in 2033, state net operating loss carryforwards with a tax value of approximately $0.4 million that begin to expire in 2033 and state income tax credit carryforwards with a tax value of approximately $8.0 million primarily relating to state research and development credits and the D.C. qualified high technology company tax credit that begin to expire in 2024. The Company realized a cash benefit relating to the use of its tax loss carryforwards of approximately $5.9 million, $12.6 million and $14.1 million in December 31, 2023, 2022 and 2021, respectively.

The following table summarizes the activity related to the Company’s unrecognized tax benefits (in millions):

Unrecognized tax benefit as of December 31, 2020	$	28.9
Increase for current year tax positions	3.1
Decrease for prior year tax positions	(5.4)
Decrease for settlements with taxing authorities	(9.9)
Expiration of the statute of limitation for assessment of taxes	(1.9)
Unrecognized tax benefit as of December 31, 2021	14.8
Increase for current year tax positions	3.4
Increase for prior year tax positions	0.3
Expiration of the statute of limitation for assessment of taxes	(2.3)
Unrecognized tax benefit as of December 31, 2022	16.2
Increase for current year tax positions	4.4
Increase for prior year tax positions	1.7
Expiration of the statute of limitation for assessment of taxes	(2.4)
Unrecognized tax benefit as of December 31, 2023	$	19.9

Approximately $19.9 million and $16.2 million of the unrecognized tax benefits as of December 31, 2023 and 2022, respectively, would favorably affect the annual effective tax rate if recognized in future periods. The increase for current year tax positions of $4.4 million and increase for prior year tax positions of $1.7 million for the year ended December 31, 2023 were primarily attributable to research credits and state apportionment reserves. The decrease for expiration of the statute of limitation of $2.4 million for the year ended December 31, 2023 was attributable to research credits. The Company recognized $0.7 million, recognized $0.1 million and reversed $0.4 million for interest and penalties in its consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021, respectively. The Company had liabilities of $1.4 million, $0.7 million, and $0.6 million for interest and penalties in its consolidated balance sheets as of December 31, 2023, 2022 and 2021, respectively. The Company does not anticipate the amount of the unrecognized tax benefits will change significantly over the next 12 months.

The Company is subject to taxation in the U.S. federal jurisdiction and various states and foreign jurisdictions. The Company’s federal income tax returns for tax years 2015 and 2020 through 2022 remain open to examination. Most of the Company’s state income tax returns for tax years 2020 through 2022 remain open to examination. For states that have a four-year statute of limitations, the state income tax returns for tax years 2019 through 2022 remain open to examination. The Company’s U.K. income tax return for tax year 2022 remains open to examination. The Company believes that an adequate provision has been made for any adjustments that may result from tax examinations.

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COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES

The following summarizes the Company's significant contractual obligations, including related payments due by period, as of December 31, 2023 (in millions):

Year Ending December 31,	Operating lease obligations		Finance lease obligations		Long-term debt principal payments		Long-term debt principal interest payments
2024	$	39.0	$	3.9	$	—	$	28.0
2025	25.4		3.9		—		28.0
2026	15.1		3.9		—		28.0
2027	13.1		2.9		—		28.0
2028	10.7		—		—		28.0
Thereafter	6.6		—		1,000.0		56.0
Total	$	109.9	$	14.6	$	1,000.0	$	196.0

The Company leases office facilities under various non-cancelable operating leases, as well as, data centers, and vehicles under finance lease arrangements. The leases contain various renewal options.

See Note 7 for further discussion of the Company's lease commitments.

Currently, and from time to time, the Company is involved in litigation incidental to the conduct of its business. The Company records a provision for a liability when it is both probable that a liability has been incurred and the amount can be reasonably estimated. While it is reasonably possible that an unfavorable outcome may occur as a result of one or more of the Company’s current litigation matters, at this time management has concluded that the resolutions of these matters are not expected to have a material effect on the Company's consolidated financial position, future results of operations or liquidity. Legal defense costs are expensed as incurred.

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SEGMENT REPORTING

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

SEGMENT REPORTING

SEGMENT REPORTING

Segment Information

The Company manages its business geographically in two operating segments, with the primary areas of measurement and decision-making being North America, which includes the U.S. and Canada, and International, which primarily includes Europe, Asia-Pacific and Latin America. Management relies on an internal management reporting process that provides revenue and operating segment EBITDA. Management believes that operating segment EBITDA is an appropriate measure for evaluating the operational performance of the Company’s operating segments. EBITDA is used by management to internally measure operating and management performance and to evaluate the performance of the business. However, this measure should be considered in addition to, not as a substitute for or superior to, income from operations or other measures of financial performance prepared in accordance with GAAP.

Summarized EBITDA information by operating segment consists of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
North America	$	403.0	$	577.3	$	557.1
International	(13.2)		5.4		7.9
Total EBITDA	$	389.8	$	582.7	$	565.0

The reconciliation of net income to EBITDA consists of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
Net income	$	374.7	$	369.5	$	292.6
Amortization of acquired intangible assets in cost of revenues	31.5		29.0		28.8
Amortization of acquired intangible assets in operating expenses	42.2		73.6		74.8
Depreciation and other amortization	33.8		29.1		29.1
Interest (income) expense, net	(213.6)		(32.1)		31.6
Other (income), net	(5.4)		(3.4)		(3.3)
Income tax expense	126.6		117.0		111.4
EBITDA	$	389.8	$	582.7	$	565.0

Summarized information by operating segment consists of the following (in millions):

	December 31,
	2023		2022
Property and equipment, net
North America	$	465.7	$	320.3
International	6.5		1.0
Total property and equipment, net	$	472.2	$	321.3
Goodwill
North America	$	2,149.2	$	2,149.2
International	237.0		165.6
Total goodwill	$	2,386.2	$	2,314.8
Assets
North America	$	8,505.5	$	8,146.3
International	414.2		256.2
Total assets	$	8,919.7	$	8,402.5
Liabilities
North America	$	1,499.7	$	1,486.3
International	81.4		46.2
Total liabilities	$	1,581.1	$	1,532.5

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STOCKHOLDERS' EQUITY

12 Months Ended

Dec. 31, 2023

Stockholders' Equity Note [Abstract]

STOCKHOLDERS' EQUITY

STOCKHOLDER'S EQUITY

Preferred Stock

The Company has 2 million shares of preferred stock, $0.01 par value, authorized for issuance. The Board of Directors may issue the preferred stock from time to time as shares of one or more classes or series.

Common Stock

The Company has 1.2 billion shares of common stock, $0.01 par value, authorized for issuance. Dividends may be declared and paid on the common stock, subject in all cases to the rights and preferences of the holders of preferred stock and authorization by the Board of Directors. In the event of liquidation or winding up of the Company and after the payment of all preferential amounts required to be paid to the holders of any series of preferred stock, any remaining funds shall be distributed among the holders of the issued and outstanding common stock.

Common Stock Split

At the Company's 2021 Annual Meeting of Stockholders in June 2021, upon the recommendation of the Company's Board of Directors, the Company's stockholders approved the adoption of the Company's Fourth Amended and Restated Certificate of Incorporation, which increased the total number of shares of common stock that the Company is authorized to issue from 60 million to 1.2 billion. The Fourth Amended and Restated Certificate of Incorporation became effective on June 7, 2021. On June 7, 2021, the Board of Directors approved a ten-for-one stock split of the Company's outstanding shares of common stock to be effected in the form of a stock dividend. Each stockholder of record on June 17, 2021 received a dividend of nine additional shares of common stock for each then-held share, distributed after close of trading on June 25, 2021. The par value of the Company's common stock remained $0.01 per share. All applicable share and per-share amounts in the consolidated financial statements and the accompanying notes have been retroactively adjusted to reflect the impact of the stock split.

Equity Offerings

On September 20, 2022, the Company completed a public equity offering of 10.7 million shares of common stock at an offering price of $70.38 per share. Net proceeds from the public equity offering were approximately $745.7 million, after deducting approximately $4.3 million of underwriting fees, commissions and other stock issuance costs. On May 28, 2020, the Company completed a public equity offering of 26.3 million shares of common stock for $65.50 per share. Net proceeds from the public equity offering were approximately $1.7 billion, after deducting approximately $35 million of underwriting fees, commissions and other stock issuance costs. The Company intends to use the net proceeds from the sale of the securities to fund all or a portion of the costs of any strategic acquisitions it pursues in the future, to finance the growth of its business and for working capital and other general corporate purposes. General corporate purposes may include additions to working capital, capital expenditures, repayment of debt, investments in the Company’s subsidiaries and the repurchase, redemption or retirement of securities, including the Company’s common stock.

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NET INCOME PER SHARE

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

NET INCOME PER SHARE

NET INCOME PER SHARE

The following table sets forth the calculation of basic and diluted net income per share (in millions, except per share data):

	Year Ended December 31,
	2023		2022		2021
Numerator:
Net income	$	374.7	$	369.5	$	292.6
Denominator:
Denominator for basic net income per share — weighted-average outstanding shares	405.3		396.3		392.2
Effect of dilutive securities:
Stock options, restricted stock awards and restricted stock units	1.6		1.5		2.0
Denominator for diluted net income per share — weighted-average outstanding shares	406.9		397.8		394.2
Net income per share — basic	$	0.92	$	0.93	$	0.75
Net income per share — diluted	$	0.92	$	0.93	$	0.74

The following table summarizes the shares underlying the unvested performance-based restricted stock and anti-dilutive securities excluded from the basic and diluted earnings per share calculations (in millions):

	Year Ended December 31,
	2023	2022	2021
Performance-based restricted stock awards	0.2	0.4	0.4
Anti-dilutive securities	0.7	1.0	0.4

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EMPLOYEE BENEFIT PLANS

12 Months Ended

Dec. 31, 2023

Compensation Related Costs [Abstract]

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS Stock Incentive Plans

In April 2007, the Company’s Board of Directors adopted the CoStar Group 2007 Stock Incentive Plan (as amended, the “2007 Plan”), subject to stockholder approval, which was obtained on June 7, 2007. In April 2016, the Company’s Board of Directors adopted the CoStar Group 2016 Stock Incentive Plan (as amended, the “2016 Plan”), subject to stockholder approval, which was obtained on June 9, 2016. All shares of common stock that were authorized for issuance under the 2007 Plan that, as of June 9, 2016, remained available for issuance under the 2007 Plan (excluding shares subject to outstanding awards) were rolled into the 2016 Plan and, as of that date, no shares of common stock were available for new awards under the 2007 Plan. The 2007 Plan continues to govern vested unexercised stock options issued prior to June 9, 2016. Upon the occurrence of a Change of Control, as defined in the 2007 Plan, all outstanding unexercisable options under the 2007 Plan immediately become exercisable.

The 2016 Plan provides for the grant of stock options, restricted stock, restricted stock units and stock appreciation rights to officers, employees and directors of the Company and its subsidiaries. Stock options granted under the 2016 Plan may be non-qualified or may qualify as incentive stock options. Except in limited circumstances related to a merger or other acquisition, the exercise price for an option may not be less than the fair market value of the Company’s common stock on the date of grant. The vesting period for each grant of options, restricted stock, restricted stock units and stock appreciation rights under the 2016 Plan is determined by the Board of Directors or a committee thereof and is generally three to four years, subject to minimum vesting periods for restricted stock and restricted stock units of at least one year. In some cases, vesting of awards under the 2016 Plan may be based on performance conditions. The Company initially reserved approximately 22.7 million shares of common stock for issuance under the 2016 Plan, which included shares of common stock that were authorized and remained available for issuance under the 2007 Plan as of June 9, 2016. Any shares of common stock subject to (a) outstanding awards under the 2007 Plan as of June 9, 2016 or (b) outstanding awards under the 2016 Plan after June 9, 2016, that cease for any reason to be subject to such awards (other than by reason of exercise or settlement of the awards to the extent they are exercised or settled in vested and nonforfeitable shares) will become authorized and unissued under the 2016 Plan. Pursuant to the terms of the 2016 Plan, all amounts reserved or issued under the plan were adjusted to reflect the Company’s ten-for-one common stock split. Unless terminated sooner, the 2016 Plan will terminate in June 2026, but will continue to govern

unexercised and unexpired awards issued under the 2016 Plan prior to that date. Approximately 13.4 million shares were available for future grant under the 2016 Plan as of December 31, 2023.

At December 31, 2023, there was approximately $115.3 million of unrecognized compensation cost related to stock incentive plans, net of estimated forfeitures, which the Company expects to recognize over a weighted-average-period of 2.4 years. The income tax benefit realized from stock-based compensation was $6.8 million, immaterial  and $2.4 million for the years ended December 31, 2023, 2022 and 2021, respectively.

See Notes 2 and 12 for further discussion of stock-based compensation expense and income taxes, respectively.

Stock Options

Option activity was as follows:

	Number of Shares	Range of Exercise Price	Weighted- Average Exercise Price		Weighted- Average Remaining Contract Life (in years)	Aggregate Intrinsic Value (in millions)
Outstanding at December 31, 2020	2,023,100	$10.22 - $66.65	$	34.18	6.99	$	117.8
Granted	159,000	$91.98	$	91.98
Exercised	(206,000)	$20.49 - $39.82	$	30.78
Outstanding at December 31, 2021	1,976,100	$10.22 - $91.98	$	39.18	6.24	$	80.8
Granted	202,100	$67.29	$	67.29
Exercised	—
Canceled or expired	—
Outstanding at December 31, 2022	2,178,200	$10.22 - $91.98	$	41.79	5.60	$	79.6
Granted	140,800	$76.78	$	76.78
Exercised	(419,340)	$10.22 - $34.21	$	17.77
Canceled or expired	—
Outstanding at December 31, 2023	1,899,660	$20.49 - $91.98	$	49.69	5.53	$	72.4
Exercisable at December 31, 2021	1,473,420	$10.22 - $66.65	$	29.55	5.59	$	72.9
Exercisable at December 31, 2022	1,766,070	$10.22 - $91.98	$	34.40	4.96	$	76.5
Exercisable at December 31, 2023	1,571,105	$20.49 - $91.98	$	44.32	4.93	$	68.1

The aggregate intrinsic value of outstanding options is calculated as the difference between (i) the closing price of the common stock at the end of the period and (ii) the exercise price of the underlying awards, multiplied by the number of outstanding options as of the end of the period that had an exercise price less than the closing price on that date. The aggregate intrinsic value of options exercised, determined as of the exercise date, was approximately $24.3 million and $11.0 million for the years ended December 31, 2023 and 2021, respectively. No options were exercised in the year ended December 31, 2022.

The Company estimated the fair value of each option granted on the date of grant using the Black-Scholes option-pricing model, using the assumptions in the following table:

	Year Ended December 31,
	2023			2022			2021
Dividend yield	0		%	0		%	0		%
Expected volatility	35		%	31		%	30		%
Risk-free interest rate	3.96		%	1.89		%	0.56		%
Expected life (in years)	5			5			5
Weighted-average grant date fair value	$	28.87		$	20.43		$	25.09

The expected dividend yield is determined based on the Company's past cash dividend history and anticipated future cash dividend payments. The Company has never declared nor paid any dividends on its common stock and does not anticipate paying any dividends on its common stock during the foreseeable future, but intends to retain any earnings for future growth of its business. Expected volatility is calculated based on historical volatility of the daily closing price of the Company's common stock over a period consistent with the expected life of the options granted. The risk-free interest rate is based on the U.S. Treasury rate with terms similar to the expected life of the options granted. The expected life for the options is determined based on multiple factors, including historical employee behavior patterns of exercising options and post-employment termination behavior as well as expected future employee option exercise patterns.

