This prospectus supplement relates to shares of common stock of Upland Software, Inc. Our common stock is listed on The NASDAQ Global Market under the symbol "UPLD." The last reported sale price on The NASDAQ Global Market on May 8, 2019, was $44.29 per share.

We have granted the underwriters a 30-day option to purchase up to 495,000 additional shares from us at the public offering price, less the underwriting discounts and commissions.

We are an "emerging growth company" as defined by the Jumpstart Our Business Startups Act of 2012 and, as such, we have elected to comply with certain reduced public company reporting requirements for this prospectus supplement and future filings.

Investing in our common stock involves risks. See "Risk Factors" beginning on page S-9.

Neither the Securities and Exchange Commission, any state securities commission nor any other regulatory body has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

You should rely only on the information contained in this document or to which we have referred you. Neither we nor the Underwriters have authorized anyone to provide you with information that is different. This document may only be used where it is legal to sell these securities. The information in this document may only be accurate on the date of this document. Regardless of the time of delivery of this prospectus or of any sale of shares of our common stock and the information in any free writing prospectus that we may provide you in connection with this offering is accurate only as of the date of that free writing prospectus. Our business, financial condition, results of operations and future growth prospects may have changed since those dates.

This document is in two parts. The first part is this prospectus supplement, which adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into the accompanying prospectus. The second part is the accompanying prospectus, which gives more general information, some of which may not apply to this offering. This prospectus supplement adds, updates and changes information contained in the accompanying prospectus and the information incorporated by reference. To the extent the information contained in this prospectus supplement differs from the information contained in the accompanying prospectus or any document incorporated by reference, the information in this prospectus supplement shall control. This prospectus does not contain all of the information included in the registration statement. For a more complete understanding of the offering of the securities, you should refer to the registration statement, including its exhibits. The registration statement containing this prospectus, including the exhibits to the registration statement, provides additional information about us and the securities offered under this prospectus. You should read this prospectus supplement and the accompanying prospectus and related exhibits filed with the SEC together with additional information described under the heading "Where You Can Find More Information" and "Incorporation by Reference" before making your investment decision.

Unless the context otherwise requires, references in this prospectus supplement to "Upland," "we," "us" and "our" refer to Upland Software, Inc.

This prospectus supplement and the accompanying prospectus contain and incorporate by reference "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. When used in this prospectus supplement and the accompanying prospectus, the words "expects," "believes," "anticipates," "estimates," "may," "could," "intends," and similar expressions are intended to identify forward-looking statements. These statements are subject to known and unknown risks and uncertainties that could cause actual results to differ materially from those projected or otherwise implied by the forward-looking statements. These forward-looking statements speak only as of the date of this prospectus supplement. Given these risks and uncertainties, you should not place undue reliance on these forward-looking statements. We will discuss many of these risks and uncertainties in greater detail in this prospectus supplement under the heading "Risk Factors." Additional cautionary statements or discussions of risks and uncertainties that could affect our results or the achievement of the expectations described in forward-looking statements may also be contained in the documents we incorporate by reference into this prospectus supplement. These forward-looking statements speak only as of the date of this prospectus supplement. We expressly disclaim any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in our expectations with regard thereto or any change in events, conditions or circumstances on which any such statement is based. You should, however, review additional disclosures we make in our most recent Annual Report on Form 10-K, any subsequent Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K filed with the SEC and incorporated by reference.

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights selected information appearing elsewhere or incorporated by reference in this prospectus supplement and the accompanying prospectus and does not contain all of the information that may be important to you. This prospectus supplement and the accompanying prospectus include or incorporate by reference information about the shares we are offering as well as information regarding our business and detailed financial data. You should carefully read this prospectus supplement, the accompanying prospectus and the information incorporated by reference into this prospectus supplement and the accompanying prospectus in their entirety, including especially the "Risk Factors" section, as well as the documents to which we have referred you under "Where You Can Find More Information" below, before making an investment decision.

Overview of Our Company

Upland provides cloud-based enterprise work management software that enables organizations to plan, manage and execute projects and work. Our software applications address enterprise work challenges in the following enterprise solution categories:

Customer Experience Management. Upland Customer Experience Management, or CXM, solutions enable organizations to manage customer relationships across multiple channels—including email, short message service, or SMS, multimedia messaging service, or MMS, web, social, and mobile apps. Our products within this solution suite include Upland Mobile Messaging, Rant & Rave, Adestra, and RightAnswers.

Sales Enablement. Upland Sales Enablement solutions enable sales organizations to automate delivery of processes, sales activities, content, systems, and metrics at multiple stages of the sales process. Our products within this solution suite include Qvidian, RO Innovation, and LeadLander.

Professional Services Automation. Upland Professional Services Automation, or PSA, solutions enable service organizations to manage professional services delivery and related functions. Our products within this solution suite include Tenrox, RightAnswers, FileBound, RO Innovation, and Qvidian.

Project and Financial Management. Upland Project and Financial Management solutions enable enterprises to manage project portfolios and track, analyze and manage information technology, or IT, cloud, and telecom spending. Our products within this solution suite include PowerSteering, Eclipse PPM, RightAnswers, and ComSci.

Enterprise Knowledge Management. Upland Enterprise Knowledge Management, or KM, solutions enable knowledge-sharing across different departments within an enterprise. Our products within this solution suite include RightAnswers, Tenrox, and PowerSteering.

Secure Document Services. Upland Secure Document Services solutions enable enterprises to manage and automate document intensive business processes with data security through scan and fax platforms, data monitoring and breach prevention capabilities, and the automated routing of content to its final destination. Our products within this solution suite include AccuRoute, FileBound, and InterFAX.

Document Lifecycle Automation. Upland Document Lifecycle solutions enable users to digitize, organize, automate, integrate, analyze and optimize high volume processes. Our products within this solution suite include AccuRoute, FileBound, Qvidian, and RO Innovation.

Our customers currently use our applications in the following functional areas:

Project Management. Business leaders and Project Management Offices, or PMOs, use our applications to optimize project portfolios, balance capacity against demand, improve

financial-based decision making, align execution of projects to strategy across large organizations, and manage the entire project delivery lifecycle. Our applications are designed to deliver value to project management across a variety of use cases including continuous improvement, enterprise IT, new product development, and services departments along with industry depth in higher education, public sector, and healthcare IT.

Information Technology. IT departments use our applications to manage a variety of IT activities and resources across the enterprise. Our applications help information technology departments better ensure they are delivering against the objectives of the business by helping them select and prioritize the right investments, gain greater control of resource demand and allocation, and track and report benefit realization. Our applications enable executives to gain better insight into IT spending to help prevent cost overruns and understand the nature of consumption.

Business Operations. Different functional departments use our applications to streamline operations and accelerate business performance across their value chain. Our solutions in this area range from supply chain collaboration and factory management, back office document and vendor management, to applications designed to improve sales responsiveness.

Sales and Marketing. Sales and marketing teams can employ our applications to drive growth through deeper customer engagement, reduced sales cycle times, and overall improved collaboration between sales, marketing, and other customer-facing functions. We offer applications that help organizations build their online and mobile brand presence, engage their target audiences across multiple communications channels, collaborate on the creation and publication of content, and gain increased control over marketing workflows, activities, and budgets.

Call Center. Customer service and support environments use our applications to enable agents to resolve issues and to engage customers. We offer applications that help improve customer experience and reduce call volume and cycle times through customer self-service tools and Voice of Customer, or VoC, technology that captures customer sentiment in real-time. We also offers tools designed to improve call center agent productivity by providing more direct access to knowledge and to customer sentiment thereby improving both inbound call outcomes and proactive outbound success. Additional solutions help call center leadership to manage agent performance and measure real-time performance relative to call resolution and customer sentiment, improve performance through gamification, and gather agent feedback to keep employee engagement high.

Human Resources and Legal. Human resources, or HR, legal departments, and law firms use our applications to improve collaboration and operational control and streamline routine processes. We offer applications that automate document management and workflow including, contracts, records, and other documentation that require enhanced security and compliance requirements. Other applications support HR-specific workflows including onboarding, employee management, termination, HR support, and time and expense management.

Through a series of acquisitions and integrations, we have built a diverse family of software applications under the Upland brand and in the product solution categories listed above, each of which addresses a specific enterprise work management need. Our revenue has grown from $22.8 million in 2012 to $149.9 million in 2018 (and to $48.5 million for the three months ended March 31, 2019), representing an approximately 558% growth rate between 2012 and 2018. Historically, our revenues have been primarily generated in the United States, however, as a result of acquisitions made over the past three years of companies with more international presence, domestic revenue as a percentage of total revenue has decreased. During the three months ended March 31, 2019, foreign revenue as a percent of total revenue increased to 33% compared to 22% during the year ended December 31, 2018. We expect this trend to continue in 2019 as a result of the acquisitions of Rant & Rave and Adestra during the fourth quarter of 2018, as a majority of each company's operations reside outside the United States.

To support continued growth, we intend to continue to pursue acquisitions within our core enterprise solution suites of complementary technologies and businesses. This will expand our customer base and market access, resulting in increased benefits of scale. Consistent with our growth strategy, we have made a total of 20 acquisitions from February 2012 through March 31, 2019.

The operating platform that we use to transform acquired companies and drive high levels of operating performance is called UplandOne. This platform consists of six key areas:

High-Touch Customer Success Program. Customer success is a continuous journey based on open communication and establishing clear goals towards value realization and maximum customer success. To achieve this, we have institutionalized a set of unique customer commitments and deliverables we call the Upland Customer Success Program that includes onboarding and training, a dedicated customer success representative, upgraded success plans, quarterly virtual user conferences, periodic executive outreach and Net Promoter Score, or NPS, surveys, and an ongoing customer feedback loop.

Quality-Focused R&D. Our approach to R&D is straight-forward: prioritize customer need, leverage a metrics-driven agile approach with visibility and accountability, and deploy the most up-to-date development systems to ensure quality is built into every step of development.

Customer-Driven Innovation. Customer feedback is at the heart of the Upland customer experience. New features are added and prioritized in our product roadmaps, and then fine-tuned, based on direct customer input. Requests from our Premier Success Plan customers are given additional priority weighting for new features and minor issue resolution. Product feedback outlets include customer success account management, quarterly virtual user conferences, annual customer advisory boards, and Upland's online communities.

Expert Professional Services. Through our Professional Services organization, we are committed to delivering the most value from our customers' investment in our products in the shortest possible time. When we engage on a project, we dedicate a team to the planning, configuration, integration, launch, administration and maintenance of the application.

24x7 Global Support. Upland Global Support includes: prioritized issue escalation and resolution; online and phone support, 24/7/365; access to a community to share and discuss best practices, support tips, training materials, and custom reports; a knowledge-base with alerts, service recommendations, and troubleshooting content; unlimited case submissions and real-time case updates; and full support across the globe. For customers that have more urgent support requirements, Upland Premier Success Plans provide enhanced response times and availability for the most severe support requests.

Enterprise Cloud Platform. Our products run on an enterprise-class cloud environment—delivering power, reliability, and flexibility. We utilize Amazon Web Services, or AWS, for all our cloud-based products and move acquired products to AWS in connection with our acquisition integration program. Our cloud technology provides customers with seamless updates and maintenance (without compromising security or scalability), obviating the need for individualized maintenance and updates that accompanies on-premises installed software solutions. Our applications are scalable and can support large deployments while maintaining required performance levels.

