As filed with the Securities and Exchange Commission on May 13, 2019.

Registration No. 333-231041

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

AMENDMENT NO. 1 TO

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Slack Technologies, Inc.

(Exact Name of Registrant as Specified in Its Charter)

Delaware	7372	26-4400325
(State or Other Jurisdiction of Incorporation or Organization)	(Primary Standard Industrial Classification Code Number)	(I.R.S. Employer Identification Number)

500 Howard Street

San Francisco, California 94105

(855) 980-5920

(Address, Including Zip Code, and Telephone Number, Including

Area Code, of Registrant’s Principal Executive Offices)

Stewart Butterfield

Chief Executive Officer

Slack Technologies, Inc.

500 Howard Street

San Francisco, California 94105

(855) 980-5920

(Name, address, including zip code, and telephone number, including

area code, of agent for service)

Copies to:
Richard A. Kline David W. Van Horne Sarah B. Axtell Goodwin Procter LLP Three Embarcadero Center San Francisco, California 94111 (650) 752-3100	David Schellhase Gabe Stern Amanda Westendorf Slack Technologies, Inc. 500 Howard Street San Francisco, California 94105 (855) 980-5920

Approximate date of commencement of proposed sale to the public:

As soon as practicable after this registration statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act, check the following box:  x

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.   ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

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

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

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

CALCULATION OF REGISTRATION FEE

Title of Each Class of Securities to be Registered	Amount to be Registered	Proposed Maximum Offering Price Per Share	Proposed Maximum Aggregate Offering Price(1)	Amount of Registration Fee(2)
Class A Common Stock, $0.0001 par value per share		Not applicable	$100,000,000	$12,120

(1) Estimated solely for purposes of calculating the registration fee pursuant to Rule 457(f)(2) of the Securities Act.

(2) The registrant previously paid $12,120 of the registration fee with the initial filing of this registration statement.

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. The securities may not be sold until the Registration Statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Subject to Completion, dated          , 2019 

SLACK TECHNOLOGIES, INC.

          Shares of Class A Common Stock

____________________________________________________________________________

This prospectus relates to the registration of the resale of up to          shares of our Class A common stock by our stockholders identified in this prospectus, or the Registered Stockholders. Unlike an initial public offering, the resale by the Registered Stockholders is not being underwritten by any investment bank. The Registered Stockholders may, or may not, elect to sell their shares of Class A common stock covered by this prospectus, as and to the extent they may determine. Such sales, if any, will be made through brokerage transactions on the New York Stock Exchange, or the NYSE. See the section titled “Plan of Distribution.” If the Registered Stockholders choose to sell their shares of Class A common stock, we will not receive any proceeds from the sale of shares of Class A common stock by the Registered Stockholders.

We have two classes of common stock, Class A common stock and Class B common stock. The rights of holders of Class A common stock and Class B common stock are identical, except voting and conversion rights. Each share of Class A common stock is entitled to one vote. Each share of Class B common stock is entitled to 10 votes and is convertible at any time into one share of Class A common stock. The holders of our outstanding Class B common stock hold approximately     % of the voting power of our outstanding capital stock, with our directors and executive officers and their affiliates holding approximately     %.

Prior to any sales of shares of Class A common stock, Registered Stockholders who hold Class B common stock must convert their shares of Class B common stock into shares Class A common stock.

No public market for our Class A common stock currently exists. However, our shares of Class B common stock (on an as converted basis) have a history of trading in private transactions. Based on information available to us, the low and high sales price per share of Class B common stock (on an as converted basis) for such private transactions during the year ended January 31, 2019 was $8.37 and $23.41, respectively, and during the period from February 1, 2019 through          , 2019 was $          and $          , respectively. For more information, see the section titled “Sale Price History of our Capital Stock.” Our recent trading prices in private transactions may have little or no relation to the opening public price of our shares of Class A common stock on the NYSE or the subsequent trading price of our shares of Class A common stock on the NYSE. Further, the listing of our Class A common stock on the NYSE without underwriters is a novel method for commencing public trading in shares of our Class A common stock, and consequently, the trading volume and price of shares of our Class A common stock may be more volatile than if shares of our Class A common stock were initially listed in connection with an underwritten initial public offering.

Based on information provided by the NYSE, the opening public price of our Class A common stock on the NYSE will be determined by buy and sell orders collected by the NYSE from broker-dealers. Based on such orders, the designated market maker will determine an opening price for our Class A common stock in consultation with a financial advisor pursuant to applicable NYSE rules. For more information, see the section titled “Plan of Distribution.”

We have applied to list our Class A common stock on the NYSE under the symbol “SK.” We expect our Class A common stock to begin trading on the NYSE on or about          , 2019.

We are an “emerging growth company” as defined under the federal securities laws and, as such, we have elected to comply with reduced reporting requirements for this prospectus and may elect to do so in future filings.

See the section titled “Risk Factors” beginning on page 14 to read about factors you should consider before buying shares of our Class A common stock.

The Securities and Exchange Commission and state securities regulators have not approved or disapproved these securities, or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

, 2019

TABLE OF CONTENTS

About This Prospectus	i
Prospectus Summary	1
Risk Factors	14
Special Note Regarding Forward-Looking Statements	55
Market and Industry Data	57
Use of Proceeds	58
RSU Sales	58
Dividend Policy	59
Capitalization	60
Selected Consolidated Financial Data and Other Data	62
Management’s Discussion and Analysis of Financial Condition and Results of Operations	65
Business	93
Management	124
Executive Compensation	132
Certain Relationships and Related Party Transactions	141
Principal and Registered Stockholders	148
Description of Capital Stock	153
Shares Eligible for Future Sale	160
Sale Price History of our Capital Stock	162
Certain Material U.S. Federal Income Tax Consequences	163
Plan of Distribution	167
Legal Matters	169
Experts	169
Additional Information	169
Index to Consolidated Financial Statements	F-1

_______________

You should rely only on the information contained in this prospectus or contained in any free writing prospectus filed with the Securities and Exchange Commission, or the SEC. Neither we nor any of the Registered Stockholders have authorized anyone to provide any information or make any representations other than those contained in this prospectus or in any free writing prospectus we have prepared. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. The Registered Stockholders are offering to sell, and seeking offers to buy, shares of their Class A common stock only in jurisdictions where offers and sales are permitted. The information contained in this prospectus is accurate only as of the date of this prospectus, regardless of the time of delivery of this prospectus or of any sale of the Class A common stock. Our business, financial condition, results of operations, and prospects may have changed since such date.

For investors outside of the United States: Neither we nor any of the Registered Stockholders have done anything that would permit the use of or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. You are required to inform yourselves about, and to observe any restrictions relating to, the offering of Class A common stock by the Registered Stockholders and the distribution of this prospectus outside of the United States.

ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement on Form S-1 that we filed with the SEC using a “shelf” registration or continuous offering process. Under this shelf process, the Registered Stockholders may, from time to time, sell the Class A common stock covered by this prospectus in the manner described in the section titled “Plan of Distribution.” Additionally, we may provide a prospectus supplement to add information to, or update or change information contained in, this prospectus, including the section titled “Plan of Distribution.” You may obtain this information without charge by following the instructions under the section titled “Additional Information” appearing elsewhere in this prospectus. You should read this prospectus and any prospectus supplement before deciding to invest in our Class A common stock.

i

PROSPECTUS SUMMARY

This summary highlights selected information that is presented in greater detail elsewhere in this prospectus. This summary does not contain all of the information you should consider before investing in our Class A common stock. You should read this entire prospectus carefully, including the sections titled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our consolidated financial statements and the related notes included elsewhere in this prospectus, before making an investment decision. Unless the context otherwise requires, the terms “Slack,” “the company,” “we,” “us” and “our” in this prospectus refer to Slack Technologies, Inc. and its consolidated subsidiaries. Our fiscal year ends January 31.

SLACK TECHNOLOGIES, INC.

Introduction – What is Slack?

Slack is where work happens.

Around the world, over 600,000 organizations in over 150 countries have turned to Slack as the place to communicate, collaborate, and get work done. Over 10 million people inside those organizations – accountants, customer support reps, engineers, lawyers, journalists, dentists, chefs, detectives, executives, scientists, farmers, hoteliers, salespeople, and many others – collectively spend more than 50 million hours in active use of Slack in a typical week, on either a free or paid subscription plan. They do so because Slack is a new layer of the business technology stack that brings together people, applications, and data – a single place where people can effectively work together, access hundreds of thousands of critical applications and services, and find important information to do their best work.

History

We created Slack initially as an internal tool to help our own team stay on the same page, to be able to easily access conversations, decisions, data, and content that had been shared, and to tap into a variety of software applications from one place. We were frustrated with email. It created fragmented silos of inaccessible information, hidden in individual inboxes. When new members joined the team, they were cut off from the rich history of communication that occurred before they arrived. Transparency was difficult to achieve and routine communication had to be supplemented with status reports and stand-up meetings in order to keep the team coordinated.

In addition, despite the fact that email was the universal default routing mechanism for enterprise software, it was also an ineffective medium for sharing and managing the information and activity generated by that software. The notifications and simple workflows, such as approval processes, generated by customer support ticketing tools, human resources management systems, and expense trackers, disappeared into individual inboxes. Email is static and offers no direct integration with any of these tools. In short, email was a tiny window into the vast landscape of business information and software available to us collectively, and we needed to see the whole picture.

We needed a new way to work that would help us make the most of both our people and our significant investment in software. What was available was incomplete, inadequate, and unfit for our work at hand. What we needed did not exist. So we built it.

Since our public launch in 2014, it has become apparent that organizations worldwide have similar needs, and are now finding the solution with Slack. Our growth is largely due to word-of-mouth recommendations. Slack usage inside organizations of all kinds is typically initially driven bottoms-up, by end users. Despite this, we (and the rest of the world) still have a hard time explaining Slack. It’s been called an operating system for teams, a hub for collaboration, a connective tissue across the organization, and much else. Fundamentally, it is a new layer of the business technology stack in a category that is still being defined.

Slack’s Role

The most helpful explanation of Slack is often that it replaces the use of email inside the organization. Like email (or the Internet or electricity), Slack has very general and broad applicability. It is not aimed at any one specific purpose, but nearly anything that people do together at work.

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Unlike email, however, most of this activity happens in team-based channels, rather than in individual inboxes. Channels offer a persistent record of the conversations, data, documents, and application workflows relevant to a project or a topic. Membership of a channel can change over time as people join or leave a project or organization, and users benefit from the accumulated historical information in a way an employee never could when starting with an empty email inbox. Depending on the size of the organization, this might provide tens, hundreds or even thousands of times more access to information than is available to individuals working in environments where email is the primary means of communication.

Also unlike email, Slack was designed from the ground up to integrate with external software systems. Slack provides an easy way for users to share and aggregate information from other software, take action on notifications, and advance workflows in a multitude of third-party applications, over 1,500 of which are listed in the Slack App Directory. Further, Slack’s platform capabilities extend beyond integrations with third-party applications and allow for easy integrations with an organization’s internally-developed software. During the three months ended January 31, 2019, our more than 10 million daily active users included more than 500,000 registered developers. Developers have collectively created more than 450,000 third-party applications or custom integrations that were used in a typical week during the three months ended January 31, 2019. Additionally, we are currently developing low-code solutions to create integrations and workflows entirely in Slack, suitable for all users and based on a simple, non-technical user interface.

Ultimately, Slack is more than email replacement. It is a new layer of technology that brings together people, applications, and data. Just as an operating system coordinates the flow of information and resources of a computer in a centralized fashion, using Slack inside an organization creates a hub into which critical business information flows, is acted upon and transformed, and is then quickly routed to its desired destination. Slack streamlines our users’ workflows, increases the beneficial return on the time they spend communicating, and creates a powerful point of leverage for increased productivity.

Business Context

We believe Slack is positioned extremely well to benefit from the explosive proliferation of software into every aspect of business and the increased pace of disruption driven by technological change.

According to Netskope, a typical enterprise uses more than 1,000 cloud services. Many of the largest IT departments maintain thousands of enterprise applications. All of this software either automates the repetitive and often error-prone work that humans used to do or augments human effort with entirely new capabilities.

With the simpler and more routine tasks automated away, the work that remains is more sophisticated and complex. Those tasks, which most rely on human judgment, intelligence, and creativity, are both more difficult to perform and more difficult to coordinate. Organizational alignment becomes harder to achieve. Further, the increased use of highly specialized software in different functional areas leads to a fragmentation of attention and, because it is often difficult to share objects or records with non-users, impedes the flow of important information across the organization.

These challenges compound the disruptive threats companies face in increasingly dynamic environments. Technological change and increased globalization continually create new opportunities and threats, but they also accelerate second-order change in customer needs, competitors’ behavior, and overall macroeconomic conditions. This environment demands an ever-greater ability to adapt and respond. In an increasingly dynamic world, the fundamental business advantage is organizational agility – the ability for individuals, teams, and organizations to maintain alignment while continually transforming to meet evolving challenges.

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How Slack Helps

Slack is designed to allow people and teams to realize their full potential at work and, in doing so, to help organizations overcome the challenges created by their increased reliance on a proliferation of specialized software and radically reduce the communication and coordination effort required to achieve a given amount of organizational agility.

Our vision is a world where organizational agility is easy to achieve, regardless of an organization’s size

As a result of the alignment teams and organizations are able to maintain while continuously adapting to respond in increasingly dynamic environments, less effort and energy is wasted and the human beings on those teams are able to fully utilize their intelligence and creativity in pursuit of the organization’s shared objectives.