The following table summarizes information regarding options outstanding at December 31, 2023:

	Options Outstanding				Options Exercisable
Range of Exercise Price	Number of Shares	Weighted-Average Remaining Contractual Life (in years)	Weighted- Average Exercise Price		Number of Shares	Weighted- Average  Exercise Price
$20.49 - $27.35	346,000	3.16	$	20.49	346,000	$	20.49
$27.36 - $37.02	354,090	4.16	$	34.21	354,090	$	34.21
$37.03 - $53.24	385,670	5.10	$	39.82	385,670	$	39.82
$53.25 - $66.97	312,000	6.10	$	66.65	312,000	$	66.65
$66.98 - $91.98	501,900	8.09	$	77.77	173,345	$	82.39
	1,899,660	5.53	$	49.69	1,571,105	$	44.32

Restricted Stock Awards

The Compensation Committee of the Board of Directors of the Company historically approved grants of restricted common stock to employees and directors of the Company that vest over a specific service period and to executive officers that vest based on the achievement of certain performance conditions, primarily, the achievement of a three-year cumulative revenue goal established at the grant date. The grant of awards with performance conditions supports the Company’s goal of aligning executive incentives with long-term stockholder value and ensuring that executive officers have a continuing stake in the long-term success of the Company.

The vesting of restricted common stock is subject to continuing employment requirements. Certain performance-based restricted common stock awards are also subject to a market condition such that the actual number of shares that vest at the end of the respective three-year period is determined based on the Company’s achievement of performance goals and an established Company specific TSR factor relative to the S&P 500 Index over the same three-year performance period. At the end of the three-year performance period, if the performance condition is achieved at or above the pre-established threshold, the number of shares earned is further adjusted by a TSR payout percentage, which ranges between 80% and 120%, based on the Company’s TSR performance relative to that of S&P 500 Index over the respective three-year period.

The Company estimates the fair value of its equity awards with both a performance and market condition on the date of grant using a Monte-Carlo simulation valuation model. This pricing model uses multiple simulations to evaluate the probability of achieving the market condition to calculate the fair value of the awards. Expense is only recorded for awards that are expected to vest, net of estimated forfeitures. The assumptions used to estimate the fair value of awards with both a performance and a market condition were as follows:

	Year Ended December 31,
	2023			2022			2021
Dividend yield	0		%	0		%	0		%
Expected volatility	37		%	34		%	42		%
Risk-free interest rate	4.31		%	1.71		%	0.20		%
Expected life (in years)	3			3			3
Weighted-average grant date fair value	$	81.58		$	71.19		$	99.73

The expected dividend yield is determined based on the Company's past cash dividend history and anticipated future cash dividend payments. The Company has never declared nor paid any dividends on its common stock and does not anticipate paying any dividends on its common stock during the foreseeable future, but intends to retain any earnings for future growth of its business. Expected volatility is calculated based on historical volatility of the daily closing price of the common stock of the companies within the S&P 500 Index over a period consistent with the expected life of the awards. The risk-free interest rate is based on the U.S. Treasury rate with terms similar to the expected life of the awards. The expected life is consistent with the performance measurement period of the awards.

As of December 31, 2023, the Company determined that it was probable that at least the minimum performance goals associated with restricted stock awards with performance and market conditions granted during 2023, 2022 and 2021 would be met by their forfeiture dates. The Company recorded a total of approximately $13.6 million, $11.9 million and $8.0 million of stock-based compensation expense related to restricted stock awards with performance and market conditions for the years ended December 31, 2023, 2022 and 2021, respectively. As of December 31, 2023, the Company expects to record an aggregate stock-based compensation expense of approximately $14.0 million for restricted stock awards with performance and market conditions over the periods 2024, 2025 and 2026.

The following table presents unvested restricted stock awards activity for the year ended December 31, 2023:

	Restricted Stock Awards — without Market Condition			Restricted Stock Awards — with Market Condition
	Number of Shares	Weighted-Average Grant Date Fair Value per Share		Number of Shares	Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock awards at December 31, 2022	2,061,894	$	67.15	620,880	$	80.55
Granted	1,096,446	$	73.27	283,440	$	81.58
Vested	(787,883)	$	66.51	(90,408)	$	72.69
Canceled	(230,546)	$	68.58	(132,792)	$	72.69
Unvested restricted stock awards at December 31, 2023	2,139,911	$	70.38	681,120	$	83.56

Restricted Stock Units

The following table presents unvested restricted stock units activity for the year ended December 31, 2023:

	Number of Units	Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock units at December 31, 2022	21,560	$	65.24
Granted	10,465	$	70.74
Vested	(8,129)	$	65.77
Canceled	(977)	$	68.34
Unvested restricted stock units at December 31, 2023	22,919	$	67.43

Management Stock Purchase Plan

The Board of Directors adopted the Company’s Management Stock Purchase Plan in December 2017 with the intent of providing selected key employees of the Company and its subsidiaries, including the Company's executive officers, the opportunity to defer a portion of their cash incentive compensation and to align management and stockholder interests through awards of DSUs under the MSPP and awards of Matching RSUs issued under the 2016 Plan. Under this plan participants are permitted to elect to defer up to 100% of their annual incentive bonus or commissions earned during the year by submitting an irrevocable election in accordance with Section 409A of the Internal Revenue Code, as amended. On the date the incentive bonus or commission would otherwise be paid in cash (typically during the following calendar year), the Company awards the participant DSUs representing the number of shares of common stock with an aggregate fair market value on that date equal to the amount of compensation elected to be deferred under the MSPP. On the same date the DSUs are awarded, the participant

receives a grant of Matching RSUs covering the number of shares of common stock equal up to 100% of the DSUs granted. The expense related to the DSUs is recognized on a straight-line basis during the period that the related incentive bonus or commission is earned. The Company granted 82,374 and 75,479 DSUs during the years 2023 and 2022, respectively. The expense related to the Matching RSUs is recognized over the four-year vesting period following the grant date.

The following tables presents the Matching RSU activity for the year ended December 31, 2023:

	Number of Matching RSU Shares	Weighted-Average Grant Date Fair Value per Share
Unvested MSPP restricted stock units at December 31, 2022	180,431	$	60.52
Granted	82,374	$	67.36
Vested	(52,710)	$	46.91
Canceled	(13,128)	$	66.67
Unvested MSPP restricted stock units at December 31, 2023	196,967	$	66.61

Employee 401(k) Plan

The Company maintains a 401(k) Plan as a defined contribution retirement plan for all eligible employees. The 401(k) Plan provides for tax-deferred contributions of employees’ salaries, limited to a maximum annual amount as established by the IRS. In addition to the traditional 401(k), effective January 1, 2015, eligible employees have the option of making an after-tax contribution to a Roth 401(k) plan or a combination of both. In each of 2023, 2022 and 2021, the Company matched 100% of employee contributions up to a maximum of 4% of total compensation. Amounts contributed to the 401(k) Plan by the Company to match employee contributions for the years ended December 31, 2023, 2022 and 2021 were approximately $25.5 million, $21.5 million and $17.6 million, respectively. The Company had no administrative expenses in connection with the 401(k) Plan for each of the years ended December 31, 2023, 2022 and 2021.

Employee Pension Plan

The Company maintains a GPP Plan for all eligible employees in the Company’s U.K. offices. The GPP Plan is a defined contribution plan. Employees are eligible to contribute a portion of their salaries, subject to a maximum annual amount as established by Her Majesty's Revenue and Customs. In each of 2023, 2022 and 2021, the Company's matching contribution was based on the percentage contributed by the employee, up to a maximum of 6% of total compensation. Amounts contributed to the GPP Plan by the Company to match employee contributions for the years ended December 31, 2023, 2022 and 2021, were approximately $1.2 million, $1.0 million and $0.9 million, respectively.

Registered Retirement Savings Plan

As of January 1, 2015, the Company introduced a RRSP for all eligible employees in the Company’s Canadian offices. In each of the years ended December 31, 2023, 2022 and 2021, the Company matched 100% of employee contributions up to a maximum of 4% of total compensation. Amounts contributed to the RRSP by the Company to match employee contributions were approximately $0.2 million for the year ended December 31, 2023, and $0.1 million for both of the years ended December 31, 2022 and 2021.

Employee Stock Purchase Plan

As of August 1, 2006, the Company introduced an ESPP, pursuant to which eligible employees participating in the plan authorize the Company to withhold specified amounts from the employees’ compensation and use the withheld amounts to purchase shares of the Company's common stock at 90% of the market price. Participating employees are able to purchase common stock under this plan during each offering period. An offering period begins the second Saturday before each of the Company’s regular pay dates and ends on each of the Company’s regular pay dates. On June 2, 2021, the Company’s stockholders approved an amendment to the ESPP to increase the number of shares available for purchase under the ESPP by 1 million shares. The Company registered the issuance of these additional shares under the ESPP pursuant to the registration statement filed on July 28, 2021. There were 782,328 and 1,010,267 shares available for purchase under the ESPP as of December 31, 2023 and 2022, respectively, and approximately 227,939 and 223,596 shares of the Company’s common stock were purchased under the ESPP during 2023 and 2022, respectively.

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SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTSIn January 2024, the Company entered into a conditional purchase and sale agreement for an office building in Arlington, Virginia. The Company closed on the transaction in February 2024 along with an agreement to purchase the land underlying the building. These transactions totaled $340.0 million, inclusive of property taxes, titling insurance and other transaction costs and were paid with cash on hand.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation

The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Accounting policies are consistent for each operating segment.

Use of Estimates

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company evaluates its estimates and assumptions, including those related to revenue recognition, allowance for credit losses, the useful lives and recoverability of long-lived and intangible assets, goodwill, income taxes, accounting for business combinations, stock-based compensation, estimating the Company's incremental borrowing rate for its leases, and contingencies, among others. The Company bases these estimates on historical and anticipated results, trends and various other assumptions that it believes are reasonable, including assumptions as to future events. These estimates form the basis for making judgments about the carrying values of assets and liabilities and recorded revenues and expenses. Actual results could differ from these estimates.

Revenue Recognition

Revenue Recognition

The Company derives revenues primarily by (i) providing access to its proprietary database of commercial real estate information and (ii) providing online marketplaces for professional property management companies, property owners, real estate agents and brokers and landlords, in each case, typically through a fixed monthly fee for its subscription-based services. Other subscription-based services include (i) real estate and lease management solutions to commercial customers, real estate investors and lenders, (ii) access to applications to manage workflow and advertising and marketing services for residential real estate agents through its Homes.com Network and the acquisition of OnTheMarket, (iii) benchmarking and analytics for the hospitality industry and (iv) market research, portfolio and debt analysis, management and reporting capabilities.

Subscription contract rates are generally based on the number of sites, number of users, organization size, the client’s business focus, geography, the number of properties reported on or analyzed, the number and types of services to which a client subscribes, the number of properties a client advertises and the prominence and placement of a client's advertised properties in the search results. The Company’s subscription-based license agreements typically renew automatically, and a majority have a term of at least one year. Revenue from our subscription-based contracts was approximately 95%, 93% and 93% of total revenue for the years ended December 31, 2023, 2022 and 2021, respectively.

The Company also derives revenues from transaction-based services including: (i) an online auction platform for commercial real estate through Ten-X, (ii) providing online tenant applications, including background and credit checks, and rental payment processing and (iii) ancillary products and services that are sold on an ad hoc basis.

The Company analyzes contracts to determine the appropriate revenue recognition using the following steps: (i) identification of contracts with customers, (ii) identification of distinct performance obligations in the contract, (iii)

determination of contract transaction price, (iv) allocation of contract transaction price to the performance obligations and (v) determination of revenue recognition based on timing of satisfaction of the performance obligations.

The Company recognizes revenues upon the satisfaction of its performance obligation(s) (upon transfer of control of promised services to its customers) in an amount that reflects the consideration to which it expects to be entitled to in exchange for those services. Revenues from subscription-based services are recognized on a straight-line basis over the term of the agreement. Revenues from transaction-based services are recognized when the promised product or services are delivered, which, in the case of Ten-X auctions, is at the time of a successful closing for the sale of the property.

In limited circumstances, the Company's contracts with customers include promises to transfer multiple services, such as contracts for its subscription-based services and professional services. For these contracts, the Company accounts for individual performance obligations separately if they are distinct, which involves the determination of the standalone selling price for each distinct performance obligation.

Deferred revenue results from amounts billed in advance to customers or cash received from customers in advance of the Company's fulfillment of its performance obligation(s) and is recognized as those obligations are satisfied.

Contract assets represent a conditional right to consideration for satisfied performance obligations that become a receivable when the conditions are satisfied. Contract assets are generated when contractual billing schedules differ from revenue recognition timing.

Certain sales commissions are considered incremental and recoverable costs of obtaining a contract with a customer. Sales commissions incurred for obtaining new contracts are deferred and then amortized as selling and marketing expenses on a straight-line basis over a period of benefit that the Company has determined to be three years. The three-year amortization period was determined based on several factors, including the nature of the technology and proprietary data underlying the services being purchased, customer contract renewal rates and industry competition. Sales commissions that do not represent incremental costs of obtaining a contract, or that would otherwise be amortized over a period of one year or less, are not subject to capitalization.

See Note 3 for further discussion of the Company's revenue recognition.

Cost of Revenues

Cost of Revenues

Cost of revenues principally consists of salaries, benefits, bonuses, stock-based compensation expenses and other indirect costs for the Company's researchers who collect and analyze the real estate data that is the basis for the Company's information, analytics and online marketplaces and for employees that support these products. Additionally, cost of revenues includes the cost of data from third-party data sources, product hosting costs, and costs related to advertising purchased on behalf of customers, credit card and other transaction fees relating to processing customer transactions, which are expensed as incurred, and the amortization of acquired trade names, technology and certain other intangible assets.

Foreign Currency Translation

Foreign Currency Translation

The Company’s reporting currency is the U.S. dollar. The functional currency for the majority of its operations is the local currency, with the exception of certain international locations for which the functional currency is the British Pound. Assets and liabilities denominated in a foreign currency are translated into U.S. dollars using the exchange rates in effect as of the balance sheet date. Gains and losses resulting from translation are included in accumulated other comprehensive loss. Currency gains and losses on the translation of intercompany loans made to foreign subsidiaries that are of a long-term investment nature are also included in accumulated other comprehensive loss. Gains and losses resulting from transactions denominated in a currency other than the functional currency of the entity are included in other income, net in the consolidated statements of operations using the average exchange rates in effect during the period.

Advertising Costs

Advertising Costs

The Company expenses advertising costs as incurred. Advertising costs include digital marketing, television, radio, print and other media advertising

Income Taxes

Income Taxes

Deferred income taxes result from temporary differences between the tax basis of assets and liabilities and the basis reported in the Company’s consolidated financial statements. Deferred tax liabilities and assets are determined based on the difference between the financial statement and the tax basis of assets and liabilities using enacted rates in effect during the year in which the Company expects differences to reverse. Valuation allowances are provided against assets, including net operating losses, if the Company determines it is more likely than not that some portion or all of an asset may not be realized. Interest and penalties related to income tax matters are recognized in income tax expense.