Our operating results in a given period can fluctuate based on the mix of subscription and support, perpetual license, and professional services revenue. For the twelve months ended December 31, 2018, 2017 and 2016, our subscription and support revenue accounted for 91%, 87% and 88% of total revenue, respectively. For the three months ended March 31, 2019 and 2018, our subscription and support revenue accounted for 93% and 88%, respectively. Historically, we have sold certain of our applications under perpetual licenses, which also are paid in advance. For the twelve months ended December 31, 2018, 2017 and 2016, our perpetual license revenue accounted for 3%, 4% and 2% of

total revenue, respectively. For the three months ended March 31, 2019 and 2018, our perpetual license revenue accounted for 1% and 5%, respectively. The support agreements related to our perpetual licenses are typically one-year in duration and entitle the customer to support and unspecified upgrades. The revenue related to such support agreements is included as part of our subscription and support revenue. Professional services revenue consists of fees related to implementation, data extraction, integration and configuration, and training on our applications. For the twelve months ended December 31, 2018, 2017 and 2016, our professional services revenue accounted for 6%, 9% and 10% of total revenue, respectively. For the three months ended March 31, 2019 and 2018, our professional services revenue accounted for 6% and 7%, respectively.

We were incorporated in Delaware in 2010. Our principal executive offices are located at 401 Congress Avenue, Suite 1850, Austin, TX 78701, and our telephone number is (512) 960-1010.

The Offering


Common stock offered by us		3,300,000 shares of common stock.
Common stock to be outstanding after this offering		24,785,449 shares of common stock (25,280,449 shares of common stock if the underwriters exercise the option discussed below in full).
Option to purchase additional shares		We have granted the underwriters an option to purchase up to an additional 495,000 shares at the public offering price less the underwriting discounts and commissions, which option may be exercised at any time in whole, or from time to time in part, on or before the 30th day following the date of this prospectus supplement.
Use of proceeds		We intend to use the net proceeds from this offering to continue our acquisition strategy and for general corporate purposes. Please read "Use of Proceeds."
NASDAQ Global Market symbol		"UPLD."
Risk factors		See "Risk factors" beginning on page S-9 and in the documents incorporated by reference into this prospectus supplement and accompanying prospectus for a discussion of some of the factors you should carefully consider before deciding to invest in shares of our common stock.
Voting rights		Each holder of our common stock is entitled to one vote per share on all matters to be voted on by stockholders.

The number of shares of common stock that will be outstanding after this offering is based on 21,485,449 shares of common stock outstanding at May 3, 2019, does not include any securities convertible into or exercisable for common stock.

Summary Historical Consolidated Financial Information

The following table sets forth our summary historical consolidated financial information for the periods indicated. We have derived the summary financial information for each of the years ended December 31, 2016 through December 31, 2018 from our audited consolidated financial statements. The audited consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2018 (the "Annual Report") are incorporated by reference herein. This summary financial information should be read in conjunction with the section entitled "Management's Discussion and Analysis of Financial Condition and Results of Operations" and the consolidated financial statements and related notes thereto contained in our Annual Report, which is incorporated herein by reference. See "Where you can find more information" and "Incorporation by reference."

	Year Ended December 31,

	2018			2017			2016
	(dollars in thousands, except share and per share data)
Revenue:
Subscription and support	$	136,578		$	85,467		$	65,552
Perpetual license		3,902			4,346			1,650

Total product revenue		140,480			89,813			67,202
Professional services		9,405			8,139			7,565

Total revenue		149,885			97,952			74,767
Cost of revenue:
Subscription and support		42,881			28,454			22,734
Professional services		5,708			5,193			4,831

Total cost of revenue		48,589			33,647			27,565
Gross profit		101,296			64,305			47,202
Operating expenses:
Sales and marketing		20,935			15,307			12,160
Research and development		21,320			15,795			14,919
Refundable Canadian tax credits		(406	)		(542	)		(513	)
General and administrative		32,041			23,291			18,286
Depreciation and amortization		14,272			6,498			5,291
Acquisition-related expenses		18,728			15,092			5,583

Total operating expenses		106,890			75,441			55,726

Loss from operations		(5,594	)		(11,136	)		(8,524	)
Other expense:
Interest expense, net		(13,273	)		(6,582	)		(2,781	)
Other income (expense), net		(1,781	)		289			(678	)

Total other expense		(15,054	)		(6,293	)		(3,459	)

Loss before provision for income taxes		(20,648	)		(17,429	)		(11,983	)
Benefit from (provision for) income taxes		9,809			(1,296	)		(1,530	)

Net Loss	$	(10,839	)	$	(18,725	)	$	(13,513	)
Net loss per common share:
Net loss per common share, basic and diluted	$	(0.54	)	$	(1.02	)	$	(0.82	)
Weighted-average common shares outstanding, basic and diluted		19,985,528			18,411,247			16,472,799

	December 31,

	2018		2017		2016
	(dollars in thousands)
Consolidated Balance Sheet Data:
Cash and cash equivalents	$	16,738	$	22,326	$	28,758
Property and equipment, net		2,827		2,927		4,356
Intangible assets, net		179,572		70,043		28,512
Goodwill		225,322		154,607		69,097
Total assets		483,198		281,259		150,588
Deferred revenue		58,204		45,377		23,799
Total liabilities		395,891		189,844		91,575
Total stockholders' equity		87,307		91,415		59,013

	Year Ended December 31,

	2018			2017			2016
	(dollars in thousands, except %)
Other Financial Data:
Annualized recurring revenue value at year-end(1)	$	131,919		$	106,099		$	63,968
Annual net dollar retention rate(2)		98	%		93	%		95	%
Adjusted EBITDA(3)	$	53,105		$	30,316		$	12,616

(1): Annualized recurring revenue value at year-end. The value as of December 31 equals the monthly value of our recurring revenue contracts measured as of December 31 multiplied by 12. This measure excludes the revenue value of certain uncontracted overage fees and on-demand service fees. See "Management's Discussion and Analysis of Financial Condition and Results of Operations—Key Metrics" in our Annual Report for additional discussion of this key metric.
(2): Annual net dollar retention rate. We define annual net dollar retention rate as of December 31 as the aggregate annualized recurring revenue value at December 31 from those customers that were also customers as of December 31 of the prior fiscal year, divided by the aggregate annualized recurring revenue value from all customers as of December 31 of the prior fiscal year. See "Management's Discussion and Analysis of Financial Condition and Results of Operations—Key Metrics" in our Annual Report for additional discussion of this key metric.
(3): Adjusted EBITDA. We monitor our Adjusted EBITDA to help us evaluate the effectiveness and efficiency of our operations. Adjusted EBITDA is a non-GAAP financial measure. We define Adjusted EBITDA as net income (loss), calculated in accordance with GAAP, plus net income (loss) from discontinued operations, depreciation and amortization expense, interest expense, net, other expense (income), net, provision for income taxes, stock-based compensation expense, acquisition-related expenses, non-recurring litigation costs, and purchase accounting adjustments for deferred revenue. Prior to the filing of our Annual Report, we did not include purchase accounting adjustments for deferred revenue as a component of Adjusted EBITDA, and as such, the prior year Adjusted EBITDA amounts presented herein have been recast to reflect the inclusion of purchase accounting adjustments for deferred revenue.

The following table presents a reconciliation of net loss to Adjusted EBITDA:

	Year Ended December 31,

	2018			2017			2016
	(dollars in thousands)
Net Loss	$	(10,839	)	$	(18,725	)	$	(13,513	)
Depreciation and amortization expense		21,347			11,914			9,794
Interest expense, net		13,273			6,582			2,781
Other expense (income), net		1,781			(289	)		678
Provision for (benefit from) income taxes		(9,809	)		1,296			1,530
Stock-based compensation expense		14,130			9,977			4,333
Acquisition-related expense		18,728			15,092			5,583
Nonrecurring litigation expense		—			—			25
Purchase accounting deferred revenue discount		4,494			4,469			1,405

Adjusted EBITDA	$	53,105		$	30,316		$	12,616

We believe that Adjusted EBITDA provides useful information to management, investors and others in understanding and evaluating our operating results for the following reasons:

•: Adjusted EBITDA is widely used by investors and securities analysts to measure a company's operating performance without regard to items that can vary substantially from company to company depending upon their financing, capital structures and the method by which assets were acquired;
•: Our management uses Adjusted EBITDA in conjunction with GAAP financial measures for planning purposes, in the preparation of our annual operating budget, as a measure of our operating performance, to assess the effectiveness of our business strategies and to communicate with our board of directors concerning our financial performance because Adjusted EBITDA eliminates the impact of items that we do not consider indicative of our core operating performance; and
•: Adjusted EBITDA provides more consistency and comparability with our past financial performance, facilitates period-to-period comparisons of our operations and also facilitates comparisons with other companies, many of which use similar non-GAAP financial measures to supplement their GAAP results.

Adjusted EBITDA should not be considered as an alternative to net loss or any other measure of financial performance calculated and presented in accordance with GAAP. The use of Adjusted EBITDA as an analytical tool has limitations such as:

•: depreciation and amortization are non-cash charges, and the assets being depreciated or amortized will often have to be replaced in the future and Adjusted EBITDA does not reflect cash requirements for such replacements; however, much of the depreciation and amortization currently reflected relates to amortization of acquired intangible assets as a result of business combination purchase accounting adjustments, which will not need to be replaced in the future;
•: Adjusted EBITDA may not reflect changes in, or cash requirements for, our working capital needs or contractual commitments;
•: Adjusted EBITDA does not reflect the potentially dilutive impact of stock-based compensation;
•: Adjusted EBITDA does not reflect interest or tax payments that could reduce cash available for use; and
•: other companies, including companies in our industry, might calculate Adjusted EBITDA or similarly titled measures differently, which reduces their usefulness as comparative measures.

Because of these limitations, you should consider Adjusted EBITDA together with other financial performance measures, including various cash flow metrics, net loss and our other GAAP results.

An investment in our common stock involves a significant degree of risk. You should carefully consider the following risk factors regarding the common stock and this offering, as well as the risk factors incorporated by reference in this prospectus supplement from our Annual Report and any subsequent Quarterly Report on Form 10-Q under the heading "Risk Factors", together with all of the other information included or incorporated by reference in this prospectus supplement and the accompanying prospectus, before you decide whether to purchase shares. The risks and uncertainties described below and in such incorporated documents are not the only risks and uncertainties that we face. Additional risks and uncertainties not currently known to us or that we currently deem immaterial also may impair our financial condition and business operations. If any of the following risks actually occurs, our business's financial condition and operating results would suffer. The risks discussed below also include forward-looking statements and our actual results may differ substantially from those discussed in those forward-looking statements. See "Forward-Looking Statements."

The market price of our common stock may be volatile, which could result in substantial losses for investors.

The market price of our common stock could be subject to significant fluctuations. Some of the factors that may cause the market price of our common stock to fluctuate include:

In the past, following periods of volatility in the market price of a company's securities, securities class action litigation has often been brought against that company. Because of the potential volatility of our stock price, we may become the target of securities litigation in the future. If we were to become involved in securities litigation, it could result in substantial costs, divert management's attention and resources from our business and adversely affect our business.

If securities or industry analysts do not publish, or cease publishing, research or reports about us, our business or our market, if they publish negative evaluations of our stock, or if we fail to meet the expectations of analysts, the price of our stock and trading volume could decline.

The trading market for our common stock will be influenced by the research and reports that industry or securities analysts may publish about us, our business, our market or our competitors. If few analysts commence coverage of us, the trading price of our stock would likely decrease if one or more of the analysts covering our business downgrade their evaluation of our stock, the price of our stock could decline. If one or more of these analysts cease to cover our stock, we could lose visibility in the market for our stock, which in turn could cause our stock price to decline. Furthermore, if our operating results fail to meet analysts' expectations our stock price would likely decline.

Sales of a substantial number of shares of our common stock in the public market by our existing stockholders could cause our stock price to fall.