Slack makes existing software more useful and accessible

As a flexible platform for routing information of all kinds, Slack integrates horizontally with thousands of other applications, from those provided by companies like Google, Salesforce, ServiceNow, Atlassian, and Dropbox to the proprietary line-of-business applications developed by organizations for their own internal use. This functionality enables users to securely interact with all of these applications in one familiar user interface. We enable organizations that use Slack to get more out of their software investment.

Slack drives increased organizational agility

As a new layer of business technology that brings together an organization’s people, applications, and data, Slack improves organizational alignment. In a December 2018 survey that we conducted with more than a thousand U.S.-based users who had been using Slack for at least one month, which we refer to as our 2018 Survey, 87% reported that Slack improved communication and collaboration inside their organization.

Summary of Key Benefits

Working in Slack provides several key benefits to users, teams, and organizations and to our platform ecosystem:

• People love using Slack and that leads to high levels of engagement.Slack is enterprise software created with an eye for user experience usually associated with consumer products. We believe that the more simple, enjoyable, and intuitive the product is, the more people will want to use it. As a result, teams benefit from the aggregated attention that happens when all members of a team are engaged in a single collaboration tool.

• Slack increases an organization’s “return on communication.”Moving to channel-based communication increases accessibility of communication, which in turn increases transparency and breaks down silos. The organization benefits from increased coordination and alignment from a given amount of communication, with no additional effort in the form of status reports, update meetings, and so on.

• Slack increases the value of existing software investment. Integration with Slack increases both the accessibility of information inside applications and the response times for many basic actions. Because Slack users can do virtually everything on Slack on mobile that they can do on desktop, they do not need to have dozens of work applications on their mobile devices to be able to make lightweight use of those applications on the go.

• An organization’s archive of data increases in value over time.As teams continue to use Slack, they build a valuable resource of widely accessible information. Important messages are surrounded by useful context and users can see how fellow team members created and worked with the information and arrived at a decision. New employees can have instant access to the information they need to be effective whenever they join a new team or company. Finally, the content on Slack is available through powerful search and discovery tools, powered by machine learning, which improve through usage.

• Slack helps organizations improve culture and employees’ feelings of empowerment. When every member of a team learns from, and contributes towards, common goals, people feel they have greater influence over

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the ultimate outcomes of their work. By keeping all team members in the information flow, we believe that Slack increases this sense that members of a team can have an impact and make a difference and that creates greater team cohesion and increases motivation.

• Slack helps achieve organizational agility.Slack’s channels immerse workers directly into the dynamic and evolving communication, decision making, and data flow that defines modern work. Because workers have both more access to data updated in real time and more context for that data, they are better able to quickly react and adjust work streams in response to new business priorities or changing conditions while staying in alignment with one another.

• Developers are better able to reach and deliver value to their customers.Slack has aggregated hundreds of thousands of organizations on one platform and made it easier for developers to distribute their software to any Slack-using organization. By making information from their applications available and allowing users to perform key actions through a whole new interface, developers can make their customers happier and more engaged.

We believe that whoever makes it easiest for teams to function with agility and cohesion in an ever more complex world will be the most important software company in the world. We aim to be that company.

Our Business Model

From the outset, our go-to-market strategy has centered around offering an exceptional product and level of service to organizations on Slack. We offer a self-service approach, for both free and paid subscriptions to Slack, which capitalizes on strong word-of-mouth adoption and customer love for our brand. Since 2016, we have augmented our approach with a direct sales force and customer success professionals who are focused on driving successful adoption and expansion within organizations, whether on a free or paid subscription plan.

We define daily active users as users who either created or consumed content in a given 24-hour period on either a free or paid subscription plan. We define an organization on Slack as a separate entity, such as a company, educational or government institution, or distinct business unit of a company, that is on a subscription plan, whether free or paid. Once an organization has three or more users on a paid subscription plan, we count them as a Paid Customer.

Our user base has grown rapidly since our launch in 2014. During the three months ended January 31, 2019, our daily active users exceeded 10 million. As of January 31, 2019, Slack had more than 600,000 organizations with three or more users, comprised of:

• More than 88,000 Paid Customers, including more than 65 companies in the Fortune 100; and

• More than 500,000 organizations on our Free subscription plan.

Many of our Paid Customers have thousands of active users and our largest Paid Customers have tens of thousands of employees using Slack on a daily basis.

Our users, whether on a free or paid subscription plan, are highly engaged, and their collective active use of Slack for the week ended January 31, 2019 exceeded 50 million hours. During the week ended January 31, 2019, more than 1 billion messages were sent in Slack. During this same time, on a typical workday, users at Paid Customers averaged nine hours connected to Slack through at least one device and spent more than 90 minutes actively using Slack.

Our direct sales and customer success efforts are focused on larger organizations who have a greater number of users and teams and have the potential to increase spend over time. We measure the number of Paid Customers >$100,000 of annual recurring revenue, or ARR, as a gauge of adoption within and expansion into large enterprises. We had 575 Paid Customers >$100,000 of ARR as of January 31, 2019, which accounted for approximately 40% of our revenue in fiscal year 2019.

We generate revenue primarily from the sale of subscriptions for Slack. Paid customers typically pay on a monthly or annual basis, based on the number of users that they have on Slack.

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Our revenue was $105.2 million, $220.5 million, and $400.6 million in fiscal years 2017, 2018, and 2019, respectively, representing annual growth of 110% and 82%, respectively. Our growth is global with international revenue representing 34%, 34%, and 36% of total revenue in fiscal years 2017, 2018, and 2019, respectively. We continue to invest in growing our business to capitalize on our market opportunity. As a result, we incurred net losses of $146.9 million, $140.1 million, and $138.9 million in fiscal years 2017, 2018, and 2019, respectively. Our net losses have been decreasing as a percentage of revenue over time as revenue growth has outpaced the growth in operating expenses.

Expansion within organizations on Slack is a significant contributor to our growth. We measure the rate of expansion within our Paid Customer base,both sales-driven and through organic growth,by Net Dollar Retention Rate. Our Net Dollar Retention Rate was 143% as of January 31, 2019. We believe that our Net Dollar Retention Rate is a reflection of the rapid pace of adoption that often occurs as usage spreads within and across teams. We believe that all of these factors will contribute to a high lifetime value of an organization on Slack. For a definition of how we calculate Net Dollar Retention Rate and additional information about our key business metrics, see the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Key Business Metrics.”

What Sets Us Apart

Singular focus

Our development, design, partnerships, customer engagement, and investments are targeted at realizing the enormity and simplicity of Slack’s singular mission: to make people’s working lives simpler, more pleasant, and more productive. We have no legacy products or competing priorities.

Scale and market leadership

The strength of our market leadership is demonstrated by the scale and growth of our users, the high level of engagement within our user base, our growth within organizations, the breadth of applications that integrate with Slack, and the size of our developer ecosystem.

Strong increasing returns dynamics

As Slack usage increases inside an organization, more value is created for each additional user who might join, as well as for all existing users.We believe shared channels between organizations will increase the value of the overall Slack network for each new organization that joins as well as for all existing network members. Slack also generates more value for developers as more users and more organizations join Slack, and users and organizations are more attracted to Slack as more apps are integrated into or built on our platform.

Customer love leading to stickiness and organic expansion

People love using Slack and many become advocates for wider use inside of their organizations. They also tend to recommend Slack when they switch jobs or join organizations that are not yet using Slack. This customer love is a source of growth that is exceptional in enterprise software.

Differentiated go-to-market strategy

Organic growth is generated as users realize the benefits of Slack. This growth enables us to attract new and prospective organizations through a highly effective self-service customer engagement model for free and paid subscription plans.We complement our self-service strategy with a focused direct sales effort and our customer success teams work to broaden adoption of Slack into wider-scale deployments.

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Customer-centricity as the fundamental tenet of our company

We build our software and user interface around the real needs of human beings.We focus maniacally on customer support for free and paid subscription plans and treat it as a critical and strategic imperative for our company. We believe people should leave every interaction with a Slack representative feeling that they have been heard, respected, and helped by a human being who truly understands Slack.

Market Opportunity

We believe everyone whose working life is mediated by email is a potential Slack user. Indeed, because of the universal need for organizational agility and the impact to current and potential organizations on Slack of getting more out of their investment in software, we further believe that the shift to Slack, or services like Slack, is inevitable.We estimate the market opportunity for Slack and other providers of workplacebusiness technology software platforms for communication and collaboration to be $28 billion.As our market and the number of competitors in it is rapidly evolving, our estimates for the size of this market may not be reflective of the actual size of the market.

Growth Strategy

We intend to continue to grow by the following means:

Expand our user base through continuous enhancements to Slack

We will continue a relentless focus on product design and new user experience to reach more users and organizations.

Grow the number of organizations on Slack and increase our paid customers

We believe our market remains underpenetrated and we will continue to expand our marketing and sales efforts to reach more users and organizations and to increase the number of paid customers.

Increase usage within organizations on Slack

We plan to continueto grow use and users within organizations on Slack by increasing our investments in our direct sales force, customer success, and customer experience teams, along with new user education initiatives.

Enable Slack usage across existing and new business networks

Slack’s guest accounts and shared channels features facilitate secure collaboration between companies and we believe adoption of these features will grow significantly in the coming years. We expect the associated network effects will increase the value of Slack both for existing and new organizations on Slack and will be an important factor in our future growth.

Further invest in enterprise capabilities

We intend to increase investments in marketing, expand our field sales team, and continue to build product functionality in order to drive greater adoption of Slack by large organizations.

Invest in international expansion

We plan to open offices and hire sales and customer experience people in additional countries and expand our presence in countries where we already operate.

Grow our application platform and developer ecosystem

We will continue investing to expand the number of developers building applications that integrate with Slack and to make Slack work with an increasing number of third-party and internally developed custom applications.

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Leverage artificial intelligence, machine learning and advanced search

We believe that there is a significant opportunity tofurther streamline people’s working lives by automating workflows, and we intend to continue to invest in our research and development efforts in artificial intelligence, machine learning, and search capabilities.

Estimated Preliminary Results for the Three Months Ended April 30, 2019 (unaudited)

Set forth below are certain estimated preliminary financial results and other key business metrics for the three months ended April 30, 2019. These ranges are based on the information available to us at this time. We have provided ranges, rather than specific amounts, because these results are preliminary. Our actual results may vary from the estimated preliminary results presented here due to the completion of our financial closing procedures, final adjustments and other developments that may arise between now and the time the financial results for the three months ended April 30, 2019 are finalized.

These are forward-looking statements and may differ from actual results. These estimates should not be viewed as a substitute for our full interim or annual financial statements prepared in accordance with GAAP. Accordingly, you should not place undue reliance on this preliminary data. See the section titled “Special Note Regarding Forward-Looking Statements.” These estimated preliminary results should be read in conjunction with the sections titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and “Selected Consolidated Financial Data and Other Data” and our consolidated financial statements and related notes included elsewhere in this prospectus.

	Three Months Ended
	April 30, 2018			April 30, 2019
				Low			High
	(Dollars in thousands)
Financial Information:
Revenue	$	80,919		$	133,800		$	134,800
Loss from operations	$	(26,328	)	$	(39,400	)	$	(38,400	)
Calculated Billings	$	102,080		$	147,700		$	149,700
Net Dollar Retention Rate	149		%	138%

• For the three months ended April 30, 2019, we expect revenue to be between $133.8 million and $134.8 million , as compared to revenue of $80.9 million for the three months ended April 30, 2018, an increase of 66% at the midpoint. The increase in revenue was primarily due to expansion within our existing Paid Customers as reflected by our expected Net Dollar Retention Rate of 138% as of April 30, 2019, and the addition of new Paid Customers.

• For the three months ended April 30, 2019, we expect loss from operations to be between $39.4 million and $38.4 million , as compared to loss from operations of $26.3 million for the three months ended April 30, 2018. The increase in loss from operations reflects an increase in operating expenses to support the growth and expansion of our business and continued investment in product development.

• For the three months ended April 30, 2019, we expect Calculated Billings to be between $147.7 million and $149.7 million , as compared to Calculated Billings of $102.1 million for the three months ended April 30, 2018, an increase of 46% at the midpoint. The increase in Calculated Billings is primarily due to higher sales of subscriptions to both our existing and new Paid Customers .

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The following table reconciles revenue to Calculated Billings:

	Three Months Ended
	April 30, 2018			April 30, 2019
				Low			High
	(In thousands)
Revenue	$	80,919		$	133,800		$	134,800
Add: Total deferred revenue, end of period	146,614			255,773			256,773
Less: Total deferred revenue, beginning of period	(125,453		)	(241,873		)	(241,873		)
Calculated Billings	$	102,080		$	147,700		$	149,700

• As of April 30, 2019, we expect our Net Dollar Retention Rate to be 138%, as compared to our Net Dollar Retention Rate of 149% as of April 30, 2018. The decrease in Net Dollar Retention Rate reflects growth in our base of revenue and our penetration within existing, long-term Paid Customers has increased.

See the sections titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations— Key Business Metrics and—Non-GAAP Financial Measures” for more information on Calculated Billings and Net Dollar Retention Rate.