The Company has elected to record the GILTI under the current-period cost method.

See Note 12 for further discussion of income taxes.

Net Income Per Share

Net Income Per Share

Net income per share is computed by dividing net income by the weighted-average number of common shares outstanding during the period on a basic and diluted basis. The Company's potentially dilutive securities include outstanding stock options, unvested stock-based awards, which include restricted stock awards that vest over a specific service period, restricted stock awards with a performance and market condition, restricted stock units and Matching RSUs awarded under the MSPP. Shares underlying unvested restricted stock awards that vest based on a performance and market condition that have not been achieved as of the end of the period are not included in the computation of basic or diluted earnings per share. Diluted net income per share considers the impact of potentially dilutive securities except when the inclusion of the potentially dilutive securities would have an anti-dilutive effect.

See Note 16 for further discussion of the Company's calculation of net income per share.

Stock-Based Compensation

Stock-Based Compensation

Equity instruments issued in exchange for services performed by officers, employees and directors of the Company are accounted for using a fair-value based method and the fair value of such equity instruments is recognized as expense in the consolidated statements of operations.

For stock-based awards that vest over a specific service period, compensation expense is measured based on the fair value of the awards at the grant date and is recognized on a straight-line basis over the service period of the awards, net of an estimated forfeiture rate. For equity instruments that vest based on achievement of both a performance and market condition, stock-based compensation expense is recognized over the service period of the awards based on the expected achievement of the related performance conditions at the end of each reporting period. If the Company's initial estimates of the achievement of the performance conditions change, the related stock-based compensation expense may fluctuate from period to period based on those estimates. If the performance conditions are not met, no stock-based compensation expense will be recognized and any previously recognized stock-based compensation expense will be reversed. For awards with both a performance and a market condition, the Company estimates the fair value of each equity instrument granted on the date of grant using a Monte-Carlo simulation model. This pricing model uses multiple simulations to evaluate the probability of achieving the market condition to calculate the fair value of the awards which includes the recent market price and volatility of the Company's shares. When

determining the grant date fair value of all stock-based awards, the Company considers whether it is in possession of any material, non-public information that upon its release would have a material effect on its share price, and if so, whether the observable share price or expected volatility assumptions used in determining the fair value of the awards should be adjusted.

The Company estimates the fair value of its equity awards with both a performance and market condition on the date of grant using a Monte-Carlo simulation valuation model. This pricing model uses multiple simulations to evaluate the probability of achieving the market condition to calculate the fair value of the awards. Expense is only recorded for awards that are expected to vest, net of estimated forfeitures.

Cash and Cash Equivalents

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents.

Concentration of Credit Risk and Financial Instruments

Concentration of Credit Risk and Financial Instruments

The Company’s customer base creates a lack of dependence on any individual customer that mitigates the risk of nonpayment of the Company’s accounts receivable. No single customer accounted for more than 5% of the Company’s revenues for each of the years ended December 31, 2023, 2022 and 2021. The carrying amount of the accounts receivable approximates the net realizable value.

The Company holds cash at major financial institutions that often exceed Federal Deposit Insurance Corporation-insured limits. The Company manages its credit risk associated with cash concentrations by diversifying cash holdings across AAA rated Government and Treasury Money Market Funds and multiple high quality financial institutions, and by periodically evaluating the credit quality of the primary financial institutions holding such deposits. The carrying value of cash approximates fair value. Historically, the Company has not experienced any losses due to such cash concentrations.

Allowance for Credit Losses

Allowance for Credit Losses

The Company maintains an allowance for credit losses to cover its current expected credit losses on its trade receivables and contract assets arising from the failure of customers to make contractual payments. The Company estimates credit losses expected over the life of its trade receivables and contract assets based on historical information combined with current conditions that may affect a customer’s ability to pay and reasonable and supportable forecasts. While the Company uses various credit quality metrics, it primarily monitors collectability by reviewing the duration of collection pursuits on its delinquent trade receivables and historical write-off trends. Based on the Company’s experience, the customer's delinquency status, which is analyzed periodically, is the strongest indicator of the credit quality of the underlying trade receivables. The Company’s policy is to write-off trade receivables when they are deemed uncollectible. A majority of the Company's trade receivables are less than 365 days outstanding.

Under the CECL impairment model, the Company develops and documents its allowance for credit losses on its trade receivables based on five portfolio segments. The determination of portfolio segments is based primarily on the qualitative consideration of the nature of the Company’s business operations and the characteristics of the underlying trade receivables, as follows:

•CoStar Portfolio Segment - The CoStar portfolio segment consists of two classes of trade receivables based on geographical location: North America and International.

•Information Services Portfolio Segment - The Information Services portfolio segment consists of four classes of trade receivables: CoStar Real Estate Manager; Information Services, North America; STR, North America; and STR, International.

•Multifamily Portfolio Segment - The Multifamily portfolio segment consists of one class of trade receivables.

•LoopNet Portfolio Segment - The LoopNet portfolio segment consists of one class of trade receivables.

•Other Marketplaces Portfolio Segment - The Other Marketplaces portfolio segment consists of two classes of trade receivables: Ten-X and other marketplaces.

The majority of Residential revenue is e-commerce based and does not result in accounts receivable. Residential accounts receivable and the related allowance for credit losses are not material.

See Note 4 for further discussion of the Company’s accounting for allowance for credit losses.

Leases

Leases

The determination of whether an arrangement contains a lease and the classification of a lease, if applicable, is made at the commencement of the arrangement, at which time the Company also measures and recognizes an ROU asset, representing the Company’s right to use the underlying asset, and a lease liability, representing the Company’s obligation to make lease payments under the terms of the arrangement. For the purposes of recognizing ROU assets and lease liabilities associated with the Company’s leases, the Company has elected the practical expedient to not recognize a ROU asset or lease liability for short-term leases, which are leases with a term of 12 months or less. The lease term is defined as the noncancelable portion of the lease term, plus any periods covered by an option to extend the lease if it is reasonably certain that the option will be exercised.

In determining the amount of lease payments used in measuring ROU assets and lease liabilities, the Company has elected the practical expedient not to separate non-lease components from lease components for all classes of underlying assets. Consideration deemed part of the lease payments used to measure ROU assets and lease liabilities generally includes fixed payments and variable payments based on either an index or a rate, offset by lease incentives. Upon commencement, the initial ROU asset also includes any lease prepayments. ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. The rates implicit within the Company's leases are generally not determinable. Therefore, the Company's incremental borrowing rate is used to determine the present value of lease payments. The determination of the Company’s incremental borrowing rate requires judgment and is determined at lease commencement and is subsequently reassessed upon a modification to the lease arrangement.

Lease costs related to the Company's operating leases are generally recognized as a single ratable lease cost over the lease term. ROU assets resulting from finance leases are accounted for as property and equipment, net.

See Note 7 for further discussion of the Company’s accounting for leases.

Property and Equipment, Net

Property and Equipment, Net

Property and equipment are stated at cost, net of accumulated depreciation and amortization. All repairs and maintenance costs are expensed as incurred. Costs related to acquisition of additional aircraft components or the replacement of existing aircraft components are capitalized and depreciated over the estimated useful life of the aircraft or the added or replaced component, whichever is less. Depreciation and amortization are calculated on a straight-line basis over the following estimated useful lives of the assets:

Buildings	Twenty to thirty-nine years
Land	Indefinite
Aircrafts	Ten to twenty years
Furniture and office equipment	Five to ten years
Vehicles	Four to five years
Computer hardware and software	Three to five years
Leasehold improvements	Shorter of lease terms or useful life

Qualifying internal-use software costs incurred during the application development stage, which consist primarily of internal product development costs, are capitalized and amortized over the estimated useful life of the asset. All other costs are expensed as incurred. The Company removes fully depreciated property and equipment from the cost and accumulated depreciation amounts disclosed in the period they become fully depreciated.

In January 2021, the Company purchased an office building located in Richmond, Virginia, together with the land and assumed an existing lease for a purchase price of $131 million, inclusive of property taxes, title insurance and other transaction costs. The purchase of the Richmond building was accounted for as an asset acquisition, including an intangible asset for the assumed lease. The assumed lease terminated in the year ending December 31 2023. The net impact from the lease arrangement is recorded in other income, net on the consolidated statements of operations and was not material. The Company has broken ground on an expansion of its campus in Richmond, Virginia and acquired a small office building near the campus to facilitate employee staging while the expansion is being constructed. The capitalized spending associated with these efforts is recorded in the purchase and construction of Richmond assets line of the consolidated statements of cash flows.

Long-Lived Assets, Intangible Assets and Goodwill

Long-Lived Assets, Intangible Assets and Goodwill

Long-lived assets, such as property and equipment, and purchased intangibles subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company capitalizes interest on borrowings during the active construction period of major capital projects. Capitalized interest is added to the cost of the underlying asset and amortized over the estimated useful life of the asset. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset or asset group. If the carrying amount of an asset exceeds its estimated undiscounted future cash flows, an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset.

During 2022, the Company ceased using leased properties in California and Maryland as part of efforts to centralize its workforce, which resulted in an impairment charge of $9 million for lease ROU assets and property and equipment related to abandoned leases. The impairment was recorded in the general and administrative expense line of the consolidated statements of operations. The leases related to the North America segment.

Acquired technology and data, customer base assets, trade names and other intangible assets are related to the Company’s acquisitions. Acquired technology and data is amortized on a straight-line basis over periods ranging from 2 years to 7 years. Acquired intangible assets characterized as customer base assets consist of acquired customer contracts and the related customer relationships and are amortized over periods ranging from 3 years to 13 years. Acquired customer bases are amortized on an accelerated or straight-line basis depending on the expected economic benefit of the intangible asset. Acquired trade names and other intangible assets are amortized on a straight-line basis over periods ranging from 3 years to 15 years. The Company removes fully amortized intangible assets from the cost and accumulated amortization amounts disclosed.

Goodwill represents the future economic benefits arising from a business combination and is calculated as the excess of the purchase consideration paid in a business combination over the fair value of the net identifiable assets acquired. Goodwill is not amortized, but instead is assigned to each of the Company's reporting units and tested for impairment at least annually, on October 1, or more frequently if an event or other circumstance indicates that the fair value of a reporting unit may be below its carrying amount. The Company may first assess qualitative factors to evaluate whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or elect to bypass the qualitative assessment. If it is determined that it is more likely than not that the fair value of a reporting unit is less than its carrying value, or the Company elects to bypass the qualitative assessment, the Company then performs a quantitative assessment by determining the fair value of each reporting unit. The estimate of the fair value of each reporting unit is based on a projected discounted cash flow model that includes significant assumptions and estimates including the discount rate, growth rate and future financial performance. Assumptions about the discount rate are based on a weighted average cost of capital for comparable companies. Assumptions about the growth rate and future financial performance of a reporting unit are based on the Company's forecasts, business plans, economic projections and anticipated future cash flows. The fair value of each reporting unit is compared to the carrying amount of the reporting unit. If the carrying value of the reporting unit exceeds the fair value, then an impairment loss is recognized for the difference.

See Notes 5, 9 and 10 for further discussion of acquisitions, goodwill and intangible assets, respectively.

Debt Issuance Costs

Debt Issuance Costs

Costs incurred in connection with the issuance of long-term debt are deferred and amortized as interest expense over the term of the related debt using the effective interest method for term debt and on a straight-line basis for revolving debt. The Company made a policy election to classify deferred issuance costs on the revolving credit facility as a long-term asset on its consolidated balance sheets. Upon a refinancing or amendment, previously capitalized debt issuance costs are expensed and included in loss on extinguishment of debt if the Company determines that there has been a substantial modification of the related debt. If the Company determines that there has not been a substantial modification of the related debt, any previously capitalized debt issuance costs are amortized as interest expense over the term of the new debt instrument.

See Note 11 for further discussion of the Company's accounting for its outstanding debt, revolving credit facility and related issuance costs.

Business Combinations

Business Combinations

The Company includes the results of operations of the businesses that it acquires from the date of acquisition. The Company generally allocates the purchase consideration to the tangible assets acquired and liabilities assumed and intangible assets acquired based on their estimated fair values on the date of the acquisition. The purchase price is generally determined based on the fair value of the assets transferred, liabilities assumed and equity interests issued, after considering any transactions that are separate from the business combination. The excess of the fair value of purchase consideration over the fair values of these identifiable assets and liabilities is recorded as goodwill. The Company applies significant assumptions, estimates and judgments in determining the fair value of assets acquired and liabilities assumed on the acquisition date, especially with respect to intangible assets and contingent liabilities. Significant estimates in valuing certain intangible assets include, but are not limited to, future expected cash flows from acquired customer bases, acquired technology and acquired trade names, useful lives, royalty rates and discount rates. Estimates of fair value are based on assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. Any adjustments to provisional amounts that are identified during the measurement period, not to exceed one year from the date of acquisition, are recorded in the reporting period in which the adjustment amounts are determined. Upon the conclusion of the measurement period, any subsequent adjustments are recorded to earnings.

For a given acquisition, the Company may identify certain pre-acquisition contingencies as of the acquisition date and may extend its review and evaluation of these pre-acquisition contingencies throughout the measurement period in order to obtain sufficient information to assess whether the Company includes these contingencies as a part of the fair value estimates of assets acquired and liabilities assumed and, if so, to determine their estimated amounts.

If the Company cannot reasonably determine the fair value of a pre-acquisition contingency (non-income tax related) by the end of the measurement period, which is generally the case given the nature of such matters, the Company will recognize an asset or a liability for such pre-acquisition contingency if: (i) it is probable that an asset existed or a liability had been assumed at the acquisition date and (ii) the amount of the asset or liability can be reasonably estimated. Subsequent to the measurement period, changes in the Company's estimates of such contingencies will affect earnings and could have a material effect on its results of operations and financial position.

In addition, uncertain tax positions and tax-related valuation allowances assumed in connection with a business combination are initially estimated as of the acquisition date. The Company reevaluates these items based upon facts and circumstances that existed as of the acquisition date with any adjustments to its preliminary estimates being recorded to goodwill, provided that the Company is within the measurement period. Subsequent to the measurement period, changes to these uncertain tax positions and tax-related valuation allowances will affect the Company's provision for income taxes in its consolidated statements of operations and comprehensive income and could have a material impact on its results of operations and financial position.

Transaction costs associated with business combinations are expensed as incurred, and are included in general and administrative expenses in the consolidated statements of operations.

Recently Adopted and Not Yet Adopted Accounting Pronouncements

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In 2021, the Company adopted ASU 2021-08, Business Combinations (Topic 805), Accounting for Contract Assets and Contract Liabilities from Contracts with Customers. This guidance requires contract assets and liabilities acquired or assumed in an acquisition be measured in accordance with the accounting framework for revenue from contracts with customers as if the

Company had originated the acquired contract. This is an exception to the general requirement to measure assets acquired and liabilities assumed at their fair value on the acquisition date. The Company applied this revised guidance to all acquisitions in the year ended December 31, 2021. The application of this guidance to contract assets and contract liabilities acquired or assumed in connection with the Company's acquisitions for the year ended December 31, 2021 did not have a material impact on the Company's consolidated financial statements and related disclosures.