The price of our common stock could decline if there are substantial sales of our common stock in the public stock market. If we sell a significant amount of stock at one time, our stock price could be negatively impacted by such sale. We also have registered shares of common stock that we may issue under our stock-based compensation plans, which can be freely sold in the public market upon issuance. Our 2014 Equity Incentive Plan provides for automatic increases to the number of shares available for issuance thereunder and we undertake each year to add those shares to a registration statement on Form S-8. These increases could have a negative effect on our stock price as the holders of such shares elect to sell their shares.

Our existing directors, executive officers and principal stockholders have substantial control over us, which could limit your ability to influence the outcome of key transactions, including a change of control.

As of May 3, 2019, our directors, executive officers, principal stockholders and their affiliates beneficially owned or controlled, directly or indirectly, a majority of our outstanding common stock. As a result, these stockholders, acting together, could have significant influence over the outcome of matters submitted to our stockholders for approval, including the election or removal of directors, any amendments to our certificate of incorporation or bylaws and any merger, consolidation or sale of all or substantially all of our assets, and over the management and affairs of our company. This concentration of ownership may also have the effect of delaying or preventing a change in control of our company or discouraging others from making tender offers for our shares and might affect the market price of our common stock.

Because we do not expect to pay any dividends on our common stock for the foreseeable future, our investors may never receive a return on their investment.

We do not anticipate that we will pay any cash dividends to holders of our common stock in the foreseeable future. Instead, we plan to retain any earnings to maintain and expand our existing operations. In addition, our ability to pay cash dividends is currently limited by the terms of our existing loan facility, which prohibits our payment of dividends on our capital stock without prior consent, and any future credit facility may contain terms prohibiting or limiting the amount of dividends that may be declared or paid on our common stock. Accordingly, investors must rely on sales

of their common stock after price appreciation, which may never occur, as the only way to realize any return on their investment.

Anti-takeover provisions in our amended and restated certificate of incorporation and our amended and restated bylaws, as well as provisions of Delaware law, might discourage, delay or prevent a change in control of our company or changes in our board of directors or management and, therefore, depress the trading price of our common stock.

Provisions in our certificate of incorporation and bylaws, as amended and restated, will contain provisions that may depress the market price of our common stock by acting to discourage, delay or prevent a merger, acquisition or other change in control that stockholders may consider favorable, including transactions in which you might otherwise receive a premium for your shares of our common stock. These provisions may also prevent or frustrate attempts by our stockholders to replace or remove members of our board of directors or our management. These provisions include the following:

As a Delaware corporation, we are also subject to provisions of Delaware law, including Section 203 of the Delaware General Corporation Law, which limits the ability of stockholders owning in excess of 15% of our outstanding voting stock from engaging in certain business combinations with us.

Any provision of our certificate of incorporation and bylaws or Delaware law that has the effect of delaying or deterring a change in control could limit the opportunity for our stockholders to receive a premium for their shares of our common stock and could also affect the price that some investors are willing to pay for our common stock. The existence of the foregoing provisions and anti-takeover

measures could limit the price that investors might be willing to pay in the future for shares of our common stock. They could also deter potential acquirers of our company, thereby reducing the likelihood that you could receive a premium for your common stock in an acquisition.

Our management might apply the proceeds of this offering in ways that do not increase the value of your investment.

Our management will have broad discretion as to the use of the net proceeds of this offering and you will be relying on the judgment of our management regarding the application of these proceeds. We might apply the net proceeds of this offering in ways with which you do not agree, or in ways that do not yield a favorable return. If our management applies these proceeds in a manner that does not yield a significant return, if any, on our investment of these net proceeds, it would adversely affect the market price of our common stock. For more information on our management's planned use of proceeds, please read "Use of Proceeds" elsewhere in this prospectus supplement and the accompanying prospectus. Pending their use, we may also invest the net proceeds from this offering in a manner that does not produce income or that loses value.

It is likely that our ability to use our U.S. net operating loss carryforwards and certain other tax attributes will be limited as a result of this offering.

As of December 31, 2018, we had federal net operating loss carryforwards of approximately $204.8 million and research and development credit carryforwards of approximately $3.5 million, which begin expiring in 2019. Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, or the Code, if a corporation undergoes an "ownership change," the corporation's ability to use its pre-change net operating loss carryforwards and other pre-change tax attributes, such as research tax credits, to offset its post-change income and taxes may be limited. In general, an "ownership change" occurs if there is a cumulative change in our ownership by "5% shareholders" that exceeds 50 percentage points over a rolling three-year period. Similar rules apply under state tax laws. Based on analysis of acquired net operating losses and credits, utilization of our net operating losses and research and development credits will be subject to annual limitations. The annual limitation will result in the expiration of $82.6 million of federal net operating losses and $3.5 million of research and development credit carryforwards before utilization. In the event that it is determined that we have in the past experienced additional ownership changes, or if we experience one or more ownership changes as a result of this offering or future transactions in our stock, then we may be further limited in our ability to use our net operating loss carryforwards and other tax assets to reduce taxes owed on the net taxable income that we earn. Any such limitations on the ability to use our net operating loss carryforwards and other tax assets could adversely impact our business, financial condition, and operating results.

We estimate that the net proceeds from this offering to us will be approximately $131,670,000.00 (or $151,420,500.00 if the underwriters exercise their option to purchase additional shares in full), after deducting the underwriting discounts and other estimated expenses of this offering payable by us. We intend to use the net proceeds from this offering to continue our acquisition strategy and for general corporate purposes. Consistent with our growth strategy, we evaluate opportunities to acquire additional solutions and technologies on an ongoing basis. As of the date of this prospectus, we have not entered into any agreement to acquire any business that has not been previously disclosed.

If you purchase our common stock in this offering, your interest will be immediately diluted to the extent of the difference between the public offering price per share and the net tangible book value per share of our common stock immediately after this offering.

Our net tangible book value (deficit) at March 31, 2019 was approximately $(315.1) million, or $(14.70) per share, based on 21,443,226 shares of our common stock outstanding as of that date. Net tangible book value per share is calculated by subtracting our total liabilities from our total tangible assets, which is total assets less intangible assets (including goodwill), and dividing this amount by the number of shares of our common stock outstanding.

After giving effect to the sale of 3,300,000 shares of common stock by us the public offering price of $42.00 per share, and after deducting the underwriting discounts and commissions and estimated offering expenses payable by us, our as adjusted net tangible book value (deficit) as of March 31, 2019 would have been $(183.3) million, or $(7.43) per share. This represents an immediate increase in the net tangible book value of $7.27 per share to existing stockholders and immediate dilution of $49.43 per share to investors in this offering, as illustrated by the following table:

If the underwriter exercises in full its option to purchase 495,000 of additional shares from us at the public offering price of $42.00 per share, the as adjusted net tangible book value per share after this offering would be $(6.50) per share, the increase in as adjusted net tangible book value (deficit) per share to existing stockholders would be $8.20 per share and the dilution to new investors purchasing shares in this offering would be $48.50 per share.

For purposes of the above calculation, the number of shares of common stock to be outstanding after this offering is based on 21,443,226 shares outstanding on March 31, 2019.

MATERIAL UNITED STATES FEDERAL INCOME AND ESTATE TAX CONSIDERATIONS FOR NON-U.S. HOLDERS

The following is a summary of the material U.S. federal income and estate tax consideration of the purchase, ownership and disposition of our common stock by a non-U.S. holder (as defined below) that purchases shares issued pursuant to this offering and holds our common stock as a capital asset (generally, property held for investment), but does not purport to be a complete analysis of all the potential tax considerations relating thereto. This summary does not discuss all of the aspects of U.S. federal income and estate taxation that may be relevant to a non-U.S. holder in light of the non-U.S. holder's particular investment or other circumstances. Accordingly, all prospective non-U.S. holders should consult their tax advisors with respect to the U.S. federal, state, local and non-U.S. tax consequences of the purchase, ownership and disposition of our common stock.

This summary is based on provisions of the U.S. Internal Revenue Code of 1986, as amended (which we refer to as the "Code"), applicable U.S. Treasury regulations and administrative and judicial interpretations, all as in effect or in existence on the date of this prospectus. Subsequent developments in U.S. federal income or estate tax law, including changes in law or differing interpretations, which may be applied retroactively, could alter the U.S. federal income tax consequences of the purchase, ownership and disposition of our common stock as described in this summary. We have not sought any ruling from the U.S. Internal Revenue Service, or the IRS, with respect to the statements made and the conclusions reached in the following summary, and there can be no assurance that the IRS will agree with such statements and conclusions.

As used in this summary, the term "non-U.S. holder" means a beneficial owner of our common stock that is not, for U.S. federal income tax purposes:

This discussion does not address all aspects of U.S. federal income taxation that may be relevant to a particular non-U.S. holder in light of that non-U.S. holder's individual circumstances, nor does it address any generation-skipping or gift tax consequences, or any aspects of U.S. state, local or non-U.S. taxes or the applicability of any particular tax treaty. This summary also does not consider any specific facts or circumstances that may apply to a non-U.S. holder and does not address any special tax rules that may apply to particular non-U.S. holders, such as:

In addition, this discussion does not address the tax treatment of partnerships (or entities or arrangements that are treated as partnerships for U.S. federal income tax purposes) or partners in such partnerships. If an entity or arrangement treated as a partnership for U.S. federal income tax purposes holds our common stock, the U.S. federal income tax treatment of a partner of the partnership may depend upon the status of the partner and the activities of the partnership. Such partnerships and partners should consult their tax advisors as to the particular U.S. federal income tax consequences of the purchase, ownership and disposition of our common stock that are applicable to them.

You are urged to consult your tax advisor with respect to the application of the U.S. federal income and estate tax laws to your particular situation, as well as any tax consequences of the purchase, ownership and disposition of our common stock arising under the U.S. federal generation-skipping or gift tax rules or under the laws of any State of the United States or any local, non-U.S. or other taxing jurisdiction, or under any applicable tax treaty.

As discussed above, we do not anticipate that we will pay any cash dividends to holders of our common stock in the foreseeable future. In the event that we do make a distribution of cash or property with respect to our common stock, such distributions generally will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a return of your investment and will first reduce your adjusted tax basis in our common stock (determined separately with respect to each share of our common stock), but not below zero, and then any remaining excess will be treated as gain from the sale of that stock, subject to the tax treatment described below in "Sale or Other Taxable Disposition." Any such distribution will also be subject to the discussion below under the heading "FATCA."

The gross amounts of cash distributions on our common stock paid to you that are treated as dividends generally will be subject to withholding of U.S. federal income tax at a rate of 30%, or a lower rate under an applicable income tax treaty. We may withhold up to 30% of either (i) the gross amount of the entire distribution, even if the amount of the distribution is greater than the amount constituting a dividend, as described above or (ii) the amount of the distribution we project will be a dividend, based upon a reasonable estimate of both our current and our accumulated earnings and profits for the taxable year in which the distribution is made.

To claim the benefit of an applicable income tax treaty, you will be required to provide to the applicable withholding agent a properly executed IRS Form W-8BEN, IRS Form W-8BEN-E (or other applicable or successor form) in accordance with applicable certification and disclosure requirements. These forms may be required to be periodically updated. If you are eligible for a reduced rate of withholding of U.S. federal income tax under an income tax treaty, you may obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim for a refund with the IRS. You should consult your tax advisor regarding your potential entitlement to benefits under a relevant income tax treaty and the manner of claiming the benefits.