This data has been prepared by, and is the responsibility of, management. Our independent registered public accounting firm, KPMG LLP, has not audited, reviewed, or performed any procedures with respect to the estimated preliminary financial results. Accordingly, KPMG LLP does not express an opinion or any other form of assurance with respect thereto.

Risk Factors Summary

Our business is subject to numerous risks and uncertainties, including those highlighted in the section titled “Risk Factors.” These risks include, but are not limited to, the following:

• We have a limited operating history, which makes it difficult to forecast our revenue and evaluate our business and future prospects.

• We have a history of net losses, we anticipate increasing operating expenses in the future, and we may not be able to achieve and, if achieved, maintain profitability.

• We have experienced rapid growth in recent periods and our recent growth rates may not be indicative of our future growth.

• If we fail to manage our growth effectively, we may be unable to execute our business plan or maintain high levels of service and customer satisfaction.

• We may experience quarterly fluctuations in our results of operations due to a number of factors that make our future results difficult to predict and could cause our results of operations to fall below analyst or investor expectations.

• Real or perceived errors, failures, vulnerabilities, or bugs in Slack could harm our business, results of operations, and financial condition.

• The market and software categories in which we participate are competitive, new, and rapidly changing, and if we do not compete effectively with established companies as well as new market entrants our business, results of operations, and financial condition could be harmed.

• If we are unable to attract new users and organizations, convert users of and organizations on our free version into paid customers, grow or maintain our Net Dollar Retention Rate, expand usage within organizations on Slack, and sell premium subscription plans or develop new features, integrations, capabilities, and enhancements that achieve market acceptance, our revenue growth and profitability will be harmed.

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• Our ability to introduce new features, integrations, capabilities, and enhancements is dependent on adequate research and development resources. If we do not adequately fund our research and development efforts, or if our research and development investments do not translate into material enhancements to Slack, we may not be able to compete effectively and our business, results of operations, and financial condition may be harmed.

• If there are interruptions or performance problems associated with the technology or infrastructure used to provide Slack, organizations on Slack may experience service outages, other organizations may be reluctant to adopt Slack, and our reputation could be harmed.

• A security incident may allow unauthorized access to our systems, networks, or data or the data of organizations on Slack, harm our reputation, create additional liability, and harm our financial results.

• Any actual or perceived failure by us to comply with privacy, data protection, information security, consumer privacy, data residency, or telecommunications laws, regulations, government access requests, and obligations in one or multiple jurisdictions could result in proceedings, actions, or penalties against us and could harm our business and reputation. These laws are uncertain, evolving, and interpreted and applied in different ways in different countries and, as a result, our legal obligations in different countries, and our efforts to comply with those legal obligations, may be inadequate or in conflict.

• Our listing differs significantly from an underwritten initial public offering.

• The public price of our Class A common stock may be volatile, and could, upon listing on the NYSE, decline significantly and rapidly.

• The dual class structure of our common stock has the effect of concentrating voting control with those stockholders who held our capital stock prior to the listing of our Class A common stock on the NYSE, including our directors, executive officers and their respective affiliates, who will hold in the aggregate          % of the voting power of our capital stock upon the effectiveness of the registration statement of which this prospectus forms a part. This ownership will limit or preclude your ability to influence corporate matters, including the election of directors, amendments of our organizational documents, and any merger, consolidation, sale of all or substantially all of our assets, or other major corporate transaction requiring stockholder approval.

• None of our stockholders are party to any contractual lock-up agreement or other contractual restrictions on transfer. Following our listing, sales of substantial amounts of our Class A common stock in the public markets or the perception that sales might occur, could cause the market price of our Class A common stock to decline.

Channels for Disclosure of Information

Investors, the media, and others should note that, following the effectiveness of the registration statement of which this prospectus forms a part, we intend to announce material information to the public through filings with the SEC, the investor relations page on our website, blog posts on our website, press releases, public conference calls, webcasts, our twitter feed (@SlackHQ), our Facebook page, and our LinkedIn page.

The information disclosed by the foregoing channels could be deemed to be material information. As such, we encourage investors, the media, and others to follow the channels listed above and to review the information disclosed through such channels.

Any updates to the list of disclosure channels through which we will announce information will be posted on the investor relations page on our website.

Corporate Information

We were incorporated in 2009 as Tiny Spec, Inc., a Delaware corporation. Later in 2009, we changed our name to Tiny Speck, Inc. and, in 2014, we changed our name to Slack Technologies, Inc. Our principal executive offices are located at 500 Howard Street, San Francisco, California 94105, and our telephone number is (855) 980-5920. Our website address is www.slack.com. Information contained on or that can be accessed through our website does not

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constitute part of this prospectus and the inclusion of our website address in this prospectus is an inactive textual reference only.

“Slack” is our registered trademark in the United States, Australia, Brazil, Canada, the European Union, Japan, Mexico, New Zealand, Russia, and South Korea. Other trademarks and trade names referred to in this prospectus are the property of their respective owners.

Emerging Growth Company

The Jumpstart Our Business Startups Act, or the JOBS Act, was enacted in April 2012 with the intention of encouraging capital formation in the United States and reducing the regulatory burden on newly-public companies that qualify as “emerging growth companies.” We are an “emerging growth company” within the meaning of the JOBS Act. As an “emerging growth company,” we intend to take advantage of certain exemptions from various public reporting requirements, including the requirement that our internal control over financial reporting be audited by our independent registered public accounting firm pursuant to Section 404 of the Sarbanes-Oxley Act of 2002, or the Sarbanes-Oxley Act, certain requirements related to the disclosure of executive compensation in this prospectus and in our periodic reports and proxy statements, and the requirement that we hold a non-binding advisory vote on executive compensation and any golden parachute payments. We may take advantage of these exemptions until we are no longer an “emerging growth company.”

In addition, under the JOBS Act, “emerging growth companies” can delay adopting new or revised accounting standards until such time as those standards apply to private companies. We intend to avail ourselves of this exemption from new or revised accounting standards. Accordingly, we will not be subject to the same new or revised accounting standards as other public companies that are not “emerging growth companies.”

We will remain an “emerging growth company” until the earliest to occur of: (i) the last day of the fiscal year in which we have more than $1.07 billion in annual revenue; (ii) the date we qualify as a “large accelerated filer,” with at least $700 million of equity securities held by non-affiliates; (iii) the date on which we have issued, in any three-year period, more than $1.0 billion in non-convertible debt securities; and (iv) the last day of the fiscal year ending after the fifth anniversary of the listing of our Class A common stock on the NYSE.

For certain risks related to our status as an “emerging growth company,” see the section titled “Risk Factors—Risks Related to Our Business—We are an ‘emerging growth company,’ and the reduced disclosure requirements applicable to ‘emerging growth companies’ may make our Class A common stock less attractive to investors.”

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SUMMARY CONSOLIDATED FINANCIAL DATA AND OTHER DATA

The following tables summarize our consolidated financial data and other data. The summary consolidated statements of operations data for the years ended January 31, 2017, 2018, and 2019 and consolidated balance sheet data as of January 31, 2019 have been derived from our audited consolidated financial statements included elsewhere in this prospectus. Our historical results are not necessarily indicative of the results that may be expected in the future. You should read the following summary consolidated financial data and other data below in conjunction with the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our consolidated financial statements and related notes included elsewhere in this prospectus.

	Year Ended January 31,
	2017			2018			2019
	(In thousands, except per share data)
Consolidated Statements of Operations Data:
Revenue	$	105,153		$	220,544		$	400,552
Cost of revenue(1)	15,517			26,364			51,301
Gross profit	89,636			194,180			349,251
Operating expenses:
Research and development(1)	96,678			141,350			157,538
Sales and marketing(1)	104,006			140,188			233,191
General and administrative(1)	37,455			56,493			112,730
Total operating expenses	238,139			338,031			503,459
Loss from operations	(148,503		)	(143,851		)	(154,208		)
Other income (expense), net	1,749			4,581			16,146
Loss before income taxes	(146,754		)	(139,270		)	(138,062		)
Provision for income taxes	155			793			840
Net loss	(146,909		)	(140,063		)	(138,902		)
Net income (loss) attributable to noncontrolling interest(2)	(45		)	22			1,781
Net loss attributable to Slack	(146,864		)	(140,085		)	(140,683		)
Less: Deemed dividends to preferred stockholders	—			40,883			—
Net loss attributable to Slack common stockholders	$	(146,864	)	$	(180,968	)	$	(140,683	)
Basic and diluted net loss per share:
Net loss per share attributable to Slack common stockholders, basic and diluted(3)	$	(1.28	)	$	(1.47	)	$	(1.16	)
Weighted-average shares used in computing net loss per share attributable to Slack common stockholders, basic and diluted(3)	114,887			122,865			121,732
Pro forma net loss per share attributable to Slack common stockholders, basic and diluted (unaudited)(3)							$	(0.27	)
Weighted-average shares used in computing pro forma net loss per share attributable to Slack common stockholders, basic and diluted (unaudited)(3)							517,493

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__________________

(1) Includes stock-based compensation as follows:

	Year Ended January 31,
	2017		2018		2019
	(In thousands)
Cost of revenue	$	630	$	491	$	732
Research and development	34,546		35,260		9,948
Sales and marketing	9,744		8,044		2,677
General and administrative	5,171		4,288		9,775
Total stock-based compensation	$	50,091	$	48,083	$	23,132

Stock-based compensation for fiscal years 2017, 2018, and 2019 included compensation expense of $26.5 million, $0, and $14.8 million, respectively, related to secondary sales of common stock by certain of our current and former employees and $8.0 million, $39.4 million, and $0, respectively, related to cash payments attributable to tender offers and repurchases for our outstanding common stock.

(2) Our consolidated financial statements include our majority-owned subsidiary, Slack Fund L.L.C., or Slack Fund. The ownership interest of minority investors in Slack Fund is recorded as a noncontrolling interest.

(3) See note 10 to our consolidated financial statements included elsewhere in this prospectus for an explanation of the method used to calculate basic and diluted net loss per share attributable to Slack common stockholders and pro forma basic and diluted net loss per share attributable to Slack common stockholders and the weighted-average number of shares used in the computation of the per share amounts.

	As of January 31, 2019
	Actual		Pro Forma(1)
	(In thousands)
Consolidated Balance Sheet Data:
Cash, cash equivalents, and marketable securities	$	841,071	$	841,071
Working capital	650,324		650,324
Total assets	1,198,956		1,198,956
Total deferred revenue	241,873		241,873
Convertible preferred stock	1,392,101		—
Total stockholders’ equity	841,606		841,606

__________________

(1) The pro forma column in the consolidated balance sheet data table above reflects (a) the automatic conversion of all outstanding shares of our convertible preferred stock into 373,371,712 shares of Class B common stock as if such conversion had occurred on January 31, 2019, (b) the vesting and settlement of 22,388,531 restricted stock units, or RSUs, for which the service-based condition was fully satisfied as of January 31, 2019 and for which we expect the performance vesting condition to be satisfied upon the listing and public trading of our Class A common stock on the NYSE, and (c) stock-based compensation of $157.5 million associated with outstanding RSUs as of January 31, 2019 for which we expect the performance vesting condition to be satisfied upon the listing and public trading of our Class A common stock on the NYSE. Payroll taxes and other withholding obligations have not been included in the pro forma column. For additional information, see Note 1 to our consolidated financial statements included elsewhere in this prospectus and in the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Significant Impacts of Stock-Based Compensation.”

Key Business Metrics

We review the following key business metrics to measure our performance, identify trends, formulate financial projections, and make strategic decisions. We are not aware of any uniform standards for calculating these key metrics, which may hinder comparability with other companies who may calculate similarly-titled metrics in a different way.

	As of January 31,
	2017		2018		2019
Paid Customers	37,000		59,000		88,000
Paid Customers >$100,000	135		298		575
Net Dollar Retention Rate	171	%	152	%	143	%

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For additional information about our key business metrics, see the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Key Business Metrics.”

Non-GAAP Financial Measures

In addition to our results determined in accordance with U.S. generally accepted accounting principles, or GAAP, we believe the below non-GAAP measures are useful in evaluating our operating performance. We use the below non-GAAP financial information, collectively, to evaluate our ongoing operations and for internal planning and forecasting purposes.

	Year Ended January 31,
	2017			2018			2019
	(In thousands)
Calculated Billings	$	143,390		$	289,013		$	516,972
Free Cash Flow	$	(114,038	)	$	(57,661	)	$	(97,239	)
Tender offer payments and repurchases deemed compensation(1)	8,033			39,374			—
Adjusted Free Cash Flow	$	(106,005	)	$	(18,287	)	$	(97,239	)

__________________

(1) In fiscal years 2017 and 2018, we made cash payments of $8.0 million and $39.4 million, respectively, attributable to tender offers and repurchases for our outstanding common stock, which was accounted for as compensation. Adjusted Free Cash Flow has been shown here as adjusted for these cash payments. We have adjusted our Free Cash Flow for these payments because we do not expect them to occur when we are a public company so we believe that this provides greater comparability across periods.

For additional information and reconciliations of the non-GAAP financial measures to the most directly comparable financial measures stated in accordance with GAAP, see the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Non-GAAP Financial Measures.”

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RISK FACTORS

Investing in our Class A common stock involves a high degree of risk. You should carefully consider the risks and uncertainties described below, together with all of the other information in this prospectus, before making a decision to invest in our Class A common stock. If any of the risks actually occur, our business, results of operations, financial condition, and prospects could be harmed. In that event, the trading price of our Class A common stock could decline, and you could lose part or all of your investment.