In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASC 848 contains optional expedients and exceptions for applying GAAP to debt, contracts, hedging relationships and other transactions affected by reference rate reform. The provisions of ASC 848 must be applied to all contracts that are accounted for under a Topic, Subtopic or Industry Subtopic for all transactions other than derivatives, which may be applied at a hedging relationship level. Originally, the guidance was effective for fiscal years beginning after January 1, 2021, including interim periods within those fiscal years. However, in response to the deferral of the cessation date for certain overnight LIBOR measures, the FASB issued ASU 2022-06 on December 21, 2022, which extends the sunset date of Topic 848 to December 31, 2024. The Company's 2020 Credit Agreement provides for a $750 million revolving credit facility and a letter of credit sublimit of $20 million, with interest rates previously benchmarked to LIBOR. The Company adopted this accounting pronouncement with the execution of the First Amendment to the 2020 Credit Agreement in May 2023. This guidance provides an optional practical expedient that allows a qualifying modification to be accounted for as a debt modification rather than be analyzed under existing guidance to determine if the modification should be accounted for as a debt extinguishment. In adopting this accounting standard, we have elected to apply this optional expedient. Adopting this accounting standard did not have a material impact on the Company's consolidated financial statements and related disclosures.

Recent Accounting Pronouncements Not Yet Adopted

In March 2022, the FASB issued ASU 2022-02, Financial Instruments-Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures. This ASU eliminates prior guidance on troubled debt restructurings for creditors that have adopted ASU 2016-13, Measurement of Credit Losses in Financial Statements, and adds enhanced disclosures for creditors with respect to loan refinancings and restructurings for borrowers experiencing financial difficulty. In addition, the ASU amends guidance on "vintage disclosures" to require the disclosure of current period gross write offs by year of origination. This guidance is effective for fiscal years beginning after December 15, 2022. The Company expects there to be no material impact on its consolidated financial statements and related disclosures from the adoption of this ASU.

In November 2023, the FASB issued ASU No. 2023-07 (Topic 280), Improvements to Reportable Segment Disclosures. The ASU primarily will require enhanced disclosures about significant segment expenses. Additionally, it requires disclosure of the title and position of the individual identified as the CODM and an explanation of how the CODM uses the reported measures of a segment’s profit or loss in assessing segment performance and deciding how to allocate resources. The ASU is effective for annual periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Adoption of the ASU should be applied retrospectively to all prior periods presented in the financial statements. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures.

In December 2023, the FASB issued ASU No. 2023-09 (Topic 740), Improvements to Income Tax Disclosures (Topic 740). The ASU requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as an expansion of other income tax disclosures. The ASU is effective on a prospective basis for annual reporting periods beginning after December 15, 2024. The Company is currently evaluating the impact this ASU will have on its consolidated financial statements and related disclosures.

Commitments and Contingencies

Currently, and from time to time, the Company is involved in litigation incidental to the conduct of its business. The Company records a provision for a liability when it is both probable that a liability has been incurred and the amount can be reasonably estimated. While it is reasonably possible that an unfavorable outcome may occur as a result of one or more of the Company’s current litigation matters, at this time management has concluded that the resolutions of these matters are not expected to have a material effect on the Company's consolidated financial position, future results of operations or liquidity. Legal defense costs are expensed as incurred.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of Accumulated Other Comprehensive Loss

The components of accumulated other comprehensive loss, net of tax, were as follows (in millions):

	As of December 31,
	2023		2022
Foreign currency translation loss	$	(17.6)	$	(29.1)
Total accumulated other comprehensive loss	$	(17.6)	$	(29.1)

Schedule of Stock-Based Compensation Expense for Stock Options and Restricted Stock

Stock-based compensation expense for stock options, restricted stock awards and restricted stock units issued under equity incentive plans, stock purchases under the ESPP, DSUs and Matching RSUs awarded under the MSPP included in the Company’s consolidated statements of operations were as follows (in millions):

	Year Ended December 31,
	2023		2022			2021
Cost of revenues	$	14.3	$	12.6		$	11.2
Selling and marketing (excluding customer base amortization)	9.1		7.8		7.8	6.3
Software development	17.5		13.0			12.5
General and administrative	44.1		41.8			33.7
Total stock-based compensation expense	$	85.0	$	75.2		$	63.7

Schedule of Property and Equipment

Depreciation and amortization are calculated on a straight-line basis over the following estimated useful lives of the assets:

Buildings	Twenty to thirty-nine years
Land	Indefinite
Aircrafts	Ten to twenty years
Furniture and office equipment	Five to ten years
Vehicles	Four to five years
Computer hardware and software	Three to five years
Leasehold improvements	Shorter of lease terms or useful life

Property and equipment consists of the following (in millions):

	December 31,
	2023		2022
Leasehold improvements	$	87.8	$	108.9
Furniture, office equipment and vehicles	73.4		52.6
Computer hardware and software	56.3		43.8
Aircrafts	44.2		44.2
Land	52.2		52.2
Buildings	263.8		105.1
Property and equipment, gross	577.7		406.8
Accumulated depreciation and amortization	(105.5)		(85.5)
Property and equipment, net	$	472.2	$	321.3

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REVENUE FROM CONTRACTS WITH CUSTOMERS (Tables)

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The Company provides information, analytics and online marketplaces to the commercial real estate industry, hospitality industry, residential industry and related professionals. Revenues by operating segment and type of service consist of the following (in millions):

	Year Ended December 31,
	2023						2022						2021
	North America		International		Total		North America		International		Total		North America		International		Total
CoStar	$	886.0	$	39.2	$	925.2	$	800.2	$	36.8	$	837.0	$	686.9	$	35.9	$	722.8
Information services	132.4		38.5		170.9		125.0		32.4		157.4		113.8		27.9		141.7
Multifamily	914.2		—		914.2		745.4		—		745.4		678.7		—		678.7
LoopNet	255.4		9.4		264.8		223.7		7.2		230.9		204.8		2.7		207.5
Residential	43.9		2.2		46.1		73.7		—		73.7		74.6		—		74.6
Other Marketplaces	133.8		—		133.8		138.0		—		138.0		118.8		—		118.8
Total revenues	$	2,365.7	$	89.3	$	2,455.0	$	2,106.0	$	76.4	$	2,182.4	$	1,877.6	$	66.5	$	1,944.1

Summary of Deferred Revenue and Contract Assets

Deferred revenue as of December 31, 2023 and 2022 was as follows (in millions):

		December 31,
Balance	Balance Sheet Caption	2023		2022
Current portion	Deferred revenue	$	104.2	$	103.6
Non-current portion	Lease and other long-term liabilities	0.1		0.2
Total deferred revenue		$	104.3	$	103.8

Changes in deferred revenue for the period were as follows (in millions):

Balance at December 31, 2022(1)	$	103.8
Revenue recognized in the current period from the amounts in the beginning balance	(103.8)
New deferrals, net of amounts recognized in the current period	103.4
Effects of foreign currency	0.9
Balance at December 31, 2023(2)	$	104.3
__________________________

(1) This balance includes $1.8 million of net new deferrals recognized in connection with business acquisitions made in 2022. See Note 5 for further discussion of acquisitions.

(2) This balance includes $1.0 million of net new deferrals recognized in connection with business acquisitions made in 2023. See Note 5 for further discussion of acquisitions.

Contract assets are generated when contractual billing schedules differ from revenue recognition timing and represent a conditional right to consideration for satisfied performance obligations that becomes a receivable when the conditions are satisfied. Contract assets as of December 31, 2023 and 2022 were as follows (in millions):

		December 31,
Balance	Balance Sheet Caption	2023		2022
Current portion	Prepaid expenses and other current assets	$	5.8	$	4.0
Non-current portion	Deposits and other assets	8.0		8.4
Total contract assets		$	13.8	$	12.4

Schedule of Commissions Expense

Commissions expense activity for the years ended December 31, 2023, 2022 and 2021, was as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Commissions incurred	$	173.5	$	162.1	$	117.3
Commissions capitalized in the current period	(120.2)		(116.8)		(72.0)
Amortization of deferred commissions costs	95.2		76.1		63.4
Total commissions expense	$	148.5	$	121.4	$	108.7

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ALLOWANCE FOR CREDIT LOSSES (Tables)

12 Months Ended

Dec. 31, 2023

Credit Loss [Abstract]

Schedule of Financing Receivable, Allowance for Credit Loss

The following tables detail the activity related to the allowance for credit losses for trade receivables by portfolio segment (in millions):

	Year Ended December 31, 2023
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2022	$	4.5	$	1.1	$	4.3	$	1.4	$	0.9	$	12.2
Current-period provision (release) for expected credit losses	22.1		1.4		4.9		6.0		0.6		35.0
Write-offs charged against the allowance, net of recoveries and other	(16.9)		—		(1.9)		(4.7)		(0.5)		(24.0)
Ending balance at December 31, 2023	$	9.7	$	2.5	$	7.3	$	2.7	$	1.0	$	23.2

-

	Year Ended December 31, 2022
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2021	$	5.4	$	1.8	$	3.4	$	2.0	$	0.8	$	13.4
Current-period provision (release) for expected credit losses	9.2		(0.6)		5.8		3.8		0.1		18.3
Write-offs charged against the allowance, net of recoveries and other	(10.1)		(0.1)		(4.9)		(4.4)		—		(19.5)
Ending balance at December 31, 2022	$	4.5	$	1.1	$	4.3	$	1.4	$	0.9	$	12.2

	Year Ended December 31, 2021
	CoStar		Information Services		Multifamily		LoopNet		Other Marketplaces		Total
Beginning balance at December 31, 2020	$	5.6	$	2.7	$	4.4	$	1.7	$	0.8	$	15.2
Current-period provision for expected credit losses	5.6		(0.4)		3.1		2.6		—		10.9
Write-offs charged against the allowance, net of recoveries and other	(5.8)		(0.5)		(4.1)		(2.3)		—		(12.7)
Ending balance at December 31, 2021	$	5.4	$	1.8	$	3.4	$	2.0	$	0.8	$	13.4

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ACQUISITIONS (Tables)

12 Months Ended

Dec. 31, 2023

Business Combination and Asset Acquisition [Abstract]

Schedule of Recognized Identified Assets Acquired and Liabilities Assumed

The following table summarized the amounts recorded for acquired assets and assumed liabilities recorded at their fair value as of the closing date of the acquisition (in millions):

	Preliminary: December 12, 2023
Cash and cash equivalents	$	18.2
Accounts receivable	2.3
Goodwill	62.8
Intangible assets	55.2
Accrued expenses	(12.7)
Accrued wages and commissions	(2.0)
Deferred income taxes, net	(3.0)
Other assets and liabilities	(0.4)
Fair value of identifiable net assets acquired	$	120.4

The following table summarizes the amounts recorded for acquired assets and assumed liabilities recorded at their fair values as of the acquisition date (in millions):

	Final: May 24, 2021
Cash and cash equivalents	$	—
Accounts receivable	1.8
Lease right-of-use assets	0.4
Goodwill	91.9
Intangible assets	53.4
Deferred income taxes, net	7.9
Lease liabilities	(0.4)
Deferred revenue	(1.5)
Other assets and liabilities	(1.3)
Fair value of identifiable net assets acquired	$	152.2

Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination

The following table summarizes the fair values (in millions) of the identifiable intangible assets acquired in the OnTheMarket Acquisition included in the Company's International operating segment, their related estimated useful lives (in years) and their respective amortization methods:

	Estimated Fair Value		Estimated Useful Life	Amortization Method
Customer base	$	42.0	8	Accelerated
Trade name	10.2		15	Straight-line
Technology	3.0		2	Straight-line
Total intangible assets	$	55.2

The following table summarizes the fair values (in millions) of the identifiable intangible assets acquired in the Homes.com Acquisition included in the Company's North America operating segment, their related estimated useful lives (in years) and their respective amortization methods:

	Estimated Fair Value		Estimated Useful Life	Amortization Method
Customer base	$	32.0	8	Accelerated
Trade name	21.0		15	Straight-line
Technology	0.4		2	Straight-line
Total intangible assets	$	53.4

Business Acquisition, Pro Forma Information

The unaudited pro forma financial information presented below reflects the consolidated results of operations of the Company assuming the OnTheMarket Acquisition had taken place on January 1, 2022 and was as follows (in millions, except per share data):

	Year Ended December 31,
	2023		2022
Revenue	$	2,494.0	$	2,224.3
Net income	$	371.9	$	361.9
Net income per share - basic	$	0.91	$	0.91
Net income per share - diluted	$	0.91	$	0.91

The impact of the OnTheMarket Acquisition on the Company's revenue and net income in the consolidated statements of operations from December 12, 2023 through December 31, 2023 was not material.

and was as follows (in millions, except per share data):

	Year Ended December 31,
	2021
Revenue	$	1,962.1
Net income	$	286.7
Net income per share - basic	$	0.74
Net income per share - diluted	$	0.73

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LEASES (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Components of Lease Expense

Lease costs related to the Company's operating and finance leases included in the consolidated statements of operations were as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Operating lease costs:
Cost of revenues	$	10.0	$	8.4	$	10.1
Software development	6.3		7.2		6.9
Selling and marketing (excluding customer base amortization)	15.4		12.6		11.9
General and administrative	4.0		5.4		5.9
Total operating lease costs	35.7		33.6		34.8
Finance lease costs:
Amortization of ROU assets	0.8		—		—
Interest on lease liabilities	0.2		—		—
Total finance lease costs	1.0		—		—
Total lease costs	$	36.7	$	33.6	$	34.8

Supplemental Balance Sheet Information Related to Leases

Supplemental balance sheet information related to operating leases was as follows ($ in millions):

		Year Ended December 31,
Balance	Balance Sheet Location	2023			2022
Operating lease liabilities		$	109.9		$	118.3
Less: imputed interest		(7.0)			(6.2)
Present value of lease liabilities		102.9			112.1
Less: current portion of lease liabilities	Lease liabilities	36.9			36.0
Long-term lease liabilities	Lease and other long-term liabilities	$	66.0		$	76.1
Weighted-average remaining lease term in years		3.9			3.6
Weighted-average discount rate		3.6		%	3.1		%
ROU Assets	Lease right-of-use assets	$	79.8		$	80.4
Finance lease liabilities		$	14.6		$	—
Less: imputed interest		(1.6)			—
Present value of lease liabilities		13.0			—
Less: current portion of lease liabilities	Lease liabilities	3.1			—
Long-term lease liabilities	Lease and other long-term liabilities	$	9.9		$	—
Weighted-average remaining lease term in years		3.8			0
Weighted-average discount rate		7.8		%	—		%
ROU Assets	Property and equipment, net	$	10.8		$	—

Schedule of Supplemental Cash Flow Information for Leases

Supplemental cash flow information related to leases was as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used in operating leases	$	44.9	$	41.6	$	37.3
Operating cash flows used in finance leases	$	0.2	$	—	$	—
Financing cash flows used in finance leases	$	0.7	$	—	$	—
ROU assets obtained in exchange for lease new obligations:
Operating leases	$	29.1	$	20.0	$	34.2
Finance leases	$	13.6	$	—	$	—

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PROPERTY AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Schedule of Property and Equipment

Depreciation and amortization are calculated on a straight-line basis over the following estimated useful lives of the assets:

Buildings	Twenty to thirty-nine years
Land	Indefinite
Aircrafts	Ten to twenty years
Furniture and office equipment	Five to ten years
Vehicles	Four to five years
Computer hardware and software	Three to five years
Leasehold improvements	Shorter of lease terms or useful life

Property and equipment consists of the following (in millions):

	December 31,
	2023		2022
Leasehold improvements	$	87.8	$	108.9
Furniture, office equipment and vehicles	73.4		52.6
Computer hardware and software	56.3		43.8
Aircrafts	44.2		44.2
Land	52.2		52.2
Buildings	263.8		105.1
Property and equipment, gross	577.7		406.8
Accumulated depreciation and amortization	(105.5)		(85.5)
Property and equipment, net	$	472.2	$	321.3

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GOODWILL (Tables)

12 Months Ended

Dec. 31, 2023

Goodwill [Abstract]

Schedule of Goodwill

The changes in the carrying amount of goodwill by operating segment consist of the following (in millions):

	North America		International		Total
Goodwill, December 31, 2021	$	2,145.8	$	175.2	$	2,321.0
Acquisitions, including measurement period adjustments(1)	3.4		7.1		10.5
Effect of foreign currency translation	—		(16.7)		(16.7)
Goodwill, December 31, 2022	2,149.2		165.6		2,314.8
Acquisitions, including measurement period adjustments	—		62.8		62.8
Effect of foreign currency translation	—		8.6		8.6
Goodwill, December 31, 2023	$	2,149.2	$	237.0	$	2,386.2
__________________________

(1) North America goodwill recorded during the year ended December 31, 2022 relates to a measurement period adjustment for income taxes for Homes.com of $3.4 million. International goodwill recorded in connection with the Business Immo Acquisition was $7.1 million.