Notwithstanding the above, dividends paid on our common stock that are effectively connected with your conduct of a trade or business in the United States and, if required by an applicable income tax treaty, are attributable to a permanent establishment or fixed base maintained by you in the United States, will be taxed on a net income basis at the regular graduated rates generally applicable to United States persons. In that case, withholding of U.S. federal income tax discussed above will not apply if you provide to the applicable withholding agent a properly executed IRS Form W-8ECI (or other applicable or successor form) in accordance with applicable certification and disclosure requirements. In addition, if you are treated as a corporation for U.S. federal income tax purposes, you may be subject to a "branch profits tax" at a 30% rate, or a lower rate under an applicable income tax treaty, on your earnings and profits (attributable to dividends on our common stock or otherwise) that are effectively connected with your conduct of a trade or business within the United States, subject to adjustments.

Subject to the discussions of backup withholding and FATCA below, you generally will not be subject to U.S. federal income tax (including withholding thereof) on any gain recognized on a sale or other disposition of our common stock unless:

Generally, a corporation is a USRPHC if the fair market value of its "U.S. real property interests" equals or exceeds 50% of the sum of the fair market value of its worldwide real property interests plus its other assets used or held for use in a trade or business. We believe that we are not currently, and we do not anticipate becoming in the future, a USRPHC. However, because the determination of whether we are a USRPHC depends on the fair market value of our U.S. real property relative to the fair market value of our other business assets, there can be no assurance that we will not become a USRPHC in the future. Even if we become a USRPHC, however, as long as our common stock is regularly traded on an established securities market, such common stock will not be treated as United States real property interests (and hence will not be subject to withholding by reason of us otherwise qualifying as a USRPHC) unless you actually, indirectly or constructively hold more than five percent of our outstanding common stock at any time during the applicable period that is specified in the Code. Non-U.S. holders who intend to acquire more than 5% of our common stock are encouraged to consult their tax advisors with respect to the U.S. tax consequences of a disposition of our common stock.

Non-U.S. Holders should consult their tax advisors regarding any applicable income tax treaties that may provide for different rules or rates.

The applicable withholding agent generally will be required to report to the IRS and to you the amount of any distributions (whether or not they constitute dividends for U.S. federal income tax purposes) paid to you, your name and address, and the amount of U.S. federal income tax, if any, withheld. Copies of the information returns reporting such distributions and any withholding may also be made available to the tax authorities in the country in which you reside under the provisions of a treaty or agreement. Payments of dividends or of proceeds on the disposition of stock made to you may be subject to additional information reporting and backup withholding at a current rate of 24% unless you: establish an exemption, for example by properly certifying your non-U.S. status on an IRS Form W-8BEN, IRS Form W-8BEN-E or another appropriate version of IRS Form W-8, or otherwise satisfy documentary evidence requirements for establishing that you are not a United States person. Notwithstanding the foregoing, backup withholding and information reporting may apply if either we or our paying agent has actual knowledge, or reason to know, that you are a U.S. person.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit, provided the required information is timely furnished to the IRS.

Sections 1471 through 1474 of the Code and related Treasury Regulations, together with other Treasury Department or IRS guidance issued thereunder, and intergovernmental agreements, legislation, rules and other official guidance adopted pursuant to such intergovernmental agreements (commonly referred to as "FATCA") generally imposes a U.S. federal withholding tax of 30% on any dividends paid with respect to our common stock if paid to a "foreign financial institution" or a "non-financial foreign entity" (each as specifically defined for this purpose) (including, in some cases, when such foreign financial institution or non-financial foreign entity is acting as an intermediary), unless (i) in the case of a foreign financial institution, such institution enters into an agreement with the U.S. government to, among other things, withhold on certain payments and to collect and provide to the U.S. tax authorities substantial information regarding U.S. account holders of such institution (which includes certain equity and debt holders of such institution, as well as certain account holders that are foreign entities with U.S. owners); (ii) in the case of a non-financial foreign entity, such entity provides the withholding agent with either a certification (generally on an IRS Form W-8BEN-E) that it does not have any substantial direct or indirect U.S. owners or identifying each direct and indirect U.S. owner of the entity; or (iii) the foreign financial institution or non-financial foreign entity otherwise qualifies for an exemption from these rules and provides appropriate documentation (such as an IRS Form W-8BEN-E). Under certain circumstances, a non-U.S. holder may be eligible for refunds or credits of such taxes.

On December 13, 2018, the IRS and the Treasury Department issued proposed regulations that provide certain guidance and relief from the regulatory burden associated with FATCA (the "Proposed Regulations"). The Proposed Regulations provide that the gross proceeds from a disposition of stock are no longer subject to the 30% federal withholding tax. With limited exceptions, the IRS and the Treasury Department provide that taxpayers can generally rely on the Proposed Regulations until final regulations are issued.

An intergovernmental agreement between the United States and an applicable foreign country may modify the requirements described in this section. You are encouraged to consult with your own tax advisors regarding the possible implications of this legislation on your investment in our common stock.

Prospective investors are encouraged to consult with their own tax advisors regarding the possible application of FATCA to their investment in our common stock.

Shares of our common stock that are owned (or deemed to be owned) by an individual who is not a citizen or resident of the United States (as specially defined for U.S. federal estate tax purposes) at the time of death will be includable in such individual's gross estate for U.S. federal estate tax purposes, unless an applicable estate or other tax treaty provides otherwise, and, therefore, may be subject to U.S. federal estate tax.

The preceding discussion of U.S. federal income and estate tax considerations is for general information only. It is not tax advice. Each prospective investor should consult its tax advisor regarding the particular U.S. federal, state, local and non-U.S. tax consequences of the purchase, ownership and disposition of our common stock, including the consequences of any proposed change in applicable laws.

Under the terms and subject to the conditions contained in an underwriting agreement dated as of the date of this prospectus supplement, we have agreed to sell to the underwriters named below, for whom Credit Suisse Securities (USA) LLC and Jefferies LLC are acting as representatives, the following respective numbers of shares of common stock:

The underwriting agreement provides that the underwriters are obligated to purchase all the shares of common stock in the offering if any are purchased, other than those shares covered by the option described below. The underwriting agreement also provides that if an underwriter defaults, the purchase commitments of non-defaulting underwriters may be increased or the offering may be terminated.

We have granted to the underwriters a 30-day option to purchase up to 495,000 additional shares at the public offering price less the underwriting discounts and commissions.

The underwriters propose to offer the shares of common stock initially at the public offering price on the cover page of this prospectus supplement and to selling group members at that price less a selling concession of $42.00 per share. The underwriters may allow a discount of $2.10 per share on sales to other broker-dealers. After the public offering, the representatives may change the public offering price and concession to broker-dealers.

We estimate that our total expenses for this offering, excluding the underwriting discounts and commissions, will be approximately $300,000, which will be paid by us. We have also agreed to reimburse the underwriters for certain FINRA-related expenses incurred by them in connection with this offering.

The representatives have informed us that the underwriters do not expect sales to accounts over which the underwriters have discretionary authority to exceed 5% of the shares of common stock being offered.

We have agreed that we will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, or file with the Securities and Exchange Commission a registration statement under the

Securities Act relating to, any shares of our common stock or securities convertible into or exchangeable or exercisable for any shares of our common stock, or publicly disclose the intention to make any offer, sale, pledge, disposition or filing, without the prior written consent of Credit Suisse Securities (USA) LLC and Jefferies LLC and for a period of 90 days after the date of this prospectus supplement except for (i) grants of employee stock options or other equity-based awards under our equity incentive plan, (ii) issuances of common stock pursuant to the exercise of such options or other equity-based awards or (iii) issuances of common stock pursuant to the conversion or exchange of convertible or exchangeable securities (including cashless or "net" exercises) or the exercise of options outstanding on the date hereof.

Our officers and directors have agreed that they will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, any shares of our common stock or securities convertible into or exchangeable or exercisable for any shares of our common stock, enter into a transaction that would have the same effect, or enter into any swap, hedge or other arrangement that transfers, in whole or in part, any of the economic consequences of ownership of our common stock, whether any of these transactions are to be settled by delivery of our common stock or other securities, in cash or otherwise, or publicly disclose the intention to make any offer, sale, pledge or disposition, or to enter into any transaction, swap, hedge or other arrangement, without, in each case, the prior written consent of Credit Suisse Securities (USA) LLC and Jefferies LLC for a period of 90 days after the date of this prospectus supplement, subject to limited exceptions.

The restrictions described in the immediately preceding paragraph shall not apply to:

Credit Suisse Securities (USA) LLC and Jefferies LLC, in their sole discretion, may release shares of our common stock, or any security convertible into our common stock, in whole or in part at any time with or without notice.

We have agreed to indemnify the underwriters against liabilities under the Securities Act, or contribute to payments that the underwriters may be required to make in that respect.

In connection with the offering the underwriters may engage in stabilizing transactions, over-allotment transactions, syndicate covering transactions, penalty bids and passive market making in accordance with Regulation M under the Exchange Act.

These stabilizing transactions, syndicate covering transactions and penalty bids may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of the common stock. As a result the price of our common stock may be higher than the price that might otherwise exist in the open market. These transactions may be effected on the NASDAQ Global Market or otherwise and, if commenced, may be discontinued at any time.

A prospectus supplement in electronic format may be made available on the web sites maintained by one or more of the underwriters, or selling group members, if any, participating in this offering and one or more of the underwriters participating in this offering may distribute prospectuses electronically. The representatives may agree to allocate a number of shares to underwriters and selling group members for sale to their online brokerage account holders. Internet distributions will be allocated by the underwriters and selling group members that will make internet distributions on the same basis as other allocations.

Certain of the underwriters and their affiliates have provided in the past to us and our affiliates and may provide from time to time in the future certain commercial banking, financial advisory, investment banking and other services for us and such affiliates in the ordinary course of their business, for which they have received and may continue to receive customary fees and commissions. In addition, from time to time, certain of the underwriters and their affiliates may effect transactions for their own

account or the account of customers, and hold on behalf of themselves or their customers, long or short positions in our debt or equity securities or loans, and may do so in the future.

Other than in the U.S., no action has been taken by us or the underwriters that would permit a public offering of the securities offered by this prospectus supplement in any jurisdiction where action for that purpose is required. The securities offered by this prospectus supplement may not be offered or sold, directly or indirectly, nor may this prospectus supplement or any other offering material or advertisements in connection with the offer and sale of any such securities be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus supplement comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus supplement. This prospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus supplement in any jurisdiction in which such an offer or a solicitation is unlawful.

Each underwriter has represented and agreed that (a) it has only communicated or caused to be communicated and will only communicate or cause to be communicated an invitation or inducement to engage in investment activity (within the meaning of Section 21 of the Financial Services and Markets Act 2000 (the "FSMA")) received by it in connection with the issue or sale of the shares in circumstances in which Section 21(1) of the FSMA does not apply to us; and (b) it has complied and will comply with all applicable provisions of the FSMA with respect to anything done by it in relation to the shares in, from or otherwise involving the United Kingdom.

In relation to each Member State of the European Economic Area (each, a "Relevant Member State") an offer to the public of any shares which are the subject of the offering contemplated by this Prospectus (the "Shares") may not be made in that Relevant Member State, except that an offer to the public in that Relevant Member State of any Shares may be made at any time under the following exemptions under the Prospectus Directive:

provided that no such offer of Shares shall result in a requirement for the publication by us or any underwriter of a prospectus pursuant to Article 3 of the Prospectus Directive.

For the purposes of this provision, the expression an "offer to the public" in relation to any Shares in any Relevant Member State means the communication in any form and by any means of sufficient information on the terms of the offer and any Shares to be offered so as to enable an investor to decide to purchase any Shares, as the same may be varied in that Member State by any measure implementing the Prospectus Directive in that Member State, the expression "Prospectus Directive" means Directive 2003/71/EC as amended, including by Directive 2010/73/EU, the 2010 PD Amending Directive, and includes any relevant implementing measure in the Relevant Member State.