Risks Related to Our Business

We have a limited operating history, which makes it difficult to forecast our revenue and evaluate our business and future prospects.

We launched Slack publicly in 2014 and much of our growth has occurred in recent periods. As a result of our limited operating history, our ability to forecast our future results of operations and plan for and model future growth is limited and subject to a number of uncertainties. We have encountered and expect to continue to encounter risks and uncertainties frequently experienced by growing companies in rapidly evolving industries, such as the risks and uncertainties described herein. Additionally, the sales cycle for the evaluation and implementation of our paid versions, Standard and Plus, which typically ranges from a single day to multiple months, and of Enterprise Grid, which typically extends for multiple months, may also cause us to experience a delay between increasing operating expenses and the generation of corresponding revenue, if any. Accordingly, we may be unable to prepare accurate internal financial forecasts or replace anticipated revenue that we do not receive as a result of delays arising from these factors, and our results of operations in future reporting periods may be below the expectations of investors. If we do not address these risks successfully, our results of operations could differ materially from our estimates and forecasts or the expectations of investors, causing our business to suffer and our Class A common stock price to decline.

We have a history of net losses, we anticipate increasing operating expenses in the future, and we may not be able to achieve and, if achieved, maintain profitability.

We have incurred significant net losses in each year since our inception, including net losses of $146.9 million, $140.1 million, and $138.9 million in fiscal years 2017, 2018, and 2019, respectively. We expect to continue to incur net losses for the foreseeable future and we may not achieve or maintain profitability in the future. Because the market for Slack, and the features, integrations, and capabilities we offer on Slack, is rapidly evolving and has not yet reached widespread adoption, it is difficult for us to predict our future results of operations or the limits of our market opportunity. We expect our operating expenses to significantly increase over the next several years as we hire additional personnel, particularly in sales and marketing, expand our partnerships, operations, and infrastructure, both domestically and internationally, continue to enhance Slack and develop and expand its features, integrations and capabilities, and expand and improve our application programming interfaces, or APIs. We also intend to continue to build and enhance Slack through both internal research and development as well as selectively pursuing acquisitions that can uniquely contribute to Slack’s capabilities. In addition, as we grow and become a public company, we will incur additional significant legal, accounting, and other expenses that we did not incur as a private company. If our revenue does not increase to offset the expected increases in our operating expenses, we will not be profitable in future periods. In future periods, our revenue growth could slow or our revenue could decline for a number of reasons, including any failure to increase the number of organizations on Slack, increase our number of paid customers, or grow or maintain our Net Dollar Retention Rate, a decrease in the growth of our overall market, our failure, for any reason, to continue to capitalize on growth opportunities, slowing demand for Slack, additional regulatory burdens, or increasing competition. As a result, our past financial performance may not be indicative of our future performance. Any failure by us to achieve or sustain profitability on a consistent basis could cause the value of our Class A common stock to decline.

We have experienced rapid growth in recent periods and our recent growth rates may not be indicative of our future growth.

We have experienced rapid growth in recent periods. Our revenue was $105.2 million, $220.5 million, and $400.6 million for the years ended January 31, 2017, 2018, and 2019, respectively, representing annual growth of 110% and 82%, respectively. In future periods, we may not be able to sustain revenue growth consistent with recent history, or at all. Further, as we operate in a new and rapidly changing category of software, widespread acceptance and use of

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Slack is critical to our future growth and success. We believe our revenue growth depends on a number of factors, including, but not limited to, our ability to:

• attract new users and organizations;

• provide excellent customer experience;

• grow or maintain our Net Dollar Retention Rate, expand usage within organizations on Slack, and sell premium versions of Slack;

• convert users of and organizations on our free version into paid customers;

• introduce and grow adoption of Slack in new markets outside of the United States;

• expand usage of Slack between organizations through shared channels;

• achieve widespread acceptance and use of Slack;

• adequately expand our sales force;

• expand the features and capabilities of Slack, including through the creation and use of additional integrations;

• maintain the security and reliability of Slack;

• comply with existing and new applicable laws and regulations;

• price Slack effectively so that we are able to attract and retain paid customers without compromising our profitability;

• successfully compete against established companies and new market entrants, as well as existing software tools; and

• increase awareness of our brand on a global basis.

If we are unable to accomplish any of these tasks, our revenue growth will be harmed. We also expect our operating expenses to increase in future periods, and if our revenue growth does not increase to offset these anticipated increases in our operating expenses, our business, results of operations, and financial condition will be harmed, and we may not be able to achieve or maintain profitability. We have also encountered in the past, and expect to encounter in the future, risks and uncertainties frequently experienced by growing companies in rapidly evolving industries. If our assumptions regarding these risks and uncertainties, which we use to plan and operate our business, are incorrect or change, or if we do not address these risks successfully, our growth rates may slow and our business would suffer. Further, our rapid growth may make it difficult to evaluate our future prospects.

If we fail to manage our growth effectively, we may be unable to execute our business plan or maintain high levels of service and customer satisfaction.

We have experienced, and expect to continue to experience, rapid growth, which has placed, and may continue to place, significant demands on our management and our operational and financial resources. For example, our headcount has grown from 716 employees as of January 31, 2017 to 1,502 employees as of January 31, 2019. We have established international offices, including offices in Australia, Canada, Ireland, India, Japan, and the United Kingdom, and we plan to continue to expand our international operations into other countries in the future. We have also experienced significant growth in the number of users, organizations on Slack and integrations, and in the amount of data that Slack supports. Additionally, our organizational structure is becoming more complex as we scale our operational, financial and management controls as well as our reporting systems and procedures.

To manage growth in our operations and personnel, we will need to continue to grow and improve our operational, financial, and management controls and our reporting systems and procedures. We will require significant capital expenditures and the allocation of valuable management resources to grow and change in these areas without

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undermining our culture, which has been central to our growth so far. Our expansion has placed, and our expected future growth will continue to place, a significant strain on our management, customer experience, research and development, sales and marketing, administrative, financial, and other resources. If we fail to manage our anticipated growth and change in a manner that preserves the key aspects of our corporate culture, the quality of Slack may suffer, which could negatively affect our brand and reputation and harm our ability to attract users, employees, and organizations, and to grow or maintain our Net Dollar Retention Rate.

In addition, as we expand our business, it is important that we continue to maintain a high level of customer service and satisfaction. As our paid customer base continues to grow, we will need to expand our account management, customer service and other personnel, our partners, our features, and our security offerings to provide personalized account management and customer service as well as personalized features, integrations and capabilities. If we are not able to continue to provide high levels of customer service, our reputation, as well as our business, results of operations, and financial condition, could be harmed.

We may experience quarterly fluctuations in our results of operations due to a number of factors that make our future results difficult to predict and could cause our results of operations to fall below analyst or investor expectations.

Our quarterly results of operations may fluctuate from quarter to quarter as a result of a number of factors, many of which are outside of our control and may be difficult to predict, including, but not limited to:

• the level of demand for Slack;

• our ability to grow or maintain our Net Dollar Retention Rate, expand usage within organizations on Slack, and sell premium versions of Slack;

• our ability to convert users of and organizations on our free version into paid customers;

• the timing and success of new features, integrations, capabilities, and enhancements by us to Slack or by our competitors to their products or any other change in the competitive landscape of our market;

• our ability to achieve widespread acceptance and use of Slack;

• errors in our forecasting of the demand for Slack, which could lead to lower revenue, increased costs or both;

• the amount and timing of operating expenses and capital expenditures, as well as entry into operating leases, that we may incur to maintain and expand our business and operations and to remain competitive;

• the timing of expenses and recognition of revenue;

• security breaches, technical difficulties, or interruptions to Slack resulting in service level agreement credits;

• adverse litigation judgments, other dispute-related settlement payments, or other litigation-related costs;

• regulatory fines;

• changes in, and continuing uncertainty in relation to, the legislative or regulatory environment;

• legal and regulatory compliance costs in new and existing markets;

• the number of new employees added;

• the timing of the grant or vesting of equity awards to employees, directors, or consultants;

• pricing pressure as a result of competition or otherwise;

• seasonal buying patterns for IT spending;

• fluctuations in foreign currency exchange rates;

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• costs and timing of expenses related to the acquisition of businesses, talent, technologies, or intellectual property, including potentially significant amortization costs and possible write-downs; and

• general economic conditions in either domestic or international markets, including geopolitical uncertainty and instability.

Any one or more of the factors above may result in significant fluctuations in our quarterly results of operations. You should not rely on our past results as an indicator of our future performance.

The variability and unpredictability of our quarterly results of operations or other operating metrics could result in our failure to meet our expectations or those of analysts that cover us or investors with respect to revenue or other key metrics for a particular period. If we fail to meet or exceed such expectations for these or any other reasons, the market price of our Class A common stock could fall, and we could face costly lawsuits, including securities class action suits.

Real or perceived errors, failures, vulnerabilities, or bugs in Slack could harm our business, results of operations, and financial condition.

The software technology underlying and integrating with Slack is inherently complex and may contain material defects or errors, particularly when new features, integrations, or capabilities are released. Errors, failures, vulnerabilities, or bugs may occur in Slack, especially when updates are deployed or new features, integrations, or capabilities are rolled out. Slack is often used in connection with large-scale computing environments with different operating systems, system management software, integrations, equipment, and networking configurations, which may cause errors or failures, or affect other aspects of the computing environment in which Slack is used. In addition, use of Slack in complicated, large-scale computing environments may expose errors, failures, vulnerabilities, or bugs in Slack or integrations. Any such errors, failures, vulnerabilities, or bugs may not be found until after new features, integrations, or capabilities have been released to organizations on Slack. Furthermore, we will need to ensure that Slack can scale to meet the evolving needs of users and organizations on Slack, particularly as we continue to focus on larger organizations with Enterprise Grid. Real or perceived errors, failures, vulnerabilities, or bugs in Slack could result in negative publicity, loss or leaking of personal data and data of organizations on Slack, loss of or delay in market acceptance of Slack, loss of competitive position, regulatory fines or claims by organizations on Slack for losses sustained by them, all of which could harm our business, results of operations, and financial condition.

The market and software categories in which we participate are competitive, new, and rapidly changing, and if we do not compete effectively with established companies as well as new market entrants our business, results of operations, and financial condition could be harmed.

Slack is a new category of business technology in a rapidly evolving market for software, programs, and tools used by knowledge workers that is intensely competitive, fragmented, and subject to rapidly changing technology, shifting user and customer needs, new market entrants, and frequent introductions of new products and services. We also compete in various segments of the communication, collaboration, and integration software categories. Moreover, we expect competition to increase in the future from established competitors and new market entrants, including established technology companies who have not previously entered the market. Our primary competitor is currently Microsoft Corporation. Our other competitors fall into the following categories: productivity tool and email providers, such as Alphabet Inc. (including Google Inc.); unified communications providers, such as Cisco Systems Inc.; and consumer application companies who have entered the business software market, such as Facebook Inc. We also compete with smaller companies that offer niche or point products that attempt to address certain problems that Slack addresses. We further compete against existing software, programs, and tools, such as email. With the introduction of new technologies, the evolution of Slack, and new market entrants, we expect competition to intensify in the future. Established companies may not only develop their own communication and collaboration solutions, platforms for software integration, and secure repositories of information and data, but also acquire or establish product integration, distribution, or other cooperative relationships with our current competitors. For example, while we currently partner with Atlassian Corporation PLC, Google Inc., Okta, Inc., Oracle Corporation, ServiceNow, Inc., salesforce.com, inc., SAP SE, Workday, Inc., and Zoom Video Communications, Inc., among others, they may develop and introduce products that directly or indirectly compete with Slack. New competitors or alliances among competitors may emerge and rapidly acquire significant market share due to factors such as greater brand name recognition, a larger existing user and/or

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customer base, superior product offerings, a larger or more effective sales organization, and significantly greater financial, technical, marketing, and other resources and experience. We also compete with niche companies that offer specific point solutions in the communication, collaboration and data use markets, normally focused on specific industries, geographies, or specific use cases, which attempt to address certain of the problems that Slack addresses. In addition, with the recent increase in large merger and acquisition transactions in the technology industry, particularly transactions involving cloud-based technologies, there is a greater likelihood that we will compete with other large technology companies in the future. We expect this trend to continue as companies attempt to strengthen or maintain their market positions in an evolving industry. Companies resulting from these possible consolidations may create more compelling product offerings and be able to offer more attractive pricing options, making it more difficult for us to compete effectively.

Many of our existing competitors have, and some of our potential competitors could have, substantial competitive advantages such as greater brand name recognition and longer operating histories, larger sales and marketing budgets and resources, broader distribution, and established relationships with independent software vendors, partners, and customers, greater customer experience resources, greater resources to make acquisitions, lower labor, and development costs, larger and more mature intellectual property portfolios, and substantially greater financial, technical and other resources. Such competitors with greater financial and operating resources may be able to respond more quickly and effectively than we can to new or changing opportunities, technologies, standards, or customer requirements.

In addition, some of our larger competitors have substantially broader product offerings and leverage their relationships based on other products or incorporate functionality into existing products to gain business in a manner that discourages users from purchasing Slack, including through selling at zero or negative margins, product bundling, or closed technology platforms. Potential customers may also prefer to purchase from their existing suppliers rather than a new supplier regardless of product performance or features. These larger competitors often have broader product lines and market focus and will therefore not be as susceptible to downturns in a particular market. Our competitors may also seek to repurpose their existing offerings to provide software, programs, and tools used by knowledge workers with subscription models. Further, some current and potential customers, particularly large organizations, have elected, and may in the future elect, to develop or acquire their own software, programs, and tools used by knowledge workers that would reduce or eliminate the demand for Slack.