(2) International goodwill generated during the year ended December 31, 2023 from the OnTheMarket Acquisition was $62.8 million.

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INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2023

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Schedule of Acquired Finite-Lived Intangible Assets by Major Class

Intangible assets consist of the following (in millions, except amortization period data):

	December 31,				Weighted- Average Amortization Period (in years)
	2023		2022
Acquired technology and data	$	36.3	$	40.4	5
Accumulated amortization	(21.0)		(20.7)
Acquired technology and data, net	15.3		19.7
Acquired customer base	509.5		464.2		10
Accumulated amortization	(330.7)		(287.0)
Acquired customer base, net	178.8		177.2
Acquired trade names and other intangible assets	258.9		247.4		13
Accumulated amortization	(139.3)		(115.0)
Acquired trade names and other intangible assets, net	119.6		132.4
Intangible assets, net	$	313.7	$	329.3

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LONG-TERM DEBT (Tables)

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

The table below presents the components of outstanding debt (in millions):

	December 31,
	2023		2022
2.800% Senior Notes due July 15, 2030	$	1,000.0	$	1,000.0
2020 Credit Agreement, due July 1, 2025	—		—
Total face amount of long-term debt	1,000.0		1,000.0
Senior Notes unamortized discount and issuance costs	(9.5)		(10.8)
Long-term debt, net	$	990.5	$	989.2

Schedule of Interest Expense

For the years ended December 31, 2023, 2022 and 2021, the Company recognized interest expense as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Interest on outstanding borrowings	$	28.0	$	28.0	$	28.0
Amortization of Senior Notes discount and issuance costs	2.4		2.3		2.3
Interest capitalized for construction in process	(1.6)		—		—
Commitment fees and other	2.6		2.0		2.0
Total interest expense	$	31.4	$	32.3	$	32.3

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INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense

The components of the provision for income taxes attributable to operations consist of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
Current:
Federal	$	126.3	$	116.3	$	61.3
State	36.6		31.2		24.6
Foreign	0.9		0.7		1.3
Total current	163.8		148.2		87.2
Deferred:
Federal	(31.7)		(20.4)		22.9
State	(2.9)		(9.6)		8.5
Foreign	(2.6)		(1.2)		(7.2)
Total deferred	(37.2)		(31.2)		24.2
Total provision for income taxes	$	126.6	$	117.0	$	111.4

Schedule of Deferred Tax Assets and Liabilities

The components of deferred tax assets and liabilities consist of the following (in millions):

	December 31,
	2023		2022
Deferred tax assets:
Allowance for credit losses	$	5.8	$	3.4
Accrued compensation	11.9		4.6
Stock compensation	15.3		20.4
Net operating losses	34.7		26.8
Accrued reserve and other	5.8		6.7
Lease liabilities	21.8		26.4
Capitalized research and development costs	92.4		45.4
Research and development credits	4.5		6.1
Total deferred tax assets, prior to valuation allowance	192.2		139.8
Valuation allowance	(9.0)		(5.2)
Total deferred tax assets, net of valuation allowance	183.2		134.6
Deferred tax liabilities:
Deferred commission costs, net	(42.3)		(36.1)
Lease right-of-use assets	(16.0)		(18.2)
Prepaid expenses	(4.1)		(3.2)
Property and equipment, net	(25.1)		(25.8)
Intangible assets, net	(128.1)		(117.8)
Total deferred tax liabilities	(215.6)		(201.1)
Net deferred tax liabilities	$	(32.4)	$	(66.5)

Schedule of Effective Income Tax Rate Reconciliation

The Company’s provision for income taxes resulted in effective tax rates that varied from the statutory federal income tax rate as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Expected federal income tax provision at statutory rate	$	105.3	$	102.1	$	84.8
State income taxes, net of federal benefit	27.4		21.5		21.0
Increase (decrease) in valuation allowance	1.9		(0.5)		(5.0)
Research credits	(20.2)		(17.5)		(13.1)
Excess tax benefit	(5.9)		(1.8)		(10.9)
Tax reserves	4.2		1.5		(12.8)
Nondeductible compensation	8.8		11.4		10.4
International restructuring	0.1		(3.9)		34.9
Other adjustments	5.0		4.2		2.1
Income tax expense	$	126.6	$	117.0	$	111.4

Schedule of Unrecognized Tax Benefits

The following table summarizes the activity related to the Company’s unrecognized tax benefits (in millions):

Unrecognized tax benefit as of December 31, 2020	$	28.9
Increase for current year tax positions	3.1
Decrease for prior year tax positions	(5.4)
Decrease for settlements with taxing authorities	(9.9)
Expiration of the statute of limitation for assessment of taxes	(1.9)
Unrecognized tax benefit as of December 31, 2021	14.8
Increase for current year tax positions	3.4
Increase for prior year tax positions	0.3
Expiration of the statute of limitation for assessment of taxes	(2.3)
Unrecognized tax benefit as of December 31, 2022	16.2
Increase for current year tax positions	4.4
Increase for prior year tax positions	1.7
Expiration of the statute of limitation for assessment of taxes	(2.4)
Unrecognized tax benefit as of December 31, 2023	$	19.9

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COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Lessee, Operating Lease, Liability, Maturity

The following summarizes the Company's significant contractual obligations, including related payments due by period, as of December 31, 2023 (in millions):

Year Ending December 31,	Operating lease obligations		Finance lease obligations		Long-term debt principal payments		Long-term debt principal interest payments
2024	$	39.0	$	3.9	$	—	$	28.0
2025	25.4		3.9		—		28.0
2026	15.1		3.9		—		28.0
2027	13.1		2.9		—		28.0
2028	10.7		—		—		28.0
Thereafter	6.6		—		1,000.0		56.0
Total	$	109.9	$	14.6	$	1,000.0	$	196.0

Schedule of Maturities of Long-term Debt

The following summarizes the Company's significant contractual obligations, including related payments due by period, as of December 31, 2023 (in millions):

Year Ending December 31,	Operating lease obligations		Finance lease obligations		Long-term debt principal payments		Long-term debt principal interest payments
2024	$	39.0	$	3.9	$	—	$	28.0
2025	25.4		3.9		—		28.0
2026	15.1		3.9		—		28.0
2027	13.1		2.9		—		28.0
2028	10.7		—		—		28.0
Thereafter	6.6		—		1,000.0		56.0
Total	$	109.9	$	14.6	$	1,000.0	$	196.0

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SEGMENT REPORTING (Tables)

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Summarized EBITDA Information by Operating Segment

Summarized EBITDA information by operating segment consists of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
North America	$	403.0	$	577.3	$	557.1
International	(13.2)		5.4		7.9
Total EBITDA	$	389.8	$	582.7	$	565.0

Reconciliation of Net Income to EBITDA

The reconciliation of net income to EBITDA consists of the following (in millions):

	Year Ended December 31,
	2023		2022		2021
Net income	$	374.7	$	369.5	$	292.6
Amortization of acquired intangible assets in cost of revenues	31.5		29.0		28.8
Amortization of acquired intangible assets in operating expenses	42.2		73.6		74.8
Depreciation and other amortization	33.8		29.1		29.1
Interest (income) expense, net	(213.6)		(32.1)		31.6
Other (income), net	(5.4)		(3.4)		(3.3)
Income tax expense	126.6		117.0		111.4
EBITDA	$	389.8	$	582.7	$	565.0

Summarized Information by Operating Segment, Assets and Liabilities

Summarized information by operating segment consists of the following (in millions):

	December 31,
	2023		2022
Property and equipment, net
North America	$	465.7	$	320.3
International	6.5		1.0
Total property and equipment, net	$	472.2	$	321.3
Goodwill
North America	$	2,149.2	$	2,149.2
International	237.0		165.6
Total goodwill	$	2,386.2	$	2,314.8
Assets
North America	$	8,505.5	$	8,146.3
International	414.2		256.2
Total assets	$	8,919.7	$	8,402.5
Liabilities
North America	$	1,499.7	$	1,486.3
International	81.4		46.2
Total liabilities	$	1,581.1	$	1,532.5

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NET INCOME PER SHARE (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Calculation of Basic and Diluted Net Income (Loss) Per Share

The following table sets forth the calculation of basic and diluted net income per share (in millions, except per share data):

	Year Ended December 31,
	2023		2022		2021
Numerator:
Net income	$	374.7	$	369.5	$	292.6
Denominator:
Denominator for basic net income per share — weighted-average outstanding shares	405.3		396.3		392.2
Effect of dilutive securities:
Stock options, restricted stock awards and restricted stock units	1.6		1.5		2.0
Denominator for diluted net income per share — weighted-average outstanding shares	406.9		397.8		394.2
Net income per share — basic	$	0.92	$	0.93	$	0.75
Net income per share — diluted	$	0.92	$	0.93	$	0.74

Schedule of Anti-Dilutive Securities Excluded From Computation of Earnings Per Share

The following table summarizes the shares underlying the unvested performance-based restricted stock and anti-dilutive securities excluded from the basic and diluted earnings per share calculations (in millions):

	Year Ended December 31,
	2023	2022	2021
Performance-based restricted stock awards	0.2	0.4	0.4
Anti-dilutive securities	0.7	1.0	0.4

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EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2023

Compensation Related Costs [Abstract]

Schedule of Option Activity

Option activity was as follows:

	Number of Shares	Range of Exercise Price	Weighted- Average Exercise Price		Weighted- Average Remaining Contract Life (in years)	Aggregate Intrinsic Value (in millions)
Outstanding at December 31, 2020	2,023,100	$10.22 - $66.65	$	34.18	6.99	$	117.8
Granted	159,000	$91.98	$	91.98
Exercised	(206,000)	$20.49 - $39.82	$	30.78
Outstanding at December 31, 2021	1,976,100	$10.22 - $91.98	$	39.18	6.24	$	80.8
Granted	202,100	$67.29	$	67.29
Exercised	—
Canceled or expired	—
Outstanding at December 31, 2022	2,178,200	$10.22 - $91.98	$	41.79	5.60	$	79.6
Granted	140,800	$76.78	$	76.78
Exercised	(419,340)	$10.22 - $34.21	$	17.77
Canceled or expired	—
Outstanding at December 31, 2023	1,899,660	$20.49 - $91.98	$	49.69	5.53	$	72.4
Exercisable at December 31, 2021	1,473,420	$10.22 - $66.65	$	29.55	5.59	$	72.9
Exercisable at December 31, 2022	1,766,070	$10.22 - $91.98	$	34.40	4.96	$	76.5
Exercisable at December 31, 2023	1,571,105	$20.49 - $91.98	$	44.32	4.93	$	68.1

Fair Value Assumption for Options Granted

The Company estimated the fair value of each option granted on the date of grant using the Black-Scholes option-pricing model, using the assumptions in the following table:

	Year Ended December 31,
	2023			2022			2021
Dividend yield	0		%	0		%	0		%
Expected volatility	35		%	31		%	30		%
Risk-free interest rate	3.96		%	1.89		%	0.56		%
Expected life (in years)	5			5			5
Weighted-average grant date fair value	$	28.87		$	20.43		$	25.09

The assumptions used to estimate the fair value of awards with both a performance and a market condition were as follows:

	Year Ended December 31,
	2023			2022			2021
Dividend yield	0		%	0		%	0		%
Expected volatility	37		%	34		%	42		%
Risk-free interest rate	4.31		%	1.71		%	0.20		%
Expected life (in years)	3			3			3
Weighted-average grant date fair value	$	81.58		$	71.19		$	99.73

Summarized Information Regarding Options Outstanding

The following table summarizes information regarding options outstanding at December 31, 2023:

	Options Outstanding				Options Exercisable
Range of Exercise Price	Number of Shares	Weighted-Average Remaining Contractual Life (in years)	Weighted- Average Exercise Price		Number of Shares	Weighted- Average  Exercise Price
$20.49 - $27.35	346,000	3.16	$	20.49	346,000	$	20.49
$27.36 - $37.02	354,090	4.16	$	34.21	354,090	$	34.21
$37.03 - $53.24	385,670	5.10	$	39.82	385,670	$	39.82
$53.25 - $66.97	312,000	6.10	$	66.65	312,000	$	66.65
$66.98 - $91.98	501,900	8.09	$	77.77	173,345	$	82.39
	1,899,660	5.53	$	49.69	1,571,105	$	44.32

Unvested Restricted Stock Awards Activity

The following table presents unvested restricted stock awards activity for the year ended December 31, 2023:

	Restricted Stock Awards — without Market Condition			Restricted Stock Awards — with Market Condition
	Number of Shares	Weighted-Average Grant Date Fair Value per Share		Number of Shares	Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock awards at December 31, 2022	2,061,894	$	67.15	620,880	$	80.55
Granted	1,096,446	$	73.27	283,440	$	81.58
Vested	(787,883)	$	66.51	(90,408)	$	72.69
Canceled	(230,546)	$	68.58	(132,792)	$	72.69
Unvested restricted stock awards at December 31, 2023	2,139,911	$	70.38	681,120	$	83.56

The following table presents unvested restricted stock units activity for the year ended December 31, 2023:

	Number of Units	Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock units at December 31, 2022	21,560	$	65.24
Granted	10,465	$	70.74
Vested	(8,129)	$	65.77
Canceled	(977)	$	68.34
Unvested restricted stock units at December 31, 2023	22,919	$	67.43