The securities have not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than (a) to "professional investors" as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong and any rules made under that Ordinance; or (b) in other circumstances which do not result in the document being a "prospectus" as defined in the Companies Ordinance (Cap. 32) of Hong Kong or which do not constitute an offer to the public within the meaning of that Ordinance. No advertisement, invitation or document relating to the securities has been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to securities which are or are intended to be disposed of only to persons outside Hong Kong or only to "professional investors" as defined in the Securities and Futures Ordinance and any rules made under that Ordinance.

This prospectus has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of Non-CIS Securities may not be circulated or distributed, nor may the Non-CIS Securities be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the "SFA"), (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to Section 275(1A), and in accordance with the conditions specified in Section 275, of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

Where the Non-CIS Securities are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

securities (as defined in Section 239(1) of the SFA) of that corporation or the beneficiaries' rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the Non-CIS Securities pursuant to an offer made under Section 275 of the SFA except:

This document is not intended to constitute an offer or solicitation to purchase or invest in the shares described herein. The shares may not be publicly offered, sold or advertised, directly or indirectly, in, into or from Switzerland and will not be listed on the SIX Swiss Exchange or on any other exchange or regulated trading facility in Switzerland. Neither this document nor any other offering or marketing material relating to the shares constitutes a prospectus as such term is understood pursuant to article 652a or article 1156 of the Swiss Code of Obligations or a listing prospectus within the meaning of the listing rules of the SIX Swiss Exchange or any other regulated trading facility in Switzerland, and neither this document nor any other offering or marketing material relating to the shares may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this document nor any other offering or marketing material relating to the offering, nor Upland nor the shares have been or will be filed with or approved by any Swiss regulatory authority. The shares are not subject to the supervision by any Swiss regulatory authority, e.g., the Swiss Financial Markets Supervisory Authority (FINMA), and investors in the shares will not benefit from protection or supervision by such authority.

The distribution of the shares of common stock in Canada is being made only in the provinces of Ontario, Quebec, Alberta and British Columbia on a private placement basis exempt from the requirement that we prepare and file a prospectus with the securities regulatory authorities in each province where trades of these securities are made. Any resale of the shares of common stock in Canada must be made under applicable securities laws which may vary depending on the relevant jurisdiction, and which may require resales to be made under available statutory exemptions or under a discretionary exemption granted by the applicable Canadian securities regulatory authority. Purchasers are advised to seek legal advice prior to any resale of the securities.

By purchasing shares of common stock in Canada and accepting delivery of a purchase confirmation, a purchaser is representing to us and the dealer from whom the purchase confirmation is received that:

Canadian purchasers are hereby notified that the underwriters are relying on the exemption set out in section 3A.3 or 3A.4, if applicable, of National Instrument 33-105—Underwriting Conflicts from having to provide certain conflict of interest disclosure in this document.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if the offering memorandum (including any amendment thereto) such as this document contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser's province or territory. The purchaser of these securities in Canada should refer to any applicable provisions of the securities legislation of the purchaser's province or territory for particulars of these rights or consult with a legal advisor.

All of our directors and officers as well as the experts named herein may be located outside of Canada and, as a result, it may not be possible for Canadian purchasers to effect service of process within Canada upon us or those persons. All or a substantial portion of our assets and the assets of those persons may be located outside of Canada and, as a result, it may not be possible to satisfy a judgment against us or those persons in Canada or to enforce a judgment obtained in Canadian courts against us or those persons outside of Canada.

Canadian purchasers of shares of common stock should consult their own legal and tax advisors with respect to the tax consequences of an investment in the shares of common stock in their particular circumstances and about the eligibility of the shares of common stock for investment by the purchaser under relevant Canadian legislation.

This prospectus supplement relates to an Exempt Offer in accordance with the Offered Securities Rules of the Dubai Financial Services Authority ("DFSA"). This prospectus supplement is intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement nor taken steps to verify the information set forth herein and has no responsibility for the prospectus supplement. The securities to which this prospectus supplement relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the securities offered should conduct their own due diligence on the securities. If you do not understand the contents of this prospectus supplement you should consult an authorized financial advisor.

No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission, or ASIC, in relation to the offering. This prospectus supplement does not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001, or the Corporations Act, and does not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.

Any offer in Australia of the shares may only be made to persons, or the Exempt Investors, who are "sophisticated investors" (within the meaning of section 708(8) of the Corporations Act), "professional investors" (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act so that it is lawful to offer the shares without disclosure to investors under Chapter 6D of the Corporations Act.

The shares applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under the offering, except in circumstances where disclosure to investors under Chapter 6D of the Corporations Act would not be required pursuant to an exemption under section 708 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapter 6D of the Corporations Act. Any person acquiring shares must observe such Australian on-sale restrictions.

This prospectus supplement contains general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus supplement is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

The shares have not been and will not be registered under the Financial Instruments and Exchange Law of Japan (Law No. 25 of 1948, as amended) and, accordingly, will not be offered or sold, directly or indirectly, in Japan, or for the benefit of any Japanese Person or to others for re-offering or resale, directly or indirectly, in Japan or to any Japanese Person, except in compliance with all applicable laws, regulations and ministerial guidelines promulgated by relevant Japanese governmental or regulatory authorities in effect at the relevant time. For the purposes of this paragraph, "Japanese Person" shall mean any person resident in Japan, including any corporation or other entity organized under the laws of Japan.

The transfer agent and registrar for our common stock is Broadridge Corporate Issuer Solutions, Inc.

Certain legal matters will be passed upon for us by Pillsbury Winthrop Shaw Pittman LLP, counsel to us. Certain legal matters will be passed upon for the underwriters by DLA Piper LLP (US), Austin, Texas, counsel to the Underwriters.

The consolidated financial statements of Upland Software, Inc. appearing in Upland Software, Inc.'s Annual Report (Form 10-K) for the year ended December 31, 2018, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy any document that we have filed at the SEC's Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the operation of the Public Reference Room. The SEC maintains an Internet site that contains reports, proxy and information statements and other information regarding issuers that file electronically with the SEC. Our filings are available to the public at the SEC's website at www.sec.gov. In addition, we maintain a website that contains information about us at www.uplandsoftware.com. The information found on, or otherwise accessible through, our website is not incorporated into, and does not form a part of, this prospectus supplement or any other report or document we file with or furnish to the SEC.

We are incorporating the following documents into this prospectus supplement by reference, which means that we are disclosing important information to you by referring to documents that contain the information. The information incorporated by reference is an important part of this prospectus supplement, and information we file later with the SEC will automatically update and supersede the information in this prospectus supplement until all of the shares of common stock offered under this prospectus supplement are sold. We are not, however, incorporating by reference any documents or portions thereof, whether specifically listed below or filed in the future, that are not deemed "filed" with the SEC. We incorporate by reference the documents listed below:

Any statement contained in a document incorporated or deemed to be incorporated by reference in this prospectus supplement will be deemed to be modified or superseded for purposes of this prospectus supplement to the extent that a statement contained in this prospectus supplement or any other subsequently filed document that is deemed to be incorporated by reference herein modifies or supersedes the statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement.

You may request a copy of any or all of the documents incorporated by reference in this prospectus supplement, at no cost, by writing or calling our offices at the following address: Investor Relations, Upland Software, Inc., 401 Congress Avenue, Suite 1850, Austin, Texas 78701, telephone (512) 960-1031. We will not, however, send exhibits to those documents, unless the exhibits are specifically incorporated by reference in those documents.

We may, from time to time, offer and sell the securities identified above in one or more offerings. The aggregate initial offering price of all securities sold under this prospectus will not exceed $250,000,000.

This prospectus describes the general terms of these securities and the general manner in which these securities will be offered. We will provide the specific terms of these securities in supplements to this prospectus. The prospectus supplements will also describe the manner in which these securities will be offered and may also add to, update or change information contained in this prospectus. You should read carefully this prospectus and the accompanying prospectus supplement before you invest.

We may offer and sell these securities separately or together in any combination for sale directly to investors or through underwriters, dealers or agents. If any underwriters, dealers or agents are involved in the sale of any of these securities, we will set forth their names and describe their compensation in the applicable prospectus supplement.

Our common stock is listed on The NASDAQ Global Market under the symbol "UPLD." On , 2018 the last reported sale price of our common stock on The NASDAQ Global Market was $ per share.

Investing in our securities involves risks. See the section entitled "Risk Factors" included in or incorporated by reference into the accompanying prospectus supplement and in the documents we incorporate by reference in this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

We have not authorized anyone to provide any information other than that contained or incorporated by reference in this prospectus, any applicable prospectus supplement or any free writing prospectus prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information in this prospectus and any prospectus supplement, or incorporated by reference, is accurate only as of the dates of those documents. Our business, financial condition, results of operations and prospects may have changed since those dates.

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or SEC, using a "shelf" registration, or continuous offering, process. Under this shelf registration process, we may, from time to time, offer and sell separately or together in any combination the securities described in this prospectus in one or more offerings up to a maximum aggregate offering price of $250,000,000.

This prospectus provides you with a general description of the securities we may offer. Each time we sell securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering and the offered securities. Any prospectus supplement may also add, update or change information contained in this prospectus. Any statement that we make in this prospectus will be modified or superseded by any inconsistent statement made by us in a prospectus supplement. The registration statement we filed with the SEC includes exhibits that provide more detail of the matters discussed in this prospectus. You should read this prospectus and the related exhibits filed with the SEC and any prospectus supplement, together with additional information described under the heading "Where You Can Find More Information," before making your investment decision.

Unless the context otherwise requires, references in this prospectus to "Upland," "we," "us" and "our" refer to Upland Software, Inc.

Investing in our securities involves risk. The prospectus supplement relating to a particular offering will contain or incorporate by reference a discussion of risks applicable to an investment in the securities offered. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed under the heading "Risk Factors" included in or incorporated by reference into the applicable prospectus supplement together with all of the other information contained in the prospectus supplement or appearing in or incorporated by reference into this prospectus, including the risk factors incorporated by reference to our most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q or Current Reports on Form 8-K. The occurrence of any of these risks might cause you to lose all or part of your investment in the offered securities.

We provide cloud-based enterprise work management software. We define enterprise work management software as software applications that enable organizations to plan, manage and execute projects and work. Our family of applications enables users to manage their projects, professional workforce and IT investments, automate document-intensive business processes, and effectively engage with their customers, prospects, and community via the web and mobile technologies.

The continued growth of an information-based economy has given rise to a large and growing group of knowledge workers who operate in dynamic work environments as part of geographically dispersed and virtual teams. We believe that manual processes and legacy on- premise enterprise systems are insufficient to address the needs of the modern work environment. In order for knowledge workers to be successful, they need to interact with intuitive enterprise work systems in a collaborative way, including real-time access. Today, legacy processes and systems are being disrupted and replaced by cloud-based enterprise work management software that improves visibility, collaboration and productivity.

In response to these changes, we are providing organizations and their knowledge workers with software applications that better align resources with business objectives and increase visibility, governance, collaboration, quality of customer experience, and responsiveness to changes in the

business environment. This results in increased work capacity, higher productivity, better execution, and greater levels of customer engagement. Our applications are easy-to-use, scalable, and offer real-time collaboration for knowledge workers distributed on a local or global scale. Our applications address enterprise work challenges in the following categories:

Our subscription agreements are typically sold either on a per-seat basis or on a minimum contracted volume basis with overage fees billed in arrears, depending on the application being sold. We service customers ranging from large global corporations and government agencies to small- and medium-sized businesses. We have customers and end users across a broad range of industries, including financial services, retail, technology, manufacturing, legal, education, consumer goods, media, telecommunications, government, non-profit, food and beverage, healthcare and life sciences.