Conditions in our market could also change rapidly and significantly as a result of technological advancements, partnering by our competitors or continuing market consolidation, and it is uncertain how our market will evolve. New start-up companies that innovate and large competitors that are making significant investments in research and development may invent similar or superior products and technologies that compete with Slack. These competitive pressures in our market or our failure to compete effectively may result in price reductions, fewer customers, reduced revenue, gross profit, and gross margins, increased net losses, and loss of market share. Any failure to meet and address these factors could harm our business, results of operations, and financial condition.

If we are unable to attract new users and organizations, convert users of and organizations on our free version into paid customers, grow or maintain our Net Dollar Retention Rate, expand usage within organizations on Slack, and sell premium subscription plans or develop new features, integrations, capabilities, and enhancements that achieve market acceptance, our revenue growth and profitability will be harmed.

To increase our revenue and achieve and maintain profitability, we must add new users and organizations, convert users of and organizations on our free version into paid customers, grow or maintain our Net Dollar Retention Rate, expand usage within organizations on Slack, and sell premium subscription plans. We encourage organizations on our free version to upgrade to paid versions of Slack and paid customers of Standard to upgrade to our premium subscription plans, Plus or Enterprise Grid, through in-product prompts and notifications, by recommending additional features and by providing customer support that explains the additional capabilities of our paid and premium plans. Additionally, we seek to expand within organizations on Slack by adding new users, having organizations on our Free or Standard subscription plan upgrade to our premium plans, or expanding the use of Slack into other departments within an organization already on Slack. We often see enterprise decision-makers deciding to adopt Slack after noticing substantial organic adoption by individuals and teams within the organization. While we have experienced significant growth in the number of users on Slack, we do not know whether we will continue to achieve similar user growth rates in the future. Numerous factors, however, may impede our ability to add new users and organizations, convert users of and

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organizations on our free version into paid customers, grow and maintain our Net Dollar Retention Rate, expand usage within organizations on Slack, and sell premium subscription plans, including our inability to convert organizations using our free version into paid customers, failure to attract and effectively train new sales and marketing personnel, especially as we increase our sales efforts, failure to retain and motivate our current sales and marketing personnel, failure to develop or expand relationships with partners, failure to successfully deploy new features, integrations, and capabilities for organizations on Slack and provide quality customer experience, or failure to ensure the effectiveness of our marketing programs. Additionally, increasing our sales to large organizations requires increasingly sophisticated and costly sales efforts targeted at senior management and other personnel. If our efforts to sell to large organizations and organizations of all sizes are not successful or do not generate additional revenue, our business would suffer. See also “—Failure to effectively develop and expand our direct sales capabilities could harm our ability to increase the number of organizations on Slack and achieve broader market acceptance of Slack.”

Our ability to attract new users and organizations and increase revenue from existing paid customers depends in large part on our ability to continually enhance and improve Slack and the features, integrations, and capabilities we offer, and to introduce compelling new features, integrations, and capabilities that reflect the changing nature of our market in order to maintain and improve the quality and value of Slack, which depends on our ability to continue investing in research and development and in our ongoing efforts to improve and enhance Slack. The success of any enhancement to Slack depends on several factors, including timely completion and delivery, competitive pricing, adequate quality testing, integration with existing technologies, and overall market acceptance. Any new features, integrations, and capabilities that we develop may not be introduced in a timely or cost-effective manner, may contain errors, failures, vulnerabilities, or bugs, or may not achieve the market acceptance necessary to generate significant revenue. We must also convince developers to adopt and build on Slack. We believe that these developer-built integrations facilitate greater usage and customization of Slack and the features, integrations, and capabilities enhance user experience. If these developers stop developing on or supporting Slack, we will lose the benefits that have contributed to the growth in the number of organizations and users on Slack, and our business, results of operations, and financial condition could be harmed. If we are unable to successfully develop new features, integrations, and capabilities to enhance Slack to meet requirements of organizations on Slack, especially as we continue to grow and enhance Enterprise Grid, or otherwise gain widespread market acceptance, our business, results of operations, and financial condition would be harmed.

Moreover, our business is subscription based, and organizations are not obligated to and may not renew their subscriptions after their existing subscriptions expire. Many of our subscriptions are sold for a one-year term, though some organizations choose a month-to-month subscription plan or multi-year subscription plan. While many of our subscriptions provide for automatic renewal, organizations have no obligation to renew a subscription after the expiration of the term, and we cannot ensure that organizations will renew subscriptions with a similar contract period, with the same or greater number of users, or for the same subscription plan or upgrade to Plus or Enterprise Grid. With our fair billing practices, we may also not earn as much revenue as anticipated if the actual numbers of users in a paid customer decreases during the subscription period. Organizations may or may not renew their subscriptions as a result of a number of factors, including their satisfaction or dissatisfaction with Slack or services, our pricing or pricing structure, the pricing or capabilities of the products and services offered by our competitors, the effects of economic conditions, or reductions in our paid customers’ spending levels. In the past, few of our paid customers have elected to downgrade or not to renew agreements with us, but it is difficult to accurately predict long-term Net Dollar Retention Rates. If organizations do not renew their subscriptions, renew on less favorable terms or fail to add more users, or if we fail to upgrade organizations on our Free or Standard subscription plan to our premium subscription plans, Plus and Enterprise Grid, or expand within organizations on Slack, our revenue may decline or grow less quickly than anticipated, which would harm our business, results of operations, and financial condition.

Additionally, organizations can and do subscribe to multiple subscription plans simultaneously for a variety of reasons. For example, many of our customers are large enterprises with distributed procurement processes where different buyers, departments or affiliates make their own purchasing decisions based on distinct product features or separate budgets. Companies who are existing Slack customers may also acquire another organization that is already on a Slack subscription plan or complete a reorganization or spin-off transaction that results in an organization subscribing to multiple subscription plans. If organizations that subscribe to multiple subscription plans decide not to consolidate all of their subscription plans into an Enterprise Grid subscription for the entire organization or decide to downgrade to lower priced or free subscription plans, our revenue may decline or grow less quickly than anticipated,

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which would harm our business, results of operations, and financial condition. Having organizations on multiple subscription plans also makes it more difficult to accurately predict long-term Net Dollar Retention Rates.

Our ability to introduce new features, integrations, capabilities, and enhancements is dependent on adequate research and development resources. If we do not adequately fund our research and development efforts, or if our research and development investments do not translate into material enhancements to Slack, we may not be able to compete effectively and our business, results of operations, and financial condition may be harmed.

To remain competitive, we must continue to develop new features, integrations, capabilities, and enhancements to Slack. This is particularly true as we further expand and diversify our capabilities to address additional applications and markets. For example, in September 2017, we introduced a new beta feature, shared channels, which facilitates secure collaboration between companies. Maintaining adequate research and development resources, such as the appropriate personnel and development technology, to meet the demands of the market is essential. If we are unable to develop features, integrations, and capabilities internally due to certain constraints, such as employee turnover, lack of management ability, or a lack of other research and development resources, our business may be harmed.

Moreover, research and development projects can be technically challenging and expensive. The nature of these research and development cycles may cause us to experience delays between the time we incur expenses associated with research and development and the time we are able to offer compelling features, integrations, capabilities, and enhancements and generate revenue, if any, from such investment. Additionally, anticipated demand for a feature, integration, capability, or enhancement we are developing could decrease after the development cycle has commenced, and we would nonetheless be unable to avoid substantial costs associated with the development of any such feature, integration, capability, or enhancement. If we expend a significant amount of resources on research and development and our efforts do not lead to the successful introduction or improvement of features, integrations, and capabilities that are competitive, it would harm our business, results of operations, and financial condition.

Further, many of our competitors expend a considerably greater amount of funds on their respective research and development programs, and those that do not may be acquired by larger companies that would allocate greater resources to our competitors’ research and development programs. Our failure to maintain adequate research and development resources or to compete effectively with the research and development programs of our competitors would give an advantage to such competitors and may harm our business, results of operations, and financial condition.

If there are interruptions or performance problems associated with the technology or infrastructure used to provide Slack, organizations on Slack may experience service outages, other organizations may be reluctant to adopt Slack, and our reputation could be harmed.

Our continued growth depends, in part, on the ability of existing and potential organizations on Slack to access Slack 24 hours a day, seven days a week, without interruption or degradation of performance. We have in the past and may in the future experience disruptions, data loss, outages, and other performance problems with our infrastructure due to a variety of factors, including infrastructure changes, introductions of new functionality, human or software errors, capacity constraints, denial-of-service attacks, ransomware attacks, or other security-related incidents. In some instances, we may not be able to identify the cause or causes of these performance problems immediately or in short order. We may not be able to maintain the level of service uptime and performance required by organizations on Slack, especially during peak usage times and as our user traffic and number of integrations increase. For example, we have experienced intermittent connectivity issues and product issues in the past, including those that have prevented many organizations on Slack and their users from accessing Slack for a period of time. If Slack is unavailable or if organizations are unable to access Slack within a reasonable amount of time, or at all, our business would be harmed. Since organizations on Slack rely on Slack to communicate, collaborate, and access and complete their work, which in many cases includes entire organizations that complete substantially all of their work functions on Slack, any outage on Slack would impair the ability of organizations on Slack and their users to perform their work, which would negatively impact our brand, reputation, and customer satisfaction, and could give rise to legal liability under our service level agreements with paid customers.

Moreover, we depend on services from various third parties to maintain our infrastructure, including Amazon Web Services, or AWS. If a service provider fails to provide sufficient capacity to support Slack or otherwise experiences service outages, such failure could interrupt access to Slack by users and organizations, which could adversely affect

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their perception of Slack’s reliability and our revenue and harm the businesses of organizations on Slack. Any disruptions in these services, including as a result of actions outside of our control, would significantly impact the continued performance of Slack. In the future, these services may not be available to us on commercially reasonable terms, or at all. Any loss of the right to use any of these services could result in decreased functionality of Slack until equivalent technology is either developed by us or, if available from another provider, is identified, obtained, and integrated into our infrastructure. If we do not accurately predict our infrastructure capacity requirements, organizations on Slack could experience service shortfalls. We may also be unable to effectively address capacity constraints, upgrade our systems as needed, and continually develop our technology and network architecture to accommodate actual and anticipated changes in technology.

Any of the above circumstances or events may harm our reputation, cause organizations on Slack to terminate their agreements with us, impair our ability to obtain subscription renewals from organizations on Slack, impair our ability to grow the base of users and organizations on Slack, subject us to financial penalties and liabilities under our service level agreements with our paid customers, and otherwise harm our business, results of operations, and financial condition.

A security incident may allow unauthorized access to our systems, networks, or data or the data of organizations on Slack, harm our reputation, create additional liability, and harm our financial results.

Increasingly, companies are subject to a wide variety of attacks on their systems on an ongoing basis. In addition to threats from traditional computer “hackers,” malicious code (such as malware, viruses, worms, and ransomware), employee theft or misuse, password spraying, phishing, credential stuffing, and denial-of-service attacks, we also face threats from sophisticated organized crime, nation-state, and nation-state supported actors who engage in attacks (including advanced persistent threat intrusions) that add to the risks to Slack, our internal systems and our partners’ systems, as well as the systems of organizations on Slack and the information that they store and process. Third parties may attempt to fraudulently induce employees, users, or organizations into disclosing sensitive information such as user names, passwords, or other information or otherwise compromise the security of our internal electronic systems, networks, and/or physical facilities in order to gain access to our data or the data of organizations on Slack, which could result in significant legal and financial exposure, a loss of confidence in the security of Slack, interruptions or malfunctions in our operations, and, ultimately, harm to our future business prospects and revenue. Users or organizations on Slack may also disclose or lose control of their API keys, secrets, or passwords, or use the same or similar secrets or passwords on third parties’ systems, which could lead to unauthorized access to their accounts and data within Slack (arising from, for example, an independent third-party data security incident that compromises those API keys, secrets, or passwords). Further, if a channel is shared between paid customers or workspaces, the above risks, vulnerabilities, and threats may be “inherited” or transferred from one paid customer or workspace to another. Despite significant efforts to create security barriers to such threats, it is virtually impossible for us to entirely mitigate these risks, especially where they are attributable to the behavior of independent third parties beyond our control. The security measures we have implemented or integrated into Slack and our internal systems and networks (including measures to audit third-party and custom applications), which are designed to detect unauthorized activity and prevent or minimize security breaches, may not function as expected or may not be sufficient to protect Slack and our internal systems and networks against certain attacks. For instance, for a period of approximately four days in March 2015, a security incident occurred in which unauthorized third parties had access to information maintained by us that included user names, email addresses, encrypted passwords, and information that users may have optionally added to their profiles, such as phone numbers. We are not aware of any material impact on any organizations that resulted from the incident. In addition, techniques used to sabotage or to obtain unauthorized access to systems and networks in which data is stored or through which data is transmitted change frequently and generally are not recognized until launched against a target. As a result, it may not be possible for us to anticipate these techniques or implement adequate preventative measures to prevent an electronic intrusion into our systems and networks and we may be required to expend significant capital and financial resources to protect against such threats or to alleviate problems caused by breaches in systems, network, or data security. Our board of directors has primary responsibility for overseeing cybersecurity risk management. For more information, see “Management—Role of Board of Directors in Risk Oversight.”