The following tables presents the Matching RSU activity for the year ended December 31, 2023:

	Number of Matching RSU Shares	Weighted-Average Grant Date Fair Value per Share
Unvested MSPP restricted stock units at December 31, 2022	180,431	$	60.52
Granted	82,374	$	67.36
Vested	(52,710)	$	46.91
Canceled	(13,128)	$	66.67
Unvested MSPP restricted stock units at December 31, 2023	196,967	$	66.61

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ORGANIZATION (Details)	12 Months Ended
	Dec. 31, 2023 operating_segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Term of subscription-based license agreements	1 year
Number of business segments	2

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Revenue Recognition) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Term of subscription-based license agreements	1 year
Percentage of total revenue	95.00%	93.00%	93.00%
Amortization period of deferred sales commissions	3 years

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Foreign Currency Translation and Accumulated Other Comprehensive Loss) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Foreign currency transaction gain (loss), realized	$ 3,000,000	$ 1,400,000	$ (300,000)
Accumulated Other Comprehensive Income (Loss) Net of Tax [Abstract]
Foreign currency translation loss	(17,600,000)	(29,100,000)
Total accumulated other comprehensive loss	(17,600,000)	(29,100,000)
Reclassification out of accumulated other comprehensive loss	$ 0	$ 0

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Advertising Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Advertising costs	$ 549.6	$ 305.7	$ 312.0

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Stock-Based Compensation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 85.0	$ 75.2	$ 63.7
Cost of revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	14.3	12.6	11.2
Selling and marketing (excluding customer base amortization)
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	9.1	7.8	6.3
Software development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	17.5	13.0	12.5
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 44.1	$ 41.8	$ 33.7

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Cash Reconciliation) (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 5,200,000,000	$ 5,000,000,000
Restricted cash	$ 0	$ 0

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Allowance for Credit Losses) (Details)	Dec. 31, 2023 numberOfReceivable portfolioSegment
Accounting Policies [Abstract]
Number of portfolio segments | portfolioSegment	5
Number of classes of trade receivables based on location	2
Number of trade receivables in information services portfolio	4
Number of trade receivables in multifamily portfolio	1
Number of trade receivables in loopnet portfolio	1
Number of trade receivables in other marketplaces portfolio segment	2

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Property and Equipment) (Details) - USD ($) $ in Millions	1 Months Ended
	Jan. 31, 2021	Dec. 31, 2023
Office Building - Richmond, Virginia
Property, Plant and Equipment [Line Items]
Purchase price	$ 131
Minimum | Buildings
Property, Plant and Equipment [Line Items]
Useful life		20 years
Minimum | Aircrafts
Property, Plant and Equipment [Line Items]
Useful life		10 years
Minimum | Furniture and office equipment
Property, Plant and Equipment [Line Items]
Useful life		5 years
Minimum | Vehicles
Property, Plant and Equipment [Line Items]
Useful life		4 years
Minimum | Computer hardware and software
Property, Plant and Equipment [Line Items]
Useful life		3 years
Maximum | Buildings
Property, Plant and Equipment [Line Items]
Useful life		39 years
Maximum | Aircrafts
Property, Plant and Equipment [Line Items]
Useful life		20 years
Maximum | Furniture and office equipment
Property, Plant and Equipment [Line Items]
Useful life		10 years
Maximum | Vehicles
Property, Plant and Equipment [Line Items]
Useful life		5 years
Maximum | Computer hardware and software
Property, Plant and Equipment [Line Items]
Useful life		5 years

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Long-Lived Assets, Intangible Assets and Goodwill) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
North America
Finite-Lived Intangible Assets [Line Items]
Impairment loss	$ 9,000
Acquired Technology | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life	2 years
Acquired Technology | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life	7 years
Acquired customer base | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life	3 years
Acquired customer base | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life	13 years
Trade name | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful life	3 years
Trade name | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful life	15 years

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Recent Accounting Pronouncements) (Details) - 2020 Credit Agreement - USD ($) $ in Millions	Dec. 31, 2023	Jul. 01, 2020
Revolving Loans and Letters of Credit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Line of credit facility, amount outstanding		$ 750
Revolving credit sub-facility for swing-line loans and issuances of letters of credit		750
Letter of Credit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revolving credit sub-facility for swing-line loans and issuances of letters of credit	$ 250	$ 20

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REVENUE FROM CONTRACTS WITH CUSTOMERS (Disaggregated Revenue) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 2,455.0	$ 2,182.4	$ 1,944.1
CoStar
Disaggregation of Revenue [Line Items]
Revenues	925.2	837.0	722.8
Information services
Disaggregation of Revenue [Line Items]
Revenues	170.9	157.4	141.7
Multifamily
Disaggregation of Revenue [Line Items]
Revenues	914.2	745.4	678.7
LoopNet
Disaggregation of Revenue [Line Items]
Revenues	264.8	230.9	207.5
Residential
Disaggregation of Revenue [Line Items]
Revenues	46.1	73.7	74.6
Other Marketplaces
Disaggregation of Revenue [Line Items]
Revenues	133.8	138.0	118.8
North America
Disaggregation of Revenue [Line Items]
Revenues	2,365.7	2,106.0	1,877.6
North America | CoStar
Disaggregation of Revenue [Line Items]
Revenues	886.0	800.2	686.9
North America | Information services
Disaggregation of Revenue [Line Items]
Revenues	132.4	125.0	113.8
North America | Multifamily
Disaggregation of Revenue [Line Items]
Revenues	914.2	745.4	678.7
North America | LoopNet
Disaggregation of Revenue [Line Items]
Revenues	255.4	223.7	204.8
North America | Residential
Disaggregation of Revenue [Line Items]
Revenues	43.9	73.7	74.6
North America | Other Marketplaces
Disaggregation of Revenue [Line Items]
Revenues	133.8	138.0	118.8
International
Disaggregation of Revenue [Line Items]
Revenues	89.3	76.4	66.5
International | CoStar
Disaggregation of Revenue [Line Items]
Revenues	39.2	36.8	35.9
International | Information services
Disaggregation of Revenue [Line Items]
Revenues	38.5	32.4	27.9
International | Multifamily
Disaggregation of Revenue [Line Items]
Revenues	0.0	0.0	0.0
International | LoopNet
Disaggregation of Revenue [Line Items]
Revenues	9.4	7.2	2.7
International | Residential
Disaggregation of Revenue [Line Items]
Revenues	2.2	0.0	0.0
International | Other Marketplaces
Disaggregation of Revenue [Line Items]
Revenues	$ 0.0	$ 0.0	$ 0.0

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REVENUE FROM CONTRACTS WITH CUSTOMERS (Deferred Revenue) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Current portion	$ 104.2	$ 103.6
Non-current portion	0.1	0.2
Total deferred revenue	$ 104.3	$ 103.8

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REVENUE FROM CONTRACTS WITH CUSTOMERS (Contract Assets and Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Change in Contract with Customer, Liability [Roll Forward]
Beginning balance	$ 103.8
Revenue recognized in the current period from the amounts in the beginning balance	(103.8)
New deferrals, net of amounts recognized in the current period	103.4
Effects of foreign currency	0.9
Ending balance	104.3
New deferrals recognized in connection with business acquisitions made	$ 1.0	$ 1.8

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REVENUE FROM CONTRACTS WITH CUSTOMERS (Contract Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Current portion	$ 5.8	$ 4.0
Non-current portion	8.0	8.4
Total contract assets	13.8	12.4
Recenue recognized as contract asset	$ 1.4	$ 3.2

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REVENUE FROM CONTRACTS WITH CUSTOMERS (Commissions) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Deferred sales commissions of impaired	$ 0	$ 0
Commissions incurred	173,500,000	162,100,000	$ 117,300,000
Commissions capitalized in the current period	(120,200,000)	(116,800,000)	(72,000,000.0)
Amortization of deferred commissions costs	95,200,000	76,100,000	63,400,000
Total commissions expense	$ 148,500,000	$ 121,400,000	$ 108,700,000

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REVENUE FROM CONTRACTS WITH CUSTOMERS (Unsatisfied Performance Obligations) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Revenue from Contract with Customer [Abstract]
Remaining performance obligation	$ 409.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	5 years

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ALLOWANCE FOR CREDIT LOSSES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 12.2	$ 13.4	$ 15.2
Current-period provision (release) for expected credit losses	35.0	18.3	10.9
Write-offs charged against the allowance, net of recoveries and other	(24.0)	(19.5)	(12.7)
Ending balance	23.2	12.2	13.4
CoStar
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4.5	5.4	5.6
Current-period provision (release) for expected credit losses	22.1	9.2	5.6
Write-offs charged against the allowance, net of recoveries and other	(16.9)	(10.1)	(5.8)
Ending balance	9.7	4.5	5.4
Information services
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1.1	1.8	2.7
Current-period provision (release) for expected credit losses	1.4	(0.6)	(0.4)
Write-offs charged against the allowance, net of recoveries and other	0.0	(0.1)	(0.5)
Ending balance	2.5	1.1	1.8
Multifamily
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	4.3	3.4	4.4
Current-period provision (release) for expected credit losses	4.9	5.8	3.1
Write-offs charged against the allowance, net of recoveries and other	(1.9)	(4.9)	(4.1)
Ending balance	7.3	4.3	3.4
LoopNet
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1.4	2.0	1.7
Current-period provision (release) for expected credit losses	6.0	3.8	2.6
Write-offs charged against the allowance, net of recoveries and other	(4.7)	(4.4)	(2.3)
Ending balance	2.7	1.4	2.0
Other Marketplaces
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	0.9	0.8	0.8
Current-period provision (release) for expected credit losses	0.6	0.1	0.0
Write-offs charged against the allowance, net of recoveries and other	(0.5)	0.0	0.0
Ending balance	$ 1.0	$ 0.9	$ 0.8

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ACQUISITIONS (Narrative) (Details) £ / shares in Units, € in Millions, £ in Millions, $ in Millions						1 Months Ended			3 Months Ended	7 Months Ended	12 Months Ended
	Dec. 12, 2023 USD ($)	Dec. 12, 2023 GBP (£)	Oct. 01, 2021 USD ($)	Oct. 01, 2021 EUR (€)	May 24, 2021 USD ($)	Dec. 31, 2023 USD ($)	Apr. 30, 2022 USD ($)	Apr. 30, 2022 EUR (€)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2023 GBP (£)	Dec. 12, 2023 £ / shares	May 31, 2021 USD ($)
Business Acquisition [Line Items]
Cash paid for acquisitions, net											$ 99.6	$ 6.3	$ 193.0
OnTheMarket
Business Acquisition [Line Items]
Goodwill, expected tax deductible amount						$ 0.0					0.0
Transaction costs						11.0					11.0
Intangible assets	$ 55.2
Fair value of identifiable net assets acquired	120.4
OnTheMarket | North America
Business Acquisition [Line Items]
Goodwill acquired						62.8
Business Immo
Business Acquisition [Line Items]
Goodwill acquired							$ 7.1
Cash paid for acquisitions, net							6.3	€ 5.8
Intangible assets							$ 3.9
BureauxLocaux
Business Acquisition [Line Items]
Aggregate purchase price			$ 40.6	€ 35.0
Goodwill acquired									$ 27.4
Intangible assets									$ 18.3	$ 18.3			$ 18.3
Homes.com
Business Acquisition [Line Items]
Goodwill, expected tax deductible amount					$ 20.0
Intangible assets					53.4
Purchase price before adjustments																$ 150.0
Fair value of identifiable net assets acquired					152.2											$ 152.2
Business combinations cash escrow payment employee compensation post combination											5.0
Business combination tax liabilities accrual amount						6.6					6.6
Increase in revenue										13.6
Decrease in net income										$ 23.5
Homes.com | North America
Business Acquisition [Line Items]
Goodwill acquired					$ 91.9
OnTheMarket plc
Business Acquisition [Line Items]
Share price of acquisition (in pound per share) | £ / shares															£ 1.10
Payment for acquisition	117.9	£ 94.0
Liabilities incurred	2.6	2.0
Aggregate purchase price	$ 120.4	£ 96.0
Consideration payable						$ 5.1					$ 5.1			£ 4.0

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ACQUISITIONS (Schedule of Recognized Identified Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 12, 2023	Dec. 31, 2022	Dec. 31, 2021	May 31, 2021	May 24, 2021
Business Acquisition [Line Items]
Goodwill	$ 2,386.2		$ 2,314.8	$ 2,321.0
Deferred income taxes, net	$ (1.0)		$ (1.8)
OnTheMarket
Business Acquisition [Line Items]
Cash and cash equivalents		$ 18.2
Accounts receivable		2.3
Goodwill		62.8
Intangible assets		55.2
Accrued expenses		(12.7)
Accrued wages and commissions		(2.0)
Deferred income taxes, net		(3.0)
Other assets and liabilities		(0.4)
Fair value of identifiable net assets acquired		$ 120.4
Homes.com
Business Acquisition [Line Items]
Cash and cash equivalents						$ 0.0
Accounts receivable						1.8
Lease right-of-use assets						0.4
Goodwill						91.9
Intangible assets						53.4
Deferred income taxes, net						7.9
Lease liabilities						(0.4)
Deferred revenue						(1.5)
Other assets and liabilities						(1.3)
Fair value of identifiable net assets acquired					$ 152.2	$ 152.2

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ACQUISITIONS (Intangible Assets Acquired) (Details) - USD ($) $ in Millions		1 Months Ended
	May 24, 2021	Dec. 31, 2023
OnTheMarket
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value		$ 55.2
OnTheMarket | Customer base
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value		$ 42.0
Estimated Useful Life		8 years
OnTheMarket | Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value		$ 10.2
Estimated Useful Life		15 years
OnTheMarket | Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value		$ 3.0
Estimated Useful Life		2 years
Homes.com
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 53.4
Homes.com | Customer base
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 32.0
Estimated Useful Life	8 years
Homes.com | Trade name
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 21.0
Estimated Useful Life	15 years
Homes.com | Technology
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Fair Value	$ 0.4
Estimated Useful Life	2 years

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ACQUISITIONS (Business Acquisition, Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Combination and Asset Acquisition [Abstract]
Revenue	$ 2,494.0	$ 2,224.3	$ 1,962.1
Net income	$ 371.9	$ 361.9	$ 286.7
Net income per share - basic (usd per share)	$ 0.91	$ 0.91	$ 0.74
Net income per share - diluted (usd per share)	$ 0.91	$ 0.91	$ 0.73

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ACQUISITIONS (Pro Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Combination and Asset Acquisition [Abstract]
Revenue	$ 2,494.0	$ 2,224.3	$ 1,962.1
Net income	$ 371.9	$ 361.9	$ 286.7
Net income per share - basic (usd per share)	$ 0.91	$ 0.91	$ 0.74
Net income per share - diluted (usd per share)	$ 0.91	$ 0.91	$ 0.73

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INVESTMENTS AND FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Billions	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Inputs, Level 2
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Debt outstanding, fair value	$ 0.9	$ 0.8
Cash Equivalents | Fair Value, Inputs, Level 1
Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 5.1	$ 4.8

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LEASES (Narrative) (Details)	Dec. 31, 2023
Maximum
Lessee, Lease, Description [Line Items]
Term of contract	8 years