Through a series of acquisitions and integrations, we have established a diverse family of software applications under the Upland brand and in three product categories (Project & IT Management, Workflow Automation, and Digital Engagement), each of which addresses a specific enterprise work management need.

To support continued growth, we intend to pursue acquisitions of complementary technologies, products and businesses. This will expand our product families, customer base, and market access resulting in increased benefits of scale. We will prioritize acquisitions within our current core product categories including Project & IT Management, Workflow Automation, and Digital Engagement. Consistent with our growth strategy.

We completed our initial public offering in November 2014 and our common stock is listed on the Nasdaq Global Market under the symbol "UPLD."

We were incorporated in Delaware in 2010. Our principal executive offices are located at 401 Congress Avenue, Suite 1850, Austin, TX 78701, and our telephone number is (855) 944-7526.

When used in this prospectus, the words "expects," "believes," "anticipates," "estimates," "may," "could," "intends," and similar expressions are intended to identify forward-looking statements. These statements are subject to known and unknown risks and uncertainties that could cause actual results to differ materially from those projected or otherwise implied by the forward-looking statements. These forward-looking statements speak only as of the date of this prospectus. Given these risks and uncertainties, you should not place undue reliance on these forward-looking statements. We will discuss many of these risks and uncertainties in greater detail in any prospectus supplement under the heading "Risk Factors." Additional cautionary statements or discussions of risks and uncertainties that could affect our results or the achievement of the expectations described in forward-looking statements may also be contained in the documents we incorporate by reference into this prospectus.

These forward-looking statements speak only as of the date of this prospectus. We expressly disclaim any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained herein to reflect any change in our expectations with regard thereto or any change in events, conditions or circumstances on which any such statement is based. You should, however, review additional disclosures we make in our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K filed with the SEC.

Unless we state otherwise in the applicable prospectus supplement, we intend to use the net proceeds from the sale of the securities offered by this prospectus for general corporate purposes. General corporate purposes may include additions to working capital, financing of capital expenditures, repayment or redemption of existing indebtedness, repurchases of stock, and future acquisitions and strategic investment opportunities. Unless we state otherwise in the applicable prospectus supplement, pending the application of net proceeds, we expect to invest the net proceeds in investment grade, interest-bearing securities.

The following is a summary of the general terms of the debt securities. We will file a prospectus supplement that may contain additional terms when we issue debt securities. The terms presented here, together with the terms in a related prospectus supplement, together with any pricing supplement or term sheet, will be a description of the material terms of the debt securities.

We may issue, from time to time, debt securities, in one or more series. These debt securities that we may issue include senior debt securities, senior subordinated debt securities, subordinated debt securities, convertible debt securities and exchangeable debt securities. The debt securities we offer will be issued under an indenture between us and the trustee named in the indenture. The following is a summary of the material provisions of the form of indenture filed as an exhibit to the registration statement of which this prospectus is a part. All capitalized terms have the meanings specified in the indenture. For each series of debt securities, the applicable prospectus supplement for the series may change and supplement the summary below.

As used in this section only, "we," "us" and "our" refer to Upland Software, Inc. excluding our subsidiaries, unless expressly stated or the context otherwise requires.

The indenture does not limit the amount of debt securities that we may issue. It provides that we may issue debt securities for any series of debt securities up to the principal amount that we may authorize. Except for the limitations on consolidation, merger and sale of all or substantially all of our assets contained in the indenture, the terms of the indenture do not contain any covenants or other provisions designed to give holders of any debt securities protection against changes in our operations, financial condition or transactions involving us. For each series of debt securities, any restrictive covenants for those debt securities will be described in the applicable prospectus supplement for those debt securities.

We may issue the debt securities issued under the indenture as "discount securities," which means they may be sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may, for United States federal income tax purposes, be treated as if they were issued with "original issue discount," or OID, because of interest payment and other characteristics. Special United States federal income tax considerations applicable to debt securities issued with original issue discount will be described in more detail in any applicable prospectus supplement.

You should refer to the prospectus supplement relating to a particular series of debt securities for a description of the following terms of the debt securities offered by that prospectus supplement and by this prospectus:

The applicable prospectus supplement will present material United States federal income tax considerations for holders of any debt securities and the securities exchange or quotation system on which any debt securities are to be listed or quoted.

Debt securities may be convertible into or exchangeable for shares of our equity securities or other securities. The terms and conditions of conversion or exchange will be stated in the applicable prospectus supplement. The terms will include, among others, the following:

We cannot consolidate with or merge with or into, or transfer or lease all or substantially all of our assets to, any person, unless we are the surviving corporation or the successor person is a corporation organized under the laws of the United States, any state of the United States or the District of Columbia and expressly assumes our obligations under the debt securities and the indenture. In addition, we cannot complete such a transaction unless immediately after completing the transaction, no event of default under the indenture, and no event that, after notice or lapse of time or both, would become an event of default under the indenture, has occurred and is continuing. When the successor person has assumed our obligations under the debt securities and the indenture, we will be discharged from all our obligations under the debt securities and the indenture except in limited circumstances.

This covenant would not apply to any recapitalization transaction, a change of control affecting us or a highly leveraged transaction, unless the transaction or change of control were structured to include a merger or consolidation or transfer or lease of all or substantially all of our assets.

The indenture provides that the following will be "events of default" with respect to any series of debt securities:

An event of default for a particular series of debt securities does not necessarily constitute an event of default for any other series of debt securities issued under the indenture. For each series of debt securities, any modifications to the above events of default will be described in the applicable prospectus supplement for those debt securities.

The indenture provides that if an event of default specified in the first, second, third, fourth or sixth bullets above occurs and is continuing, either the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series may declare the principal amount of all those debt securities (or, in the case of discount securities or indexed securities, that portion of the principal amount as may be specified in the terms of that series) to be due and payable immediately. If an event of default specified in the fifth bullet above occurs and is continuing, then the principal amount of all those debt securities (or, in the case of discount securities or indexed securities, that portion of the principal amount as may be specified in the terms of that series) will be due and payable immediately, without any declaration or other act on the part of the trustee or any holder. In certain cases, holders of a majority in principal amount of the outstanding debt securities of any series may, on behalf of holders of all those debt securities, rescind and annul a declaration of acceleration.

The indenture imposes limitations on suits brought by holders of debt securities against us. Except for actions for payment of overdue principal or interest, no holder of debt securities of any series may institute any action against us under the indenture unless:

We will be required to file annually with the trustee a certificate, signed by one of our officers, stating whether or not the officer knows of any default by us in the performance, observance or fulfillment of any condition or covenant of the indenture.

We can discharge or decrease our obligations under the indenture as stated below.

We may discharge obligations to holders of any series of debt securities that have not already been delivered to the trustee for cancellation and that have either become due and payable or are by their terms to become due and payable, or are scheduled for redemption, within one year. We may effect a discharge by irrevocably depositing with the trustee cash or government obligations, as trust funds, in an amount certified to be enough to pay when due, whether at maturity, upon redemption or otherwise, the principal of, and any premium and interest on, the debt securities and any mandatory sinking fund payments.

Unless otherwise provided in the applicable prospectus supplement, we may also discharge any and all of our obligations to holders of any series of debt securities at any time, which we refer to as defeasance. We may also be released from the obligations imposed by any covenants of any outstanding series of debt securities and provisions of the indenture, and we may omit to comply with those covenants without creating an event of default under the trust declaration, which we refer to as covenant defeasance. We may effect defeasance and covenant defeasance only if, among other things:

In the case of a defeasance by us, the opinion we deliver must be based on a ruling of the Internal Revenue Service issued, or a change in U.S. federal income tax law occurring, after the date of the indenture, since such a result would not occur under the U.S. federal income tax laws in effect on that date.

Although we may discharge or decrease our obligations under the indenture as described in the two preceding paragraphs, we may not avoid, among other things, our duty to register the transfer or exchange of any series of debt securities, to replace any temporary, mutilated, destroyed, lost or stolen series of debt securities or to maintain an office or agency in respect of any series of debt securities.

The indenture provides that we and the trustee may enter into supplemental indentures without the consent of the holders of debt securities to, among other things:

The indenture also provides that we and the trustee may, with the consent of the holders of not less than a majority in aggregate principal amount of debt securities of each series of debt securities affected by such supplemental indenture then outstanding, add any provisions to, or change in any

manner, eliminate or modify in any way the provisions of, the indenture or any supplemental indenture or modify in any manner the rights of the holders of the debt securities. We and the trustee may not, however, without the consent of the holder of each outstanding debt security affected thereby:

The indenture provides that the holders of not less than a majority in aggregate principal amount of the then outstanding debt securities of any series, by notice to the relevant trustee, may on behalf of the holders of the debt securities of that series waive any default and its consequences under the indenture except:

The indenture provides that there may be more than one trustee under the indenture, each for one or more series of debt securities. If there are different trustees for different series of debt securities, each trustee will be a trustee of a trust under the indenture separate and apart from the trust administered by any other trustee under that indenture. Except as otherwise indicated in this prospectus or any prospectus supplement, any action permitted to be taken by a trustee may be taken by such trustee only on the one or more series of debt securities for which it is the trustee under the indenture. Any trustee under the indenture may resign or be removed from one or more series of debt securities. All payments of principal of, and any premium and interest on, and all registration, transfer, exchange, authentication and delivery of, the debt securities of a series will be effected by the trustee for that series at an office designated by the trustee in New York, New York.

The indenture provides that, except during the continuance of an event of default, the trustee will perform only such duties as are specifically set forth in the indenture. During the existence of an event of default, the trustee will exercise those rights and powers vested in it under the indenture and use the same degree of care and skill in its exercise as a prudent person would exercise under the circumstances in the conduct of such person's own affairs.

If the trustee becomes a creditor of ours, the indenture places limitations on the right of the trustee to obtain payment of claims or to realize on property received in respect of any such claim as security or otherwise. The trustee may engage in other transactions. If it acquires any conflicting

interest relating to any duties concerning the debt securities, however, it must eliminate the conflict or resign as trustee.

No Individual Liability of Incorporators, Stockholders, Officers or Directors

The indenture provides that no past, present or future director, officer, stockholder or employee of ours, any of our affiliates, or any successor corporation, in their capacity as such, shall have any individual liability for any of our obligations, covenants or agreements under the debt securities or the indenture.

The indenture and the debt securities will be governed by, and construed in accordance with, the laws of the State of New York.

This section describes the general terms and provisions of the shares of our common stock, par value of $0.0001 per share, and preferred stock, par value of $0.0001 per share. This description is only a summary. Our restated certificate of incorporation and our bylaws have been filed as exhibits to our periodic reports filed with the SEC, which are incorporated by reference in this prospectus. You should read our restated certificate of incorporation and our bylaws for additional information before you buy any of our common stock, preferred stock or other securities. See "Where You Can Find More Information."

We are authorized to issue 50,000,000 shares of common stock. As of December 5, 2018, there were 21,605,507 shares of common stock issued and outstanding. Each holder of common stock is entitled to one vote for each share of common stock held on all matters submitted to a vote of stockholders. We have not provided for cumulative voting for the election of directors in our restated certificate of incorporation. This means that the holders of a majority of the shares voted can elect all of the directors then standing for election. Subject to preferences that may apply to shares of preferred stock outstanding at the time, the holders of outstanding shares of our common stock are entitled to receive dividends out of assets legally available at the times and in the amounts that our board of directors may determine from time to time. Upon our liquidation, dissolution or winding-up, the holders of common stock are entitled to share ratably in all assets remaining after payment of all liabilities and the liquidation preferences of any outstanding preferred stock. Holders of common stock have no preemptive or conversion rights or other subscription rights. There are no redemption or sinking fund provisions applicable to the common stock. All outstanding shares of common stock are fully paid and nonassessable.