The storage, transmittal, and use of data by organizations on Slack concerning, among others, their employees, contractors, customers, and partners is essential to their use of Slack, which stores, transmits, and processes their sensitive and proprietary information, including business strategies, financial and operational data, personal or

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identifying information, and other related data. Security breaches impacting Slack or integrations on Slack could result in a risk of loss, unavailability, or unauthorized disclosure of this information, which, in turn, could lead to litigation, governmental audits, and investigations and possible liability (including regulatory fines), damage our relationships with existing users and organizations on Slack, and have a negative impact on our ability to attract new users and organizations and to grow or maintain our Net Dollar Retention Rate. Furthermore, any such breach, including a breach of the systems or networks of our partners or organizations on Slack, could compromise our systems or networks, creating system disruptions or slowdowns and exploiting security vulnerabilities of our networks or the networks of our partners and organizations on Slack, and the information stored on our network or the networks of our partners and organizations on Slack could be accessed, publicly disclosed, altered, lost, or stolen, which could subject us to liability and cause us financial harm. In addition, a breach of the security measures of one of our partners could result in the destruction, modification, or exfiltration of confidential corporate information, or other data that may provide additional avenues of attack. These breaches, or any perceived breach, of our systems or networks or the systems of our partners or organizations on Slack, whether or not any such breach is due to a vulnerability in Slack, may also undermine confidence in Slack or our industry and result in damage to our reputation, negative publicity, loss of users, organizations on Slack, partners, and sales, increased costs to remedy any problem, and costly litigation or regulatory fines.

We maintain errors, omissions, and cyber liability insurance policies covering certain security and privacy damages. However, we cannot be certain that our coverage will be available or adequate for all liabilities that might actually be incurred or that insurance will continue to be available to us on economically reasonable terms, or at all. Further, if a high-profile security breach occurs with respect to another software company with communication, collaboration, data collection, and integrations, our users and potential users could lose trust in the security of such solutions providers generally, which could adversely impact our ability to attract organizations to Slack or grow or maintain our Net Dollar Retention Rate.

Any actual or perceived failure by us to comply with privacy, data protection, information security, consumer privacy, data residency, or telecommunications laws, regulations, government access requests, and obligations in one or multiple jurisdictions could result in proceedings, actions, or penalties against us and could harm our business and reputation. These laws are uncertain, evolving, and interpreted and applied in different ways in different countries and, as a result, our legal obligations in different countries, and our efforts to comply with those legal obligations, may be inadequate or in conflict.

The use and storage of data, files, and information by organizations on Slack concerning, among others, their employees, contractors, customers, and partners is essential to their use of Slack. We have implemented various features, integrations, and capabilities as well as contractual obligations intended to enable and encourage organizations on Slack to comply with applicable privacy and security requirements in their collection, use, and transmittal of data using Slack, but these features do not ensure their compliance and may not be effective against all potential privacy concerns. In addition, we are subject to certain contractual obligations regarding the collection, use, storage, transfer, disclosure, and/or processing of personal data.

Around the world, there are numerous lawsuits and regulatory proceedings in process against various technology companies that process personal data. If those lawsuits or regulatory proceedings are successful, it could increase the likelihood that we may be exposed to liability for our own policies and practices concerning the processing of personal data and could hurt our business. Privacy, security, or data protection concerns, whether or not valid, may inhibit market adoption of Slack. For instance, Slack currently only utilizes AWS data centers located in the United States but certain organizations, or categories of organizations, may limit their adoption or use of Slack unless we also utilize local AWS data centers, such as data centers in Europe, Asia, and Latin America. Additionally, concerns about privacy, security, or data protection may result in the adoption of new legislation that restricts the implementation of technologies like ours or requires us to make modifications to Slack, which could significantly limit the adoption and deployment of our technologies or result in significant expense to us. Many jurisdictions have enacted or are considering enacting privacy and/or data security legislation, including laws and regulations applying to the collection, use, storage, transfer, disclosure, and/or processing of personal data. Such laws may include data residency or data localization requirements, which generally require that certain types of data collected within a certain country be stored and processed within that country and/or data export restrictions, or international transfer laws which prohibit or impose conditions upon the transfer of such data from one country to another. In addition, some jurisdictions have recently enacted or are currently considering enacting laws requiring online service providers to be able to decrypt encrypted content stored as part of

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their service, which may limit deployment and adoption of Slack. The costs of compliance with, and other burdens imposed by, such laws and regulations that are applicable to the operations of organizations on Slack may limit the use and adoption of Slack and reduce overall demand for Slack. Moreover, the existence and need to comply with such privacy and data security laws could impact our ability to offer Slack in certain markets without taking additional compliance steps (including the use of local data centers) or in general. Further, these privacy and data security related laws and regulations are evolving and may result in increasing regulatory and public scrutiny and escalating levels of enforcement and sanctions and impose regulatory challenges on our business. For instance, evolving and changing definitions of what constitutes “Personal Information” and “Personal Data” within the European Union, the United States, and elsewhere, especially relating to classification of IP addresses, machine, or device identification numbers, location data, and other information, may limit or inhibit our ability to operate or expand our business.

Although we continually work to comply with federal, state, and foreign laws and regulations, industry standards, contractual obligations, and other legal obligations that apply to us, such laws, regulations, standards, and obligations are evolving and may be modified, interpreted, and applied in an inconsistent manner from one jurisdiction to another, and may conflict with one another, other requirements or legal obligations, our practices, or the features of Slack. In particular, as a U.S. company we may be obliged to disclose data pursuant to governmental requests under U.S. law. This requirement may make our platform less attractive to users and organizations. Further, compliance with such U.S. governmental requests may be inconsistent with local laws in other countries to which we and organizations on Slack are subject.

Any failure or perceived failure by us to comply with federal, state, or foreign laws or regulations, industry standards, Internet accessibility standards, contractual obligations, or other legal obligations, or any actual or suspected security incident, whether or not resulting in unauthorized access to, or acquisition, release, or transfer of personal or other data, may result in governmental enforcement actions and prosecutions, private litigation, fines, and penalties, or adverse publicity and could cause organizations on Slack to lose trust in us, which could have an adverse effect on our reputation and business. For example, fines of up to the greater of €20.0 million and 4% of our global turnover can be imposed for breaches of the E.U.’s General Data Protection Regulation. Any inability to adequately address privacy and security concerns, even if unfounded, or comply with applicable laws, regulations, policies, industry standards, contractual obligations, or other legal obligations could result in additional cost and liability to us, damage our reputation, inhibit sales, and adversely affect our business.

We also expect that there will continue to be new proposed laws, regulations, Internet accessibility standards, and industry standards concerning privacy, data protection, and information security in the United States, the European Union, and other jurisdictions, and we cannot yet determine the impact such future laws, regulations, and standards may have on our business. For example, in June 2018 the State of California enacted the California Consumer Privacy Act, which takes effect on January 1, 2020 and will broadly define personal information, give California residents expanded privacy rights and protections and provide for civil penalties for violations and a private right of action for data breaches. In addition to government activity, privacy advocacy groups, and technology and other industries are considering various new, additional, or different self-regulatory standards that may place additional burdens on us. Future laws, regulations, standards, and other obligations, and changes in the interpretation of existing laws, regulations, standards, and other obligations could impair the ability of us or organizations on Slack to collect, use, or disclose information relating to consumers, which could decrease demand for Slack, increase our operating expenses, and impair our ability to maintain and grow the base of users and organizations on Slack and our revenue. Similarly, such laws could require changes to our technology, operations, and practices. New laws, amendments to, or re-interpretations of existing laws and regulations, industry standards, contractual obligations, and other obligations may require us to incur additional costs and restrict our business operations. Such laws and regulations may require companies to implement privacy and security policies, permit users to access, correct, and delete personal data stored or maintained by such companies, inform individuals of security breaches that affect their personal information, and, in some cases, obtain individuals’ consent to use personal data for certain purposes. If we, or the third parties on which we rely, fail to comply with federal, state, and foreign data privacy laws and regulations, our ability to successfully operate our business and pursue our business goals could be harmed.

Failure by us to comply with applicable laws and regulations, or to protect such data, could result in enforcement actions against us, including fines and public censure, claims for damages by organizations on Slack and other affected

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persons, damage to our reputation, and loss of goodwill (both in relation to existing and prospective organization on Slack), any of which could harm our business, results of operations, and financial condition.

Since many of the features of Slack involve the processing of personal data or other data of organizations on Slack and their employees, contractors, customers, partners, and others, any inability to adequately address privacy concerns, even if such concerns are unfounded, or to comply with applicable privacy or data security laws, regulations, and policies, could result in liability to us, damage to our reputation, inhibition of sales and to our business. Addressing these concerns could increase the length of our sales cycles. For example, cultural norms around privacy and employee expectations vary country to country and can drive a need to localize or customize certain features of Slack in order to address such varied privacy concerns, which can add cost and time to our development and sales cycles. In some markets, such as Germany, organizations as well as their employees through works councils, must both determine whether Slack is adopted, and organization and employee expectations around privacy do not always align. As a result, concerns by employees with respect to the protection of their privacy rights could affect adoption of Slack.

We publicly post our privacy policies and practices concerning our processing, use and disclosure of the personal data provided to us by users, organizations, and website visitors. Our publication of our privacy policies and other statements we publish that provide promises and assurances about privacy and security can subject us to potential state and federal action, as well as enforcement action in other countries (particularly the European Union) if they are found to omit necessary information, be deceptive, or misrepresentative of our practices. If Slack is perceived to cause, or is otherwise unfavorably associated with, violations of privacy or data security requirements, it may subject us or organizations on Slack to public criticism and potential legal liability. Existing and potential privacy laws and regulations concerning privacy and data security and increasing sensitivity of consumers to unauthorized processing of personal data may create negative public reactions to technologies and products such as ours. This, in turn, may reduce the value of Slack and slow or eliminate the growth of our business.

We may face particular privacy, data security, and data protection risks in Europe particularly due to the new European General Data Protection Regulation.

In relation to transfers of Personal Data out of the European Economic Area, or the EEA, and Switzerland to the United States, we are currently registered for both the E.U.-U.S. and the Swiss-U.S. Privacy Shield programs. There are concerns about the future of Privacy Shield as a data transfer mechanism as it continues to be subject to legal challenges, which, if successful, would require us to ensure that we had alternative data transfer mechanisms. In the interim, if we are investigated by a European data protection authority or the U.S. Federal Trade Commission, or the FTC, and found to have failed to comply with the Privacy Shield programs, we may face fines and other penalties. Any such investigation or charges by European and/or Swiss data protection authorities and/or the FTC could have a negative effect on our existing business and on our ability to attract new users and organizations and to grow or maintain our Net Dollar Retention Rate.

We also use model contractual clauses (or standard contractual clauses) to transfer, and to enable organizations on Slack to transfer, personal data out of Europe. The validity of model clauses is also the subject of litigation. If the E.U.-U.S. Privacy Shield program or the European Commission decisions underpinning the model contractual clauses are invalidated, we will be required to identify and implement other methods to enable compliant data transfers from the EEA and Switzerland to the United States. Such methods may be more costly or not available to us.

Depending on the evolving legal framework, we may find it necessary to establish systems to maintain Personal Data originating from the European Union in the EEA, which may involve substantial expense and may cause us to need to divert resources from other aspects of our business, all of which may adversely affect our business.

In addition, data protection regulation is an area of increased focus and changing requirements. The European Union adopted the General Data Protection Regulation 2016/679, or GDPR, that took effect on May 25, 2018, largely replacing the current data protection laws of each E.U. member state. The GDPR applies to any organization with an establishment in the European Union for data processing purposes as well as to those outside the European Union if they process Personal Data of individuals in the European Union in connection with offering them goods or services or monitoring their behavior. The GDPR enhances data protection obligations for processors and controllers of Personal Data, including, for example, expanded disclosures about how Personal Data is to be used, limitations on retention of information, mandatory data breach notification requirements, and additional obligations on service providers (such

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as any third parties to whom we may transfer Personal Data). Non-compliance with the GDPR can trigger fines of up to the greater of €20 million and 4% of our global revenue. Given the breadth and depth of changes in data protection obligations, compliance has caused us to expend significant resources, and such expenditures are likely to continue into the future as we continue our compliance efforts and respond to new interpretations and enforcement actions. In addition, separate E.U. laws and regulations (and member states’ implementations thereof) govern the protection of consumers and of electronic communications and these are also evolving. A draft of the new ePrivacy Regulation extends the strict opt-in marketing rules with limited exceptions to business-to-business communications, alters rules on third-party cookies, web beacons, and similar technology and significantly increases penalties. This law, as well as related changes to the European Union’s telecommunications regime, could subject us to additional privacy obligations of the sort that have historically been imposed primarily on telecommunication service providers. We cannot yet determine the impact that such future laws, regulations, and standards may have on our business. Such laws and regulations are often subject to differing interpretations and may be inconsistent among jurisdictions. Further, the obligations imposed by E.U. data protection and related laws may conflict with the obligations imposed by other legal regimes, such as U.S. laws concerning government access to data. We may incur substantial expense in complying with the new obligations to be imposed by the GDPR, and we may be required to make significant changes in our business operations and product development, all of which may adversely affect our revenues and our business overall.