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LEASES (Lease Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating lease costs:
Total operating lease costs	$ 35.7	$ 33.6	$ 34.8
Finance lease costs:
Amortization of ROU assets	0.8	0.0	0.0
Interest on lease liabilities	0.2	0.0	0.0
Total finance lease costs	1.0	0.0	0.0
Total lease costs	36.7	33.6	34.8
Cost of revenues
Operating lease costs:
Total operating lease costs	10.0	8.4	10.1
Software development
Operating lease costs:
Total operating lease costs	6.3	7.2	6.9
Selling and marketing (excluding customer base amortization)
Operating lease costs:
Total operating lease costs	15.4	12.6	11.9
General and administrative
Operating lease costs:
Total operating lease costs	$ 4.0	$ 5.4	$ 5.9

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LEASES (Supplemental Balance Sheet Information Related to Leases) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease liabilities	$ 109.9	$ 118.3
Less: imputed interest	(7.0)	(6.2)
Present value of lease liabilities	102.9	112.1
Less: current portion of lease liabilities	36.9	36.0
Long-term lease liabilities	$ 66.0	$ 76.1
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Lease liabilities	Lease liabilities
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Lease and other long-term liabilities	Lease and other long-term liabilities
Weighted-average remaining lease term in years	3 years 10 months 24 days	3 years 7 months 6 days
Weighted-average discount rate	3.60%	3.10%
Lease right-of-use assets	$ 79.8	$ 80.4
Finance lease liabilities	14.6	0.0
Less: imputed interest	(1.6)	0.0
Present value of lease liabilities	$ 13.0	$ 0.0
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Lease liabilities	Lease liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Lease and other long-term liabilities	Lease and other long-term liabilities
Less: current portion of lease liabilities	$ 3.1	$ 0.0
Long-term lease liabilities	$ 9.9	$ 0.0
Weighted-average remaining lease term in years	3 years 9 months 18 days	0 years
Weighted-average discount rate	7.80%	0.00%
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property and equipment, net	Property and equipment, net
ROU Assets	$ 10.8	$ 0.0

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LEASES (Supplemental Cash Flow Information Related to Leases) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used in operating leases	$ 44.9	$ 41.6	$ 37.3
Operating cash flows used in finance leases	0.2	0.0	0.0
Financing cash flows used in finance leases	0.7	0.0	0.0
ROU assets obtained in exchange for lease new obligations:
Operating leases	29.1	20.0	34.2
Finance leases	$ 13.6	$ 0.0	$ 0.0

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PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2022	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 406.8	$ 577.7	$ 406.8
Accumulated depreciation and amortization		(85.5)	(105.5)	(85.5)
Property and equipment, net		321.3	472.2	321.3
Depreciation expense for property and equipment			33.8	29.1	$ 29.0
Depreciated assets written-off			14.1	27.6
Proceeds from sale of property and equipment and other assets			0.0	30.1	$ 0.6
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross		108.9	87.8	108.9
Furniture, office equipment and vehicles
Property, Plant and Equipment [Line Items]
Property and equipment, gross		52.6	73.4	52.6
Computer hardware and software
Property, Plant and Equipment [Line Items]
Property and equipment, gross		43.8	56.3	43.8
Aircrafts
Property, Plant and Equipment [Line Items]
Property and equipment, gross		44.2	44.2	44.2
Proceeds from sale of property and equipment and other assets	$ 24.9
Gain (loss) on disposition of assets		3.3
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross		52.2	52.2	52.2
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 105.1	$ 263.8	$ 105.1

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GOODWILL (Goodwill by Segment) (Details) - USD ($) $ in Millions		1 Months Ended		12 Months Ended
	May 24, 2021	Dec. 31, 2023	Apr. 30, 2022	Dec. 31, 2023	Dec. 31, 2022
Goodwill [Roll Forward]
Goodwill, beginning balance				$ 2,314.8	$ 2,321.0
Acquisitions, including measurement period adjustments				62.8	10.5
Effect of foreign currency translation				8.6	(16.7)
Goodwill, ending balance		$ 2,386.2		2,386.2	2,314.8
Homes.com
Goodwill [Roll Forward]
Goodwill, ending balance	$ 91.9
Business Immo
Goodwill [Roll Forward]
Goodwill acquired			$ 7.1
North America
Goodwill [Roll Forward]
Goodwill, beginning balance				2,149.2	2,145.8
Acquisitions, including measurement period adjustments				0.0	3.4
Effect of foreign currency translation				0.0	0.0
Goodwill, ending balance		2,149.2		2,149.2	2,149.2
North America | Homes.com
Goodwill [Roll Forward]
Goodwill acquired	$ 91.9
Goodwill measuring period adjustment					3.4
North America | OnTheMarket
Goodwill [Roll Forward]
Goodwill acquired		62.8
International
Goodwill [Roll Forward]
Goodwill, beginning balance				165.6	175.2
Acquisitions, including measurement period adjustments				62.8	7.1
Effect of foreign currency translation				8.6	(16.7)
Goodwill, ending balance		$ 237.0		237.0	165.6
International | Business Immo
Goodwill [Roll Forward]
Goodwill acquired					$ 7.1
International | OnTheMarket
Goodwill [Roll Forward]
Goodwill acquired				$ 62.8

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GOODWILL (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Goodwill, impairment	$ 0	$ 0	$ 0
2022 Acquisitions
Goodwill [Line Items]
Goodwill, expected tax deductible amount		$ 0

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INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	$ 313.7	$ 329.3
Acquired technology and data
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	36.3	40.4
Accumulated amortization	(21.0)	(20.7)
Finite-lived intangible assets, net	$ 15.3	19.7
Weighted- Average Amortization Period (in years)	5 years
Acquired customer base
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 509.5	464.2
Accumulated amortization	(330.7)	(287.0)
Finite-lived intangible assets, net	$ 178.8	177.2
Weighted- Average Amortization Period (in years)	10 years
Acquired trade names and other intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 258.9	247.4
Accumulated amortization	(139.3)	(115.0)
Finite-lived intangible assets, net	$ 119.6	$ 132.4
Weighted- Average Amortization Period (in years)	13 years

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INTANGIBLE ASSETS (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 73,700,000	$ 102,600,000	$ 103,600,000
Indefinite-lived intangible assets, written off	7,400,000	87,700,000	171,000,000
Amortization expense for 2024	70,800,000
Amortization expense for 2025	54,800,000
Amortization expense for 2026	43,300,000
Amortization expense for 2027	34,700,000
Amortization expense for 2028	30,800,000
Impairment of intangible assets	0	0	0
Customer base amortization	42,200,000	$ 73,600,000	$ 74,800,000
Acquired customer base
Acquired Finite-Lived Intangible Assets [Line Items]
Customer base amortization	$ 16,300,000

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LONG-TERM DEBT (Schedule of Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Jul. 01, 2020
Debt Instrument [Line Items]
Total face amount of long-term debt	$ 1,000.0	$ 1,000.0
Senior Notes unamortized discount and issuance costs	(9.5)	(10.8)
Long-term debt, net	990.5	989.2
2.800% Senior Notes
Debt Instrument [Line Items]
Stated interest rate			2.80%
Total face amount of long-term debt	1,000.0	1,000.0	$ 1,000.0
2020 Credit Agreement
Debt Instrument [Line Items]
Total face amount of long-term debt	$ 0.0	$ 0.0

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LONG-TERM DEBT (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
	Jul. 01, 2020	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total face amount of long-term debt		$ 1,000.0	$ 1,000.0
2.800% Senior Notes
Debt Instrument [Line Items]
Total face amount of long-term debt	$ 1,000.0	1,000.0	1,000.0
Stated interest rate	2.80%
Discounted rate par value	99.921%
Redemption price rate	100.00%
2020 Credit Agreement
Debt Instrument [Line Items]
Total face amount of long-term debt		$ 0.0	0.0
Total leverage ratio		4.50
2020 Credit Agreement | Other Assets
Debt Instrument [Line Items]
Debt issuance costs, net		$ 1.6	$ 2.7
2020 Credit Agreement | Revolving Loans and Letters of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 750.0
Term of credit facility	5 years
2020 Credit Agreement | Revolving Loans and Letters of Credit | Minimum
Debt Instrument [Line Items]
Commitment fee percentage	0.25%
2020 Credit Agreement | Revolving Loans and Letters of Credit | Maximum
Debt Instrument [Line Items]
Commitment fee percentage	0.30%
2020 Credit Agreement | Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 20.0	$ 250.0
2020 Credit Agreement | Letter of Credit | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread		0.00%
2020 Credit Agreement | Letter of Credit | Adjustment to SOFR
Debt Instrument [Line Items]
Basis spread		0.10%
2020 Credit Agreement | Letter of Credit | Minimum | Alternate Base Rate
Debt Instrument [Line Items]
Basis spread		0.50%
2020 Credit Agreement | Letter of Credit | Minimum | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread		1.50%
2020 Credit Agreement | Letter of Credit | Maximum | Alternate Base Rate
Debt Instrument [Line Items]
Basis spread		1.25%
2020 Credit Agreement | Letter of Credit | Maximum | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread		2.25%

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LONG-TERM DEBT (Interest) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Amortization of Senior Notes discount and issuance costs	$ 2.4	$ 2.3	$ 2.3
Interest capitalized for construction in process	(1.6)	0.0	0.0
Commitment fees and other	2.6	2.0	2.0
Total interest expense	31.4	32.3	32.3
Interest on outstanding borrowings
Debt Instrument [Line Items]
Total interest expense	$ 28.0	$ 28.0	$ 28.0

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INCOME TAXES (Components for Provision for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 126.3	$ 116.3	$ 61.3
State	36.6	31.2	24.6
Foreign	0.9	0.7	1.3
Total current	163.8	148.2	87.2
Deferred:
Federal	(31.7)	(20.4)	22.9
State	(2.9)	(9.6)	8.5
Foreign	(2.6)	(1.2)	(7.2)
Total deferred	(37.2)	(31.2)	24.2
Total provision for income taxes	$ 126.6	$ 117.0	$ 111.4

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INCOME TAXES (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Allowance for credit losses	$ 5.8	$ 3.4
Accrued compensation	11.9	4.6
Stock compensation	15.3	20.4
Net operating losses	34.7	26.8
Accrued reserve and other	5.8	6.7
Lease liabilities	21.8	26.4
Capitalized research and development costs	92.4	45.4
Research and development credits	4.5	6.1
Total deferred tax assets, prior to valuation allowance	192.2	139.8
Valuation allowance	(9.0)	(5.2)
Total deferred tax assets, net of valuation allowance	183.2	134.6
Deferred tax liabilities:
Deferred commission costs, net	(42.3)	(36.1)
Lease right-of-use assets	(16.0)	(18.2)
Prepaid expenses	(4.1)	(3.2)
Property and equipment, net	(25.1)	(25.8)
Intangible assets, net	(128.1)	(117.8)
Total deferred tax liabilities	(215.6)	(201.1)
Net deferred tax liabilities	$ (32.4)	$ (66.5)

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INCOME TAXES (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Increase (decrease) in valuation allowance	$ 3.8	$ (0.5)
Income from U.S. sources	526.7	493.2	$ 408.8
Income from foreign sources	25.4	6.7	4.8
Cash tax benefits resulting in net operating loss carryforward	5.9	12.6	14.1
Unrecognized tax benefits	19.9	16.2
Increase for current year tax positions	4.4	3.4	3.1
Decrease for prior year tax positions	1.7		5.4
Expiration of the statute of limitation for assessment of taxes	2.4	2.3	1.9
Income tax penalties and interest expense (reversal)	0.7	0.1	0.4
Interest and penalties accrued on income taxes	1.4	$ 0.7	$ 0.6
Foreign Country
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	77.3
Domestic Country
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	71.3
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Net operating loss carryforward	0.4
Income tax credit carryforward	$ 8.0

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INCOME TAXES (Reconciliation of Provision for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective tax rate reconciliation [Abstract]
Expected federal income tax provision at statutory rate	$ 105.3	$ 102.1	$ 84.8
State income taxes, net of federal benefit	27.4	21.5	21.0
Increase (decrease) in valuation allowance	1.9	(0.5)	(5.0)
Research credits	(20.2)	(17.5)	(13.1)
Excess tax benefit	(5.9)	(1.8)	(10.9)
Tax reserves	4.2	1.5	(12.8)
Nondeductible compensation	8.8	11.4	10.4
International restructuring	0.1	(3.9)	34.9
Other adjustments	5.0	4.2	2.1
Total provision for income taxes	$ 126.6	$ 117.0	$ 111.4

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INCOME TAXES (Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits beginning balance	$ 16.2	$ 14.8	$ 28.9
Increase for current year tax positions	4.4	3.4	3.1
Increase for prior year tax positions	1.7	0.3
Decrease for prior year tax positions	(1.7)		(5.4)
Decrease for settlements with taxing authorities			(9.9)
Expiration of the statute of limitation for assessment of taxes	(2.4)	(2.3)	(1.9)
Unrecognized tax benefits ending balance	$ 19.9	$ 16.2	$ 14.8

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COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Operating lease obligations
2024	$ 39.0
2025	25.4
2026	15.1
2027	13.1
2028	10.7
Thereafter	6.6
Operating lease liabilities	109.9	$ 118.3
Finance lease obligations
2024	3.9
2025	3.9
2026	3.9
2027	2.9
2028	0.0
Thereafter	0.0
Finance lease liabilities	14.6	$ 0.0
Long-term debt principal payments
2024	0.0
2025	0.0
2026	0.0
2027	0.0
2028	0.0
Thereafter	1,000.0
Total	1,000.0
Long-term debt principal interest payments
2024	28.0
2025	28.0
2026	28.0
2027	28.0
2028	28.0
Thereafter	56.0
Total	$ 196.0

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SEGMENT REPORTING (Narrative) (Details)	12 Months Ended
	Dec. 31, 2023 operating_segment
Segment Reporting [Abstract]
Number of operating segments	2

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SEGMENT REPORTING (EBITDA) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total EBITDA	$ 389.8	$ 582.7	$ 565.0
Operating Segments | North America
Segment Reporting Information [Line Items]
Total EBITDA	403.0	577.3	557.1
Operating Segments | International
Segment Reporting Information [Line Items]
Total EBITDA	$ (13.2)	$ 5.4	$ 7.9

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SEGMENT REPORTING (Reconciliation of Net Income (Loss) to EBITDA) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting [Abstract]
Net income	$ 374.7	$ 369.5	$ 292.6
Amortization of acquired intangible assets in cost of revenues	31.5	29.0	28.8
Amortization of acquired intangible assets in operating expenses	42.2	73.6	74.8
Depreciation and other amortization	33.8	29.1	29.1
Interest (income) expense, net	(213.6)	(32.1)	31.6
Other (income), net	(5.4)	(3.4)	(3.3)
Income tax expense	126.6	117.0	111.4
EBITDA	$ 389.8	$ 582.7	$ 565.0