We are authorized to issue 5,000,000 shares of preferred stock. As of November 30, 2018, no shares of preferred stock were issued and outstanding. We may issue preferred stock, in series, with such designations, powers, preferences and other rights and qualifications, limitations or restrictions as our board of directors may authorize, without further action by our stockholders, including:

The particular terms of any series of preferred stock, and the transfer agent and registrar for that series, will be described in a prospectus supplement. Any material United States federal income tax consequences and other special considerations with respect to any preferred stock offered under this prospectus will also be described in the applicable prospectus supplement.

The issuance of preferred stock could decrease the amount of earnings and assets available for distribution to holders of our common stock or adversely affect the rights and powers, including voting rights, of the holders of our common stock. The issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control of our company, which could depress the market price of our common stock.

The provisions of Delaware law, our restated certificate of incorporation and our bylaws described below may have the effect of delaying, deferring or discouraging another party from acquiring control of us.

Delaware Law. We are subject to the provisions of Section 203 of the General Corporation Law of the State of Delaware regulating corporate takeovers. In general, those provisions prohibit a publicly-held Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years following the date that the stockholder became an interested stockholder, unless:

In general, Section 203 defines an interested stockholder as any entity or person beneficially owning 15% or more of the outstanding voting stock of the corporation and any entity or person affiliated with or controlling or controlled by any of these entities or persons.

A Delaware corporation may opt out of these provisions either with an express provision in its original certificate of incorporation or in an amendment to its certificate of incorporation or bylaws approved by its stockholders. However, we have not opted out, and do not currently intend to opt out of, these provisions. The statute could prohibit or delay mergers or other takeover or change in control attempts and, accordingly, may discourage attempts to acquire us.

Charter and Bylaws. Our restated certificate of incorporation and bylaws provide that:

The following description of the depositary shares does not purport to be complete and is subject to and qualified in its entirety by the relevant deposit agreement and the depositary receipts with respect to the depositary shares relating to any particular series of preferred stock. You should read these documents as they, and not this description, will define your rights as a holder of depositary shares. Forms of these documents will be filed with the SEC in connection with the offering of depositary shares.

If we elect to offer fractional interests in shares of preferred stock, we will provide for the issuance by a depositary to the public of receipts for depositary shares. Each depositary share will represent fractional interests of preferred stock. We will deposit the shares of preferred stock underlying the depositary shares under a deposit agreement between us and a bank or trust company selected by us. The bank or trust company must have its principal office in the United States and a combined capital and surplus of at least $50 million. The depositary receipts will evidence the depositary shares issued under the deposit agreement.

The deposit agreement will contain terms applicable to the holders of depositary shares in addition to the terms stated in the depositary receipts. Each owner of depositary shares will be entitled to all the rights and preferences of the preferred stock underlying the depositary shares in proportion to the applicable fractional interest in the underlying shares of preferred stock. The depositary will issue the depositary receipts to individuals purchasing the fractional interests in shares of the related preferred stock according to the terms of the offering described in a prospectus supplement.

The depositary will distribute all cash dividends or other cash distributions received for the preferred stock to the entitled record holders of depositary shares in proportion to the number of depositary shares that the holder owns on the relevant record date. The depositary will distribute only an amount that can be distributed without attributing to any holder of depositary shares a fraction of one cent. The depositary will add the undistributed balance to and treat it as part of the next sum received by the depositary for distribution to holders of depositary shares.

If there is a non-cash distribution, the depositary will distribute property received by it to the entitled record holders of depositary shares, in proportion, insofar as possible, to the number of depositary shares owned by the holders, unless the depositary determines, after consultation with us, that it is not feasible to make such distribution. If this occurs, the depositary may, with our approval, sell such property and distribute the net proceeds from the sale to the holders. The deposit agreement also will contain provisions relating to how any subscription or similar rights that we may offer to holders of the preferred stock will be available to the holders of the depositary shares.

If any series of preferred stock underlying the depositary shares may be converted or exchanged, each record holder of depositary receipts will have the right or obligation to convert or exchange the depositary shares represented by the depositary receipts.

The terms on which the depositary shares relating to the preferred stock of any series may be redeemed, and any amounts distributable upon our liquidation, dissolution or winding up, will be described in the relevant prospectus supplement.

When the depositary receives notice of a meeting at which the holders of the preferred stock are entitled to vote, the depositary will mail the particulars of the meeting to the record holders of the depositary shares. Each record holder of depositary shares on the record date may instruct the depositary on how to vote the shares of preferred stock underlying the holder's depositary shares. The depositary will try, if practical, to vote the number of shares of preferred stock underlying the depositary shares according to the instructions. We will agree to take all reasonable action requested by the depositary to enable it to vote as instructed.

We and the depositary may agree to amend the deposit agreement and the depositary receipt evidencing the depositary shares. Any amendment that (a) imposes or increases certain fees, taxes or other charges payable by the holders of the depositary shares as described in the deposit agreement or that (b) otherwise prejudices any substantial existing right of holders of depositary shares, will not take effect until 30 days after the depositary has mailed notice of the amendment to the record holders of depositary shares. Any holder of depositary shares that continues to hold its shares at the end of the 30-day period will be deemed to have agreed to the amendment.

We may direct the depositary to terminate the deposit agreement by mailing a notice of termination to holders of depositary shares at least 30 days prior to termination. In addition, a deposit agreement will automatically terminate if:

We will pay all fees, charges and expenses of the depositary, including the initial deposit of the preferred stock and any redemption of the preferred stock. Holders of depositary shares will pay transfer and other taxes and governmental charges and any other charges as are stated in the deposit agreement for their accounts.

At any time, the depositary may resign by delivering notice to us, and we may remove the depositary. Resignations or removals will take effect upon the appointment of a successor depositary and its acceptance of the appointment. The successor depositary must be appointed within 60 days after delivery of the notice of resignation or removal and must be a bank or trust company having its principal office in the United States and having a combined capital and surplus of at least $50 million.

The depositary will forward to the holders of depositary shares all reports and communications from us that are delivered to the depositary and that we are required by law, the rules of an applicable securities exchange or our restated certificate of incorporation to furnish to the holders of the preferred stock. Neither we nor the depositary will be liable if the depositary is prevented or delayed by law or any circumstances beyond its control in performing its obligations under the deposit agreement. The deposit agreement limits our obligations and the depositary's obligations to performance in good faith of the duties stated in the deposit agreement. Neither we nor the depositary will be obligated to prosecute or defend any legal proceeding connected with any depositary shares or preferred stock unless the holders of depositary shares requesting us to do so furnish us with satisfactory indemnity. In performing our obligations, we and the depositary may rely upon the written advice of our counsel or accountants, on any information that competent people provide to us and on documents that we believe are genuine.

We may issue warrants for the purchase of debt securities, preferred stock, common stock, depositary shares, or any combination thereof. We may issue warrants independently or together with any other securities offered by any prospectus supplement and may be attached to or separate from the other offered securities. Each series of warrants may be issued under a separate warrant agreement to be entered into by us with a warrant agent. The applicable warrant agent will act solely as our agent in connection with the warrants and will not assume any obligation or relationship of agency or trust for or with any holders or beneficial owners of warrants. Further terms of the warrants and the applicable warrant agreements will be set forth in the applicable prospectus supplement.

The applicable prospectus supplement relating to any particular issue of warrants will describe the terms of the warrants, including, as applicable, the following:

We and the applicable warrant agent may amend or supplement the warrant agreement for a series of warrants without the consent of the holders of the warrants issued thereunder to effect changes that are not inconsistent with the provisions of the warrants and that do not materially and adversely affect the interests of the holders of the warrants.

We may issue rights to purchase common stock or preferred stock. This prospectus and any accompanying prospectus supplement will contain the material terms and conditions for each right. The accompanying prospectus supplement may add, update or change the terms and conditions of the rights as described in this prospectus.

We will describe in the applicable prospectus supplement the terms and conditions of the issue of rights being offered, the rights agreement relating to the rights and the rights certificates representing the rights, including, as applicable:

Each right will entitle the holder of rights to purchase for cash the principal amount of shares of common stock or preferred stock at the exercise price provided in the applicable prospectus supplement. Rights may be exercised at any time up to the close of business on the expiration date for the rights provided in the applicable prospectus supplement. After the close of business on the expiration date, all unexercised rights will be void.

Holders may exercise rights as described in the applicable prospectus supplement. Upon receipt of payment and the rights certificate properly completed and duly executed at the corporate trust office of the rights agent or any other office indicated in the prospectus supplement, we will, as soon as practicable, forward the shares of common stock or preferred stock purchasable upon exercise of the rights. If less than all of the rights issued in any rights offering are exercised, we may offer any unsubscribed securities directly to persons other than stockholders, to or through agents, underwriters or dealers or through a combination of such methods, including pursuant to standby underwriting arrangements, as described in the applicable prospectus supplement.

Each debt security, depositary share, warrant and right will be represented either by a certificate issued in definitive form to a particular investor or by one or more global securities representing the entire issuance of securities. Unless the applicable prospectus supplement provides otherwise, certificated securities will be issued in definitive form and global securities will be issued in registered form. Definitive securities name you or your nominee as the owner of the security, and in order to transfer or exchange these securities or to receive payments other than interest or other interim payments, you or your nominee must physically deliver the securities to the trustee, registrar, paying agent or other agent, as applicable. Global securities name a depositary or its nominee as the owner of the debt securities, depositary shares, warrants or rights represented by these global securities. The depositary maintains a computerized system that will reflect each investor's beneficial ownership of the

securities through an account maintained by the investor with its broker/dealer, bank, trust company or other representative, as we explain more fully below.

We may issue the registered debt securities, depositary shares, warrants and rights in the form of one or more fully registered global securities that will be deposited with a depositary or its nominee identified in the applicable prospectus supplement and registered in the name of that depositary or nominee. In those cases, one or more registered global securities will be issued in a denomination or aggregate denominations equal to the portion of the aggregate principal or face amount of the securities to be represented by registered global securities. Unless and until it is exchanged in whole for securities in definitive registered form, a registered global security may not be transferred except as a whole by and among the depositary for the registered global security, the nominees of the depositary or any successors of the depositary or those nominees.

If not described below, any specific terms of the depositary arrangement with respect to any securities to be represented by a registered global security will be described in the prospectus supplement relating to those securities. We anticipate that the following provisions will apply to all depositary arrangements.

Ownership of beneficial interests in a registered global security will be limited to persons, called participants, that have accounts with the depositary or persons that may hold interests through participants. Upon the issuance of a registered global security, the depositary will credit, on its book-entry registration and transfer system, the participants' accounts with the respective principal or face amounts of the securities beneficially owned by the participants. Any underwriters, dealers or agents participating in the distribution of the securities will designate the accounts to be credited. Ownership of beneficial interests in a registered global security will be shown on, and the transfer of ownership interests will be effected only through, records maintained by the depositary, with respect to interests of participants, and on the records of participants, with respect to interests of persons holding through participants. The laws of some states may require that some purchasers of securities take physical delivery of these securities in definitive form. These laws may impair your ability to own, transfer or pledge beneficial interests in registered global securities.