If we are unable to ensure that Slack interoperates with a variety of software applications that are developed by others, including our partners, Slack may become less competitive and our results of operations may be harmed.

Slack must integrate with a variety of network, hardware, and software platforms, and we need to continuously modify and enhance Slack to adapt to changes in hardware, software, networking, browser, and database technologies. In particular, we have developed Slack to be able to easily integrate with third-party applications, including the applications of software providers that compete with us as well as our partners, through the interaction of APIs. In general, we rely on the providers of such software systems to allow us access to their APIs to enable these user integrations. We are typically subject to standard terms and conditions for application developers of such providers, which govern the distribution, operation, and fees of such software systems, and which are subject to change by such providers from time to time. Our business may be harmed if any provider of such software systems:

• discontinues or limits our access to its software or APIs;

• modifies its terms of service or other policies, including fees charged to, or other restrictions on us or other application developers;

• changes how information is accessed by us, our users, or organizations on Slack;

• establishes more favorable relationships with one or more of our competitors; or

• develops or otherwise favors its own competitive offerings over ours.

We believe a significant component of our value proposition to users and organizations is the ability to improve and interface with these third-party applications through APIs on and directly in Slack. Third-party services and products are constantly evolving, and we may not be able to modify Slack to assure its compatibility with that of other third parties following development changes. In addition, some of our competitors may be able to disrupt the operations or compatibility of Slack with their products or services, or exert strong business influence on our ability to, and terms on which we, operate Slack. For example, we currently directly compete with several large technology companies whose applications interface with Slack, including Google and Microsoft. As our respective products evolve, we expect this level of competition to increase. Should any of our competitors modify their products or standards in a manner that degrades the functionality of Slack or gives preferential treatment to competitive products or services, whether to enhance their competitive position or for any other reason, the interoperability of Slack with these products could decrease and our business, results of operations, and financial condition could be harmed. If we are not permitted or able to integrate with these and other third-party applications in the future, demand for Slack would be harmed and our business, results of operations, and financial condition would be harmed.

We also depend on our ecosystem of developers to create applications that will integrate with Slack. Our reliance on this ecosystem of developers creates certain business risks relating to the quality and security of the applications

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built using our APIs, service interruptions of Slack from these applications, lack of service support for these applications, possession of intellectual property rights associated with these applications, and privacy concerns around the transfer of data to these applications. We may not have the ability to control or prevent these risks. As a result, issues relating to these applications could adversely affect our business, brand, and reputation.

Further, we have created mobile applications and mobile versions of Slack to respond to the increasing number of people who access the Internet through mobile devices and access cloud-based software applications through mobile devices, including smartphones and handheld tablets or laptop computers. If these mobile applications do not perform well, our business may suffer. We are also dependent on third-party application stores that may prevent us from timely updating Slack; building new features, integrations, and capabilities; or charging for access. We distribute the mobile Slack application via smartphone and tablet application stores managed by Apple and Google, among others. Certain of these companies are now, and others may in the future become, competitors of ours, and could stop allowing or supporting access to Slack through their products, could allow access for us only at an unsustainable cost, or could make changes to the terms of access in order to make Slack less desirable or harder to access, for competitive reasons. In addition, Slack interoperates with servers, mobile devices, and software applications predominantly through the use of protocols, many of which are created and maintained by third parties. We, therefore, depend on the interoperability of Slack with such third-party services, mobile devices, and mobile operating systems, as well as cloud-enabled hardware, software, networking, browsers, database technologies, and protocols that we do not control. Any changes in such technologies that degrade the functionality of Slack or give preferential treatment to competitive services could adversely affect adoption and usage of Slack. Also, we may not be successful in developing or maintaining relationships with key participants in the mobile industry or in ensuring that Slack operates effectively with a range of operating systems, networks, devices, browsers, protocols, and standards. If we are unable to effectively anticipate and manage these risks, or if it is difficult for users and organizations on Slack to access and use Slack, our business, results of operations, and financial condition may be harmed.

Because we recognize subscription revenue over the subscription term, downturns or upturns in new sales and renewals are not immediately reflected in full in our results of operations.

We recognize revenue from subscriptions to Slack on a straight-line basis over the term of the contract subscription period beginning on the date access to Slack is granted, provided all other revenue recognition criteria have been met. Our subscription arrangements generally have monthly or annual contractual terms. As a result, much of the revenue we report each quarter is the recognition of deferred revenue from recurring subscriptions and related support services contracts entered into during previous quarters. Consequently, a decline in new or renewed recurring subscription contracts in any one quarter will not be fully reflected in revenue in that quarter, but will negatively affect our revenue in future quarters. Accordingly, the effect of significant downturns in new or renewed sales of our recurring subscriptions are not reflected in full in our results of operations until future periods. By contrast, a significant majority of our costs are expensed as incurred, which occurs as soon as a user starts using Slack. As a result, an increase in paid customers could result in our recognition of more costs than revenue in the earlier portion of the subscription term, and we may not attain profitability in any given period.

Our financial results may fluctuate due to increasing variability in our sales cycles as a substantial portion of our sales efforts are targeted at large organizations.

We plan our expenses based on certain assumptions about the length and variability of our sales cycle. These assumptions are based upon historical trends for sales cycles and conversion rates associated with organizations on Slack, which may not be indicative of future trends or results. As we continue to expand our efforts on sales to larger organizations, we expect our average sales cycles to lengthen and become less predictable, which may harm or cause unpredictable fluctuations in our financial results. Factors that may influence the length and variability of our sales cycle include, among other things:

• the need to raise awareness about the uses and benefits of Slack, particularly our paid versions;

• the need to allay privacy and security concerns or develop required enhancements;

• the discretionary nature of purchasing and budget cycles and decisions;

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• the competitive nature of evaluation and purchasing processes;

• announcements or planned introductions of new features, integrations, and capabilities by us or our competitors; and

• often lengthy purchasing approval processes.

Our increasing focus on sales to larger organizations may further increase the variability of our financial results. To achieve acceptance of Slack by additional large organizations, we may need to engage with senior management and other personnel and not just gain acceptance of Slack from employees, who are often the initial adopters of Slack. As a result, sales efforts targeted at large organizations involve greater costs, longer sales cycles, greater competition, and less predictability in completing some of our sales. In the large organization market, an organization’s decision to use Slack, expand the use of Slack, and/or upgrade to a paid version of Slack can sometimes be an enterprise-wide decision, in which case, we typically provide designated account and customer success teams, greater levels of user and customer education to familiarize potential users and organizations with the use and benefits of Slack, as well as the design and implementation of special enterprise-specific integrations. In addition, larger organizations may demand more customization, integration, support services, and features. As a result of these factors, these sales opportunities may require us to devote greater sales support, research and development, customer experience, and professional services resources to these organizations, resulting in increased costs, lengthened sales cycle, and diversion of our own sales and professional services resources to a smaller number of larger organizations. Further, we have limited experience in selling and marketing to larger organizations, and we may not be able to successfully execute our sales and marketing strategy targeted at such large organizations. Moreover, these larger transactions may require us to delay revenue recognition on some of these transactions until the technical or implementation requirements have been met. If we are unable to close one or more expected significant transactions with large organizations in a particular period, or if an expected transaction is delayed until a subsequent period, our results of operations for that period, and for any future periods in which revenue from such transaction would otherwise have been recognized, may be harmed.

If we fail to adapt to rapid technological change, our ability to remain competitive could be impaired.

The industry in which we compete is characterized by rapid technological change, frequent introductions of new products and features, and evolving industry standards and regulatory requirements. Our ability to attract new users and organizations and increase revenue from organizations on Slack will depend in significant part on our ability to anticipate industry standards and trends and continue to enhance Slack and introduce new features, integrations, and capabilities on a timely basis to keep pace with technological developments. If we are unable to provide enhancements and new features and integrations for Slack, develop new features, integrations, and capabilities that achieve market acceptance, or innovate quickly enough to keep pace with rapid technological developments, our business could be harmed. We must also keep pace with changing legal and regulatory regimes that affect Slack and our business practices. We may not be successful in developing modifications, enhancements, and improvements; in bringing them to market quickly or cost-effectively in response to market demands; or at modifying Slack to remain compliant with applicable legal and regulatory requirements.

If we fail to offer high-quality customer experience, our business and reputation will suffer.

While we have designed Slack to be easy to adopt and use, once organizations and their users begin using Slack, those organizations rely on our support services to resolve any related issues. High-quality user and customer education and customer experience has been key to our brand and is important for the successful marketing and sale of Slack, for the conversion of organizations on our free version into paid customers, and for growth or maintenance of our Net Dollar Retention Rate. The importance of high-quality customer experience will increase as we expand our business and pursue new organizations. For instance, if we do not help organizations on Slack quickly resolve issues and provide effective ongoing customer experience at the individual user and organization levels, our ability to sell our paid versions to organizations on our free version would suffer and our reputation with existing or potential users and organizations may be harmed. Further, our sales are highly dependent on our business reputation and on positive recommendations from existing users and organizations on Slack. Any failure to maintain high-quality customer experience, or a market perception that we do not maintain high-quality customer experience, could harm our reputation, our ability to sell Slack to existing and prospective organizations, and our business, results of operations, and financial condition.

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In addition, as we continue to grow our operations and reach a larger and increasingly global customer and user base, we need to be able to provide efficient customer support that meets the needs of organizations on Slack globally at scale. The number of organizations on Slack has grown significantly and that will put additional pressure on our support organization. In order to meet these needs, we have relied in the past, and will continue to rely on, third-party contractors and self-service product support to resolve common or frequently asked questions, which supplement our customer experience teams. If we are unable to provide efficient product support globally at scale, including through the use of third-party contractors and self-service support, our ability to grow our operations may be harmed and we may need to hire additional support personnel, which could harm our results of operations.

Failure to effectively develop and expand our direct sales capabilities could harm our ability to increase the number of organizations on Slack and achieve broader market acceptance of Slack.

Our ability to increase the number of organizations on Slack, grow usage within larger organizations on Slack, and achieve broader market acceptance of Slack among large organizations will depend to a significant extent on our ability to expand our sales operations, particularly our direct sales efforts targeted at C-suite executives and business unit leaders. We plan to continue expanding our direct sales force, both domestically and internationally, in order to reach these large organizations. This expansion will require us to invest significant financial and other resources to train and grow our direct sales force, in order to complement our self-service go-to-market approach. Our business will be harmed if our efforts do not generate a corresponding increase in revenue. We may not achieve anticipated revenue growth from expanding our direct sales force if we are unable to hire and develop talented direct sales personnel, if our new direct sales personnel are unable to achieve desired productivity levels in a reasonable period of time or if we are unable to retain our existing direct sales personnel. We believe that there is significant competition for sales personnel with the skills and technical knowledge that we require. Our ability to achieve revenue growth will depend, in large part, on our success in recruiting, training, and retaining sufficient numbers of sales personnel to support our growth.

Certain estimates of market opportunity included in this prospectus may prove to be inaccurate.

This prospectus includes our internal estimates of the addressable market for Slack. Market opportunity estimates, whether obtained from third-party sources or developed internally, are subject to significant uncertainty and are based on assumptions and estimates that may not prove to be accurate. The estimates and forecasts in this prospectus relating to the size of our target market, market demand and adoption, capacity to address this demand, and pricing may prove to be inaccurate. The addressable market we estimate may not materialize for many years, if ever, and even if the markets in which we compete meet the size estimates in this prospectus, our business could fail to grow at similar rates, if at all.

Adverse general economic and market conditions and reductions in IT spending may reduce demand for Slack, which could harm our revenue, results of operations, and cash flows.

Our revenue, results of operations, and cash flows depend on the overall demand for and use of Slack. Concerns about the systemic impact of a recession (in the United States or globally), energy costs, geopolitical issues, or the availability and cost of credit could lead to increased market volatility, decreased consumer confidence, and diminished growth expectations in the U.S. economy and abroad, which in turn could result in reductions in IT spending by existing and prospective organizations. Prolonged economic slowdowns may result in organizations on Slack requesting us to renegotiate existing contracts on less advantageous terms to us than those currently in place or defaulting on payments due on existing contracts or not renewing at the end of the contract term.

Organizations on Slack may merge with other entities who use alternative software that addresses one or more of the problems that Slack solves and, during weak economic times, there is an increased risk that one or more of our paid customers will file for bankruptcy protection, either of which may harm our revenue, profitability, and results of operations. We also face risk from international paid customers that file for bankruptcy protection in foreign jurisdictions, particularly given that the application of foreign bankruptcy laws may be more difficult to predict. In addition, we may determine that the cost of pursuing any claim may outweigh the recovery potential of such claim. As a result, broadening or protracted extension of an economic downturn could harm our business, revenue, results of operations, cash flows, and financial condition.

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If we fail to maintain our brand cost-effectively, our ability to expand the number of organizations on Slack will be impaired, our reputation may be harmed, and our business, results of operations, and financial condition may suffer.

We believe that developing and maintaining awareness of our brand is critical to achieving widespread acceptance of Slack and is an important element in attracting new organizations to Slack. Furthermore, we believe that the importance of brand recognition will increase as competition in our market increases. Successful promotion of our brand will depend largely on the effectiveness of our marketing efforts and on our ability to ensure that Slack remains high-quality, reliable, and useful at competitive prices.