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SEGMENT REPORTING (Summarized Information) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Property and equipment, net	$ 472.2	$ 321.3
Goodwill	2,386.2	2,314.8	$ 2,321.0
Total assets	8,919.7	8,402.5
Total liabilities	1,581.1	1,532.5
North America
Segment Reporting Information [Line Items]
Goodwill	2,149.2	2,149.2	2,145.8
International
Segment Reporting Information [Line Items]
Goodwill	237.0	165.6	$ 175.2
Operating Segments | North America
Segment Reporting Information [Line Items]
Property and equipment, net	465.7	320.3
Goodwill	2,149.2	2,149.2
Total assets	8,505.5	8,146.3
Total liabilities	1,499.7	1,486.3
Operating Segments | International
Segment Reporting Information [Line Items]
Property and equipment, net	6.5	1.0
Goodwill	237.0	165.6
Total assets	414.2	256.2
Total liabilities	$ 81.4	$ 46.2

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STOCKHOLDERS' EQUITY (Details) $ / shares in Units, $ in Millions	Sep. 20, 2022 USD ($) $ / shares shares	Jun. 07, 2021 $ / shares shares	May 28, 2020 USD ($) $ / shares shares	Dec. 31, 2023 $ / shares shares	Dec. 31, 2022 $ / shares shares	Jun. 06, 2021 shares
Preferred stock
Preferred stock authorized for issuance (in shares)				2,000,000	2,000,000
Preferred stock, par value (in dollars per share) | $ / shares				$ 0.01	$ 0.01
Common stock
Common stock authorized for issuance (in shares)				1,200,000,000	1,200,000,000
Common stock, par or stated value per share (in dollars per share) | $ / shares		$ 0.01		$ 0.01	$ 0.01
Subsidiary, Sale of Stock [Line Items]
Preferred stock authorized for issuance (in shares)				2,000,000	2,000,000
Preferred stock, par value (in dollars per share) | $ / shares				$ 0.01	$ 0.01
Common stock authorized for issuance (in shares)				1,200,000,000	1,200,000,000
Common stock, par or stated value per share (in dollars per share) | $ / shares		$ 0.01		$ 0.01	$ 0.01
Conversion ratio		10
Dividends common stock, shares (in shares)		9
Board of Directors
Common stock
Common stock authorized for issuance (in shares)		1,200,000,000				60,000,000
Subsidiary, Sale of Stock [Line Items]
Common stock authorized for issuance (in shares)		1,200,000,000				60,000,000
Public Offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares)	10,700,000		26,300,000
Sale of stock, price per share (usd per share) | $ / shares	$ 70.38		$ 65.50
Consideration received on transaction | $	$ 745.7		$ 1,700.0
Payments of stock issuance costs | $	$ 4.3		$ 35.0

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NET INCOME PER SHARE (Details) $ / shares in Units, shares in Millions, $ in Millions		12 Months Ended
	Jun. 07, 2021	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares
Numerator:
Net income | $		$ 374.7	$ 369.5	$ 292.6
Denominator:
Denominator for basic net income per share — weighted-average outstanding shares		405.3	396.3	392.2
Effect of dilutive securities:
Stock options, restricted stock awards and restricted stock units (in shares)		1.6	1.5	2.0
Denominator for diluted net income per share — weighted-average outstanding shares (in shares)		406.9	397.8	394.2
Net income per share — basic (in dollars per share) | $ / shares		$ 0.92	$ 0.93	$ 0.75
Net income per share — diluted (in dollars per share) | $ / shares		$ 0.92	$ 0.93	$ 0.74
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		0.7	1.0	0.4
Conversion ratio	10
Performance-based restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		0.2	0.4	0.4

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EMPLOYEE BENEFIT PLANS (Stock Incentive Plans - Narrative) (Details) $ in Millions		12 Months Ended
	Jun. 07, 2021	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Jun. 09, 2016 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion ratio	10
Tax benefit from stock-based compensation		$ 6.8	$ 0.0	$ 2.4
Compensation expense		$ 85.0	75.2	63.7
CoStar Group, Inc. 2007 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant under the plan (in shares) | shares					0
CoStar Group, Inc. 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant under the plan (in shares) | shares		13,400,000
Shares of common stock authorized for issuance under the plan (in shares) | shares		22,700,000
CoStar Group, Inc. 2016 Stock Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of options and restricted stock grants		3 years
CoStar Group, Inc. 2016 Stock Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of options and restricted stock grants		4 years
Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of options and restricted stock grants		1 year
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost expected to be recognized in future years		$ 115.3
Weighted-average-period expected to recognize the unrecognized compensation cost (in years)		2 years 4 months 24 days
Aggregate intrinsic value of options exercised		$ 24.3	0.0	11.0
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of options and restricted stock grants		3 years
Performance service period		3 years
Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement, award vesting rights, percentage		80.00%
Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement, award vesting rights, percentage		120.00%
Performance-based RSAs - with Market Condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost expected to be recognized in future years		$ 14.0
Compensation expense		$ 13.6	$ 11.9	$ 8.0
Granted (in shares) | shares		283,440
DSU
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of options and restricted stock grants		4 years
Deferred stock unit, granted percentage		100.00%
Granted (in shares) | shares		82,374	75,479

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EMPLOYEE BENEFIT PLANS (Stock Option Activity) (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Jun. 07, 2021	Dec. 31, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Conversion ratio	10
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period (in shares) | shares		2,178,200	1,976,100	2,023,100
Granted (in shares) | shares		140,800	202,100	159,000
Exercised (in shares) | shares		(419,340)	0	(206,000)
Canceled or expired (in shares) | shares		0	0
Outstanding at end of period (in shares) | shares		1,899,660	2,178,200	1,976,100	2,023,100
Exercisable at end of period (in shares) | shares		1,571,105	1,766,070	1,473,420
Share Based Compensation Exercisable Range [Abstract]
Granted (dollars per share)		$ 76.78	$ 67.29	$ 91.98
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Outstanding at beginning of period (in dollars per share)		41.79	39.18	34.18
Granted (in dollars per share)		76.78	67.29	91.98
Exercised (in dollars per share)		17.77		30.78
Outstanding at end of period (in dollars per share)		49.69	41.79	39.18	$ 34.18
Exercisable at end of period (in dollars per share)		$ 44.32	$ 34.40	$ 29.55
Weighted average remaining contract life, outstanding		5 years 6 months 10 days	5 years 7 months 6 days	6 years 2 months 26 days	6 years 11 months 26 days
Weighted average remaining contract life, outstanding, exercisable		4 years 11 months 4 days	4 years 11 months 15 days	5 years 7 months 2 days
Aggregate intrinsic value of options outstanding at end of period | $		$ 72.4	$ 79.6	$ 80.8	$ 117.8
Aggregate intrinsic value of options exercisable at end of period | $		$ 68.1	$ 76.5	$ 72.9
Minimum
Share Based Compensation Exercisable Range [Abstract]
Outstanding (dollars per share)		$ 10.22	$ 10.22
Exercised (dollars per share)		10.22		$ 20.49
Outstanding (dollars per share)		20.49	10.22	10.22
Minimum | Stock Options
Share Based Compensation Exercisable Range [Abstract]
Outstanding (dollars per share)				10.22
Outstanding (dollars per share)					$ 10.22
Exercisable at end of period (dollars per share)		20.49	10.22	10.22
Maximum | Stock Options
Share Based Compensation Exercisable Range [Abstract]
Outstanding (dollars per share)		91.98	91.98	66.65
Exercised (dollars per share)		34.21		39.82
Outstanding (dollars per share)		91.98	91.98	91.98	$ 66.65
Exercisable at end of period (dollars per share)		$ 91.98	$ 91.98	$ 66.65

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EMPLOYEE BENEFIT PLANS (Assumptions) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Expected volatility	35.00%	31.00%	30.00%
Risk-free interest rate	3.96%	1.89%	0.56%
Expected life (in years)	5 years	5 years	5 years
Weighted-average grant date fair value (in USD per share)	$ 28.87	$ 20.43	$ 25.09
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Expected volatility	37.00%	34.00%	42.00%
Risk-free interest rate	4.31%	1.71%	0.20%
Expected life (in years)	3 years	3 years	3 years
Weighted-average grant date fair value (in USD per share)	$ 81.58	$ 71.19	$ 99.73

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EMPLOYEE BENEFIT PLANS (Information Regarding Stock Options) (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Options Outstanding
Number of shares (in shares) | shares	1,899,660
Weighted-average remaining contractual life (in years)	5 years 6 months 10 days
Weighted- average exercise price (in dollars per share)	$ 49.69
Options Exercisable
Number of shares (in shares) | shares	1,571,105
Weighted-average exercise price (in dollars per share)	$ 44.32
$20.49 - $27.35
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise price, minimum, (in dollars per share)	20.49
Range of exercise price, maximum, (in dollars per share)	$ 27.35
Options Outstanding
Number of shares (in shares) | shares	346,000
Weighted-average remaining contractual life (in years)	3 years 1 month 28 days
Weighted- average exercise price (in dollars per share)	$ 20.49
Options Exercisable
Number of shares (in shares) | shares	346,000
Weighted-average exercise price (in dollars per share)	$ 20.49
$27.36 - $37.02
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise price, minimum, (in dollars per share)	27.36
Range of exercise price, maximum, (in dollars per share)	$ 37.02
Options Outstanding
Number of shares (in shares) | shares	354,090
Weighted-average remaining contractual life (in years)	4 years 1 month 28 days
Weighted- average exercise price (in dollars per share)	$ 34.21
Options Exercisable
Number of shares (in shares) | shares	354,090
Weighted-average exercise price (in dollars per share)	$ 34.21
$37.03 - $53.24
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise price, minimum, (in dollars per share)	37.03
Range of exercise price, maximum, (in dollars per share)	$ 53.24
Options Outstanding
Number of shares (in shares) | shares	385,670
Weighted-average remaining contractual life (in years)	5 years 1 month 6 days
Weighted- average exercise price (in dollars per share)	$ 39.82
Options Exercisable
Number of shares (in shares) | shares	385,670
Weighted-average exercise price (in dollars per share)	$ 39.82
$53.25 - $66.97
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise price, minimum, (in dollars per share)	53.25
Range of exercise price, maximum, (in dollars per share)	$ 66.97
Options Outstanding
Number of shares (in shares) | shares	312,000
Weighted-average remaining contractual life (in years)	6 years 1 month 6 days
Weighted- average exercise price (in dollars per share)	$ 66.65
Options Exercisable
Number of shares (in shares) | shares	312,000
Weighted-average exercise price (in dollars per share)	$ 66.65
$66.98 - $91.98
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of exercise price, minimum, (in dollars per share)	66.98
Range of exercise price, maximum, (in dollars per share)	$ 91.98
Options Outstanding
Number of shares (in shares) | shares	501,900
Weighted-average remaining contractual life (in years)	8 years 1 month 2 days
Weighted- average exercise price (in dollars per share)	$ 77.77
Options Exercisable
Number of shares (in shares) | shares	173,345
Weighted-average exercise price (in dollars per share)	$ 82.39

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EMPLOYEE BENEFIT PLANS (Restrictive Stock Award Activity) (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Performance Based RSAs Without Market Condition
Number of Shares
Unvested restricted stock at beginning of period (in shares) | shares	2,061,894
Granted (in shares) | shares	1,096,446
Vested (in shares) | shares	(787,883)
Canceled (in shares) | shares	(230,546)
Unvested restricted stock at end of period (in shares) | shares	2,139,911
Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock at beginning of period (in USD per share) | $ / shares	$ 67.15
Granted (in USD per share) | $ / shares	73.27
Vested (in USD per share) | $ / shares	66.51
Canceled (in USD per share) | $ / shares	68.58
Unvested restricted stock at end of period (in USD per share) | $ / shares	$ 70.38
Performance-based RSAs - with Market Condition
Number of Shares
Unvested restricted stock at beginning of period (in shares) | shares	620,880
Granted (in shares) | shares	283,440
Vested (in shares) | shares	(90,408)
Canceled (in shares) | shares	(132,792)
Unvested restricted stock at end of period (in shares) | shares	681,120
Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock at beginning of period (in USD per share) | $ / shares	$ 80.55
Granted (in USD per share) | $ / shares	81.58
Vested (in USD per share) | $ / shares	72.69
Canceled (in USD per share) | $ / shares	72.69
Unvested restricted stock at end of period (in USD per share) | $ / shares	$ 83.56

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EMPLOYEE BENEFIT PLANS (Restrictive Stock Units) (Details) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Number of Shares
Unvested restricted stock at beginning of period (in shares) | shares	21,560
Granted (in shares) | shares	10,465
Vested (in shares) | shares	(8,129)
Canceled (in shares) | shares	(977)
Unvested restricted stock at end of period (in shares) | shares	22,919
Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock at beginning of period (in USD per share) | $ / shares	$ 65.24
Granted (in USD per share) | $ / shares	70.74
Vested (in USD per share) | $ / shares	65.77
Canceled (in USD per share) | $ / shares	68.34
Unvested restricted stock at end of period (in USD per share) | $ / shares	$ 67.43

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EMPLOYEE BENEFIT PLANS (MSU and DSU Activity) (Details) - MSPP RSUs	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Number of Matching RSU Shares
Unvested restricted stock at beginning of period (in shares) | shares	180,431
Granted (in shares) | shares	82,374
Vested (in shares) | shares	52,710
Canceled (in shares) | shares	(13,128)
Unvested restricted stock at end of period (in shares) | shares	196,967
Weighted-Average Grant Date Fair Value per Share
Unvested restricted stock at beginning of period (in USD per share) | $ / shares	$ 60.52
Granted (in USD per share) | $ / shares	67.36
Vested (in USD per share) | $ / shares	46.91
Canceled (in USD per share) | $ / shares	66.67
Unvested restricted stock at end of period (in USD per share) | $ / shares	$ 66.61

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EMPLOYEE BENEFIT PLANS (Employee 401(k) Plan, Employee Pension Plan, Registered Retirement Savings Plan and Employee Stock Purchase Plan) (Details) - USD ($)		12 Months Ended
	Jun. 02, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Maximum percentage of employee total compensation matched by employer (in hundredths)		100.00%	100.00%	100.00%
Maximum annual employee contribution		4.00%	4.00%	4.00%
Company match to employee contributions		$ 25,500,000	$ 21,500,000	$ 17,600,000
Administrative expense		$ 0	$ 0	$ 0
Percentage of purchase price of company's common stock to the market price		90.00%
Increase in shares of common stock issued pursuant to stock plan (in shares)	1,000,000
Shares available, employee stock purchase plan (in shares)		782,328	1,010,267
Shares of company's common stock purchased during the period (in shares)		227,939	223,596
Registered Retirement Savings Plan
Defined Contribution Plan Disclosure [Line Items]
Maximum percentage of employee total compensation matched by employer (in hundredths)		100.00%	100.00%	100.00%
Maximum annual employee contribution		4.00%	4.00%	4.00%
Company match to employee contributions		$ 200,000	$ 100,000	$ 100,000
Foreign Plan | Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Maximum percentage of employee total compensation matched by employer (in hundredths)		6.00%	6.00%	6.00%
Company match to employee contributions		$ 1,200,000	$ 1,000,000	$ 900,000

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SUBSEQUENT EVENTS (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Feb. 21, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Subsequent Event [Line Items]
Payments for land and building		$ 117.5	$ 35.2	$ 123.7
Subsequent Event | Land and Building
Subsequent Event [Line Items]
Payments for land and building	$ 340.0