So long as the depositary, or its nominee, is the registered owner of a registered global security, that depositary or its nominee, as the case may be, will be considered the sole owner or holder of the securities represented by the registered global security for all purposes under the applicable indenture, deposit agreement, warrant agreement or rights agreement. Except as described below, owners of beneficial interests in a registered global security:

Accordingly, each person owning a beneficial interest in a registered global security must rely on the procedures of the depositary for that registered global security and, if that person is not a participant, on the procedures of the participant through which the person owns its interest, to exercise any rights of a holder under the applicable indenture, deposit agreement, warrant agreement or rights agreement.

We understand that under existing industry practices, if we request any action of holders or if an owner of a beneficial interest in a registered global security desires to give or take any action that a

holder is entitled to give or take under the applicable indenture, deposit agreement, warrant agreement or rights agreement, the depositary for the registered global security would authorize the participants holding the relevant beneficial interests to give or take that action, and the participants would authorize beneficial owners owning through them to give or take that action or would otherwise act upon the instructions of beneficial owners holding through them.

We will make payments of principal, premium, if any, and interest, if any, on debt securities, and any payments to holders with respect to depositary shares, warrants or rights, represented by a registered global security registered in the name of a depositary or its nominee to the depositary or its nominee, as the case may be, as the registered owner of the registered global security. None of us, the trustees, the depositaries for depositary shares, the warrant agents, the rights agents or any other agent of ours, agent of the trustees, agent of such depositaries, agent of the warrant agents or agent of the rights agents will have any responsibility or liability for any aspect of the records relating to, or payments made on account of, beneficial ownership interests in the registered global security or for maintaining, supervising or reviewing any records relating to those beneficial ownership interests.

We expect that the depositary for any of the securities represented by a registered global security, upon receipt of any payment of principal, premium, interest or other distribution of underlying securities or other property to holders on that registered global security, will immediately credit participants' accounts in amounts proportionate to their respective beneficial interests in that registered global security as shown on the records of the depositary. We also expect that standing customer instructions and customary practices will govern payments by participants to owners of beneficial interests in a registered global security held through the participants, as is now the case with the securities held for the accounts of customers registered in "street name." We also expect that any of these payments will be the responsibility of those participants.

If the depositary for any of the securities represented by a registered global security is at any time unwilling or unable to continue as depositary or ceases to be a clearing agency registered under the Securities Exchange Act of 1934, or Exchange Act, and a successor depositary registered as a clearing agency under the Exchange Act is not appointed by us within 90 days, we will issue securities in definitive form in exchange for the registered global security that had been held by the depositary. Any securities issued in definitive form in exchange for a registered global security will be registered in the name or names that the depositary gives to the relevant trustee, warrant agent, unit agent or other relevant agent of ours or theirs. It is expected that the depositary's instructions will be based upon directions received by the depositary from participants with respect to ownership of beneficial interests in the registered global security that had been held by the depositary.

We may sell the securities offered by this prospectus to one or more underwriters or dealers for public offering and sale by them or to investors directly or through agents. The accompanying prospectus supplement will set forth the terms of the offering and the method of distribution and will identify any firms acting as underwriters, dealers or agents in connection with the offering, including:

Only those underwriters identified in such prospectus supplement are deemed to be underwriters in connection with the securities offered in the prospectus supplement.

The distribution of the securities may be effected from time to time in one or more transactions at a fixed price or prices, which may be changed, or at prices determined as the applicable prospectus supplement specifies. The securities may be sold through an at the market offering, a rights offering, forward contracts or similar arrangements. In addition, we may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement so indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third party in such sale transactions will be an underwriter and, if not identified in this prospectus, will be named in the applicable prospectus supplement (or a post-effective amendment). In addition, we may otherwise loan or pledge securities to a financial institution or other third party that in turn may sell the securities short using this prospectus and an applicable prospectus supplement. Such financial institution or other third party may transfer its economic short position to investors in our securities or in connection with a concurrent offering of other securities.

In connection with the sale of the securities, underwriters, dealers or agents may be deemed to have received compensation from us in the form of underwriting discounts or commissions and also may receive commissions from securities purchasers for whom they may act as agent. Underwriters may sell the securities to or through dealers, and the dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters or commissions from the purchasers for whom they may act as agent.

We will provide in the applicable prospectus supplement information regarding any underwriting discounts or other compensation that we pay to underwriters or agents in connection with the securities offering, and any discounts, concessions or commissions that underwriters allow to dealers. Underwriters, dealers and agents participating in the securities distribution may be deemed to be underwriters, and any discounts, commissions or concessions they receive and any profit they realize on the resale of the securities may be deemed to be underwriting discounts and commissions under the Securities Act of 1933. Underwriters and their controlling persons, dealers and agents may be entitled,

under agreements entered into with us, to indemnification against and contribution toward specific civil liabilities, including liabilities under the Securities Act. Some of the underwriters, dealers or agents who participate in the securities distribution may engage in other transactions with, and perform other services for, us or our subsidiaries in the ordinary course of business.

Our common stock is currently listed on The NASDAQ Global Market, but any other securities may or may not be listed on a national securities exchange. To facilitate the offering of securities, certain persons participating in the offering may engage in transactions that stabilize, maintain or otherwise affect the price of the securities. This may include over-allotments or short sales of the securities, which involve the sale by persons participating in the offering of more securities than were sold to them. In these circumstances, these persons would cover such over-allotments or short positions by making purchases in the open market or by exercising their over-allotment option, if any. In addition, these persons may stabilize or maintain the price of the securities by bidding for or purchasing securities in the open market or by imposing penalty bids, whereby selling concessions allowed to dealers participating in the offering may be reclaimed if securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. These transactions may be discontinued at any time.

The validity of any securities offered by this prospectus will be passed upon for us by Pillsbury Winthrop Shaw Pittman LLP.

The consolidated financial statements of Upland Software, Inc., incorporated by reference in our Annual Report on Form 10-K for the year ended December 31, 2017, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon incorporated by reference therein, and incorporated herein by reference. Such financial statements are, and audited financial statements to be included in subsequently filed documents will be, incorporated herein in reliance upon the report of Ernst & Young LLP pertaining to such financial statements (to the extent covered by consents filed with the SEC) given on the authority of such firm as experts in accounting and auditing.

The audited financial statements of Rapide Communication Ltd. incorporated by reference in this prospectus and elsewhere in the registration statement have been so incorporated by reference in reliance upon the report of Grant Thornton UK LLP, independent auditors, upon the authority of said firm as experts in accounting and auditing.

The consolidated financial statements of our subsidiary, Qvidian Corporation, for the year ended December 31, 2016, included in our Current Report on Form 8-K/A filed with the SEC on January 26, 2018, have been audited by Moody, Famiglietti & Andronico, LLP, independent registered public accounting firm, as set forth in their report thereon included therein, and incorporated herein by reference. Such consolidated financial statements are, and audited financial statements to be included in subsequently filed documents will be, incorporated herein in reliance upon the report of Moody, Famiglietti & Andronico, LLP pertaining to such consolidated financial statements (to the extent covered by consents filed with the SEC) given on the authority of such firm as experts in accounting and auditing.

We have filed a registration statement on Form S-3 with the SEC under the Securities Act of 1933. This prospectus is part of the registration statement but the registration statement includes and incorporates by reference additional information and exhibits. We file annual, quarterly and current reports, proxy statements and other information with the SEC. You may read and copy the registration statement and any other document we file with the SEC at the public reference room maintained by the SEC at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information on the operation of the public reference room by calling the SEC at 1-800-SEC-0330. The SEC also maintains a website that contains reports, proxy and information statements and other information regarding companies, such as ours, that file documents electronically with the SEC. The address of that website is http://www.sec.gov. The information on the SEC's website is not part of this prospectus, and any references to this website or any other website are inactive textual references only.

The SEC permits us to "incorporate by reference" the information contained in documents we file with the SEC, which means that we can disclose important information to you by referring you to those documents rather than by including them in this prospectus. Information that is incorporated by reference is considered to be part of this prospectus and you should read it with the same care that you read this prospectus. Later information that we file with the SEC will automatically update and supersede the information that is either contained, or incorporated by reference, in this prospectus, and

will be considered to be a part of this prospectus from the date those documents are filed. We have filed with the SEC, and incorporate by reference in this prospectus:

We also incorporate by reference all additional documents that we file with the SEC under the terms of Section 13(a), 13(c), 14 or 15(d) of the Exchange Act that are made after the initial filing date of the registration statement of which this prospectus is a part and the effectiveness of the registration statement, as well as between the date of this prospectus and the termination of any offering of securities offered by this prospectus. We are not, however, incorporating, in each case, any documents or information that we are deemed to furnish and not file in accordance with SEC rules.

You may request a copy of any or all of the documents incorporated by reference but not delivered with this prospectus, at no cost, by writing or telephoning us at the following address and number: Investor Relations, Upland Software, Inc., 401 Congress Avenue, Suite 1850, Austin, TX 78701, telephone (512) 960-1031. We will not, however, send exhibits to those documents, unless the exhibits are specifically incorporated by reference in those documents.

	Price to Public		Underwriting Discounts and Commissions		Proceeds to Issuer

Per Share	$	42.00	$	2.10	$	39.90
Total	$	138,600,000.00	$	6,930,000.00	$	131,670,000.00


Credit Suisse		Jefferies
Canaccord Genuity		Needham & Company


William Blair		Craig-Hallum Capital Group		Raymond James		Roth Capital Partners		SunTrust Robinson Humphrey

		Page

Prospectus Supplement
ABOUT THIS PROSPECTUS SUPPLEMENT			ii
FORWARD-LOOKING STATEMENTS			iii
SUMMARY			S-1
RISK FACTORS			S-9
USE OF PROCEEDS			S-13
DILUTION			S-14
MATERIAL UNITED STATES FEDERAL INCOME AND ESTATE TAX CONSIDERATIONS FOR NON-U.S. HOLDERS			S-15
UNDERWRITING			S-20
LEGAL MATTERS			S-28
EXPERTS			S-28
WHERE YOU CAN FIND MORE INFORMATION			S-28
INCORPORATION BY REFERENCE			S-28
Prospectus
ABOUT THIS PROSPECTUS			2
RISK FACTORS			2
ABOUT UPLAND SOFTWARE, INC.			2
FORWARD-LOOKING STATEMENTS			4
USE OF PROCEEDS			5
DESCRIPTION OF DEBT SECURITIES			6
DESCRIPTION OF CAPITAL STOCK			13
DESCRIPTION OF DEPOSITARY SHARES			16
DESCRIPTION OF WARRANTS			18
DESCRIPTION OF RIGHTS			19
FORMS OF SECURITIES			19
PLAN OF DISTRIBUTION			22
LEGAL MATTERS			24
EXPERTS			24
WHERE YOU CAN FIND MORE INFORMATION			24

Underwriter		Number of Shares

Credit Suisse Securities (USA) LLC			1,254,000
Jefferies LLC			759,000
Canaccord Genuity LLC			495,000
Needham & Company, LLC			247,500
William Blair & Company L.L.C.			108,900
Craig-Hallum Capital Group LLC			108,900
Raymond James & Associates, Inc.			108,900
Roth Capital Partners, LLC			108,900
SunTrust Robinson Humphrey, Inc.			108,900

Total			3,300,000


Public offering price per share				$	42.00
Net tangible book value (deficit) per share as of March 31, 2019	$	(14.70	)
Increase in as adjusted net tangible book value (deficit) per share attributable to investors participating in this offering		7.27

As adjusted net tangible book value (deficit) per share after giving effect to this offering					(7.43	)

Dilution per share to investors in this offering				$	49.43

	Per Share				Total

	Without Option to Purchase Additional Shares		With Option to Purchase Additional Shares		Without Option to Purchase Additional Shares		With Option to Purchase Additional Shares
Underwriting discounts and commissions paid by us	$	2.10	$	2.10	$	6,930,000.00	$	7,969,500.00