Brand promotion activities may not yield increased revenue, and even if they do, any increased revenue may not offset the expenses we incur in building our brand. If we fail to successfully promote and maintain our brand, or incur substantial expenses in an unsuccessful attempt to promote and maintain our brand, we may fail to attract new organizations to Slack or to grow or maintain our Net Dollar Retention Rate to the extent necessary to realize a sufficient return on our brand-building efforts, and our business, results of operations, and financial condition could suffer. In January 2019, we launched our new brand campaign. Such rebranding may not be as successful as our current brand and may not achieve its intended results. Furthermore, in connection with the development and implementation of our rebranding campaign, we have spent, and continue to expect to spend, additional time and costs, including those associated with advertising and marketing efforts. If we are unable to effectively implement our rebranding campaign, our business, results of operations, and financial condition could suffer.

In addition, independent industry analysts often provide reviews of Slack, as well as the products offered by our competitors, and perception of the relative value of Slack in the marketplace may be significantly influenced by these reviews. If these reviews are negative, or less positive as compared to those of our competitors’ products, our brand may be harmed.

One of our marketing strategies is to offer a free version of Slack, and we may not be able to realize the benefits of this strategy.

We offer a free version of Slack to promote initial usage, brand and product awareness, and organic adoption. Historically, not all users of and organizations on our free version convert to one of our paid versions. Our marketing strategy depends in part on users of and/or organizations on the free version of Slack convincing others within their organizations to use Slack and to drive the conversion to purchasing subscriptions to Standard, Plus, or Enterprise Grid. To the extent that some of these users and organizations do not become, or lead others to become, paid customers, we will not realize the intended benefits of this marketing strategy, which incurs costs as we must pay to host our free version, and our ability to grow our business may be harmed and our results of operations and financial condition could suffer.

We derive, and expect to continue to derive, substantially all of our revenue from a single product.

We derive, and expect to continue to derive, substantially all of our revenue from a single product – Slack. As such, the continued growth in market demand for and market acceptance of Slack is critical to our continued success. Demand for Slack is affected by a number of factors, many of which are beyond our control, such as continued market acceptance, the timing of development, and release of competing new products; the development and acceptance of new features, integrations, and capabilities; price or product changes by us or our competitors; technological changes and developments within the markets we serve; growth, contraction, and rapid evolution of our market; and general economic conditions and trends. If we are unable to continue to meet demands of organizations on Slack or trends in preferences or to achieve more widespread market acceptance of Slack, our business, results of operations, and financial condition could be harmed. Changes in preferences of users or organizations on Slack for software may have a disproportionately greater impact on us than if we offered multiple products. In addition, some current and potential organizations, particularly large organizations, may develop or acquire their own tools or software or continue to rely on traditional tools and software, such as email, which would reduce or eliminate the demand for Slack. If demand for Slack declines for any of these or other reasons, our business could be adversely affected.

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Our corporate culture has contributed to our success, and if we cannot maintain this culture as we grow, we could lose the innovative approach, creativity, and teamwork fostered by our culture and our business could be harmed.

We believe that an important contributor to our success has been our corporate culture, which we believe creates an environment that drives and perpetuates our strategy to create a better, more productive way to work. As we continue to grow, including geographically, and develop the infrastructure of a public company, we may find it difficult to maintain our corporate culture. Any failure to preserve our culture could harm our future success, including our ability to retain and recruit personnel, innovate and operate effectively, and execute on our business strategy.

Interruptions or delays in the services provided by third-party data centers or Internet service providers could impair Slack and our business could suffer.

We currently serve organizations on Slack from third-party data centers operated by AWS. Any damage to or failure of our systems generally would prevent us from operating our business. We rely on the Internet and, accordingly, depend upon the continuous, reliable, and secure operation of Internet servers, related hardware and software, and network infrastructure. We host Slack using AWS data centers, a provider of cloud infrastructure services. Our operations depend on protecting the virtual cloud infrastructure hosted in AWS by maintaining its configuration, architecture, and interconnection specifications, as well as the information stored in these virtual data centers and which third-party Internet service providers transmit. Furthermore, we have no physical access or control over the services provided by AWS. Although we have disaster recovery plans that utilize multiple AWS locations, the data centers that we use are vulnerable to damage or interruption from human error, intentional bad acts, earthquakes, floods, fires, severe storms, war, terrorist attacks, power losses, hardware failures, systems failures, telecommunications failures, and similar events, many of which are beyond our control, any of which could disrupt our service, destroy user content, or prevent us from being able to continuously back up or record changes in our users’ content. In the event of significant physical damage to one of these data centers, it may take a significant period of time to achieve full resumption of our services, and our disaster recovery planning may not account for all eventualities. Further, a prolonged AWS service disruption affecting Slack for any of the foregoing reasons could damage our reputation with current and potential organizations, expose us to liability, cause us to lose organizations on Slack, or otherwise harm our business. We may also incur significant costs for using alternative equipment or taking other actions in preparation for, or in reaction to, events that damage the AWS services we use. Damage or interruptions to these data centers could harm our business. Moreover, negative publicity arising from these types of disruptions could damage our reputation and may adversely impact use of Slack. We may not carry sufficient business interruption insurance to compensate us for losses that may occur as a result of any events that cause interruptions in our service. Further, the contractual commitments that we provide to organizations on Slack with regard to data privacy are limited by the commitments that AWS has provided us.

AWS enables us to order and reserve server capacity in varying amounts and sizes distributed across multiple regions. AWS provides us with computing and storage capacity pursuant to an agreement that continues until terminated by either party. In some cases, AWS may terminate the agreement for cause upon 30 days’ notice. Termination of the AWS agreement may harm our ability to access data centers we need to host Slack or to do so on terms as favorable as those we have with AWS.

Slack is accessed by a large number of organizations and users, and as we continue to expand the number of users and organizations on Slack and integrations available to organizations on Slack, we may not be able to scale our technology to accommodate the increased capacity requirements, which may result in interruptions or delays in service. In addition, the failure of AWS data centers or third-party Internet service providers to meet our capacity requirements could result in interruptions or delays in access to Slack or impede our ability to scale our operations. In the event that our AWS service agreements are terminated, or there is a lapse of service, interruption of Internet service provider connectivity or damage to such facilities, we could experience interruptions in access to Slack as well as delays and additional expense in arranging new facilities and services.

Our growth depends, in part, on the success of our strategic relationships with third parties.

To grow our business and build out our application ecosystem, we anticipate that we will continue to depend on relationships with third parties. Identifying partners, and negotiating and documenting relationships with them, requires significant time and resources. Further, our competitors may be effective in providing incentives to third parties to favor their products or services over Slack. If we are unsuccessful in establishing or maintaining our relationships with third

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parties, if any existing or future partners fail to successfully implement or support Slack integrations, or if they partner with our competitors and devote greater resources to implement and support the products and solutions of competitors, our ability to compete in the marketplace, or to grow our revenue, could be impaired, and our results of operations may suffer. Even if we are successful, we cannot assure you that these relationships will result in increased usage of Slack or increased revenue.

We rely on software and services from other parties. Defects in, or the loss of access to, software or services from third parties could increase our costs and adversely affect the quality of Slack.

We rely on technologies from third parties to operate critical functions of our business, including cloud infrastructure services provided by AWS and customer relationship management services. Our business would be disrupted if any of the third-party software or services we utilize, or functional equivalents thereof, were unavailable due to extended outages or interruptions or because they are no longer available on commercially reasonable terms or prices. In each case, we would be required to either seek licenses to software or services from other parties and redesign Slack or certain aspects of Slack to function with such software or services or develop these components ourselves, which would result in increased costs and could result in delays in launches and releases of new features, integrations, capabilities or enhancements until equivalent technology can be identified, licensed, or developed, and integrated into Slack. Furthermore, we might be forced to limit the features available in Slack. These delays and feature limitations, if they occur, could harm our business, results of operations, and financial condition.

If we fail to adequately protect our proprietary rights, our competitive position could be impaired and we may lose valuable assets, generate reduced revenue, and incur costly litigation to protect our rights.

Our success is dependent, in part, upon protecting our proprietary information and technology. We rely on a combination of patents, copyrights, trademarks, service marks, trade secret laws, and contractual restrictions to establish and protect our proprietary rights. However, the steps we take to protect our intellectual property may be inadequate. We will not be able to protect our intellectual property if we are unable to enforce our rights or if we do not detect unauthorized use of our intellectual property. Despite our precautions, it may be possible for unauthorized third parties to copy Slack, or certain aspects of Slack, and use information that we regard as proprietary to create products that compete with Slack. Some license provisions protecting against unauthorized use, copying, transfer, and disclosure of Slack, or certain aspects of Slack, may be unenforceable under the laws of certain jurisdictions and foreign countries. Further, the laws of some countries do not protect proprietary rights to the same extent as the laws of the United States, and mechanisms for enforcement of intellectual property rights in some foreign countries may be inadequate. To the extent we expand our international activities, our exposure to unauthorized copying and use of Slack, or certain aspects of Slack, and proprietary information may increase. Further, competitors, foreign governments, foreign government-backed actors, criminals, or other third parties may gain unauthorized access to our proprietary information and technology. Accordingly, despite our efforts, we may be unable to prevent third parties from infringing upon or misappropriating our technology and intellectual property.

We rely in part on trade secrets, proprietary know-how, and other confidential information to maintain our competitive position. Although we enter into confidentiality and invention assignment agreements with our employees and consultants and enter into confidentiality agreements with the parties with whom we have strategic relationships and business alliances, no assurance can be given that these agreements will be effective in controlling access to and distribution of Slack, or certain aspects of Slack, and proprietary information. Further, these agreements do not prevent our competitors from independently developing technologies that are substantially equivalent or superior to Slack.

To protect our intellectual property rights, we may be required to spend significant resources to monitor and protect these rights, and we may or may not be able to detect infringement by third parties. Litigation may be necessary in the future to enforce our intellectual property rights and to protect our trade secrets. Such litigation could be costly, time consuming, and distracting to management and could result in the impairment or loss of portions of our intellectual property. Furthermore, our efforts to enforce our intellectual property rights may be met with defenses, counterclaims, and countersuits attacking the validity and enforceability of our intellectual property rights. Our inability to protect our proprietary technology against unauthorized copying or use, as well as any costly litigation or diversion of our management’s attention and resources, could delay further sales or the implementation of Slack, impair the functionality of Slack, delay introductions of new features, integrations, and capabilities, result in our substituting inferior or more

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costly technologies into Slack, or injure our reputation. In addition, we may be required to license additional technology from third parties to develop and market new features, integrations, and capabilities, and we cannot assure you that we could license that technology on commercially reasonable terms or at all, and our inability to license this technology could harm our ability to compete.

Our results of operations may be harmed if we are subject to a protracted infringement claim, a claim that results in a significant damage award, or a claim that results in an injunction.

There is considerable patent and other intellectual property development and enforcement activity in our industry. We expect that software product developers will increasingly be subject to infringement claims as the number of products and competitors grows and the functionality of products in different industry segments overlaps. Our future success depends in part on not infringing upon or misappropriating the intellectual property rights of others. Other companies have claimed in the past, and may claim in the future, that we infringe upon their intellectual property rights. A claim may also be made relating to technology that we acquire or license from third parties. If we were subject to a claim of infringement, regardless of the merit of the claim or our defenses, the claim could:

• require costly litigation to resolve and the payment of substantial damages;

• require and divert significant management time;

• cause us to enter into unfavorable royalty or license agreements;

• require us to discontinue some or all of the features, integrations, and capabilities available in Slack;

• require us to indemnify organizations on Slack or third-party service providers; and/or

• require us to expend additional development resources to redesign Slack or certain aspects of Slack.

Any one or more of the above could harm our business, results of operations, and financial condition.

We use open source software, which could negatively affect our ability to offer Slack and subject us to litigation or other actions.

We use substantial amounts of open source software in Slack and may use more open source software in the future. From time to time, there have been claims challenging both the ownership of open source software against companies that incorporate open source software into their products and whether such incorporation is permissible under various open source licenses. The terms of many open source licenses have not been interpreted by U.S. courts, and there is a risk that these licenses could be construed in a way that could impose unanticipated conditions or restrictions on our ability to commercialize Slack. As a result, we could be subject to lawsuits by parties claiming ownership of what we believe to be open source software, or breach of open source licenses. Litigation could be costly for us to defend, have a negative effect on our results of operations and financial condition, or require us to devote additional research and development resources to change Slack, or certain aspects of Slack. In addition, if we were to combine our proprietary source code or software with open source software in a certain manner, we could, under certain of the open source licenses, be required to release the source code of our proprietary software to the public. This would allow our competitors to create similar products with less development effort and time. If we inappropriately use open source software, or if the license terms for open source software that we use change, we may be required to re-engineer our Slack, or certain aspects of Slack, incur additional costs, discontinue the sale of Slack or the availability of certain features, integrations, or capabilities of Slack, or take other remedial actions.

In addition to risks related to license requirements, usage of open source software can lead to greater risks than use of third-party commercial software, as open source licensors generally do not provide warranties or assurance of title or controls on origin of the software. In addition, many of the risks associated with usage of open source software, such as the lack of warranties or assurances of title, cannot be eliminated, and could, if not properly addressed, negatively affect our business. We have established processes to help alleviate these risks, but we cannot be sure that all of our use of open source software is in a manner that is consistent with our current policies and procedures, or will not subject us to liability.

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Indemnity provisions in various agreements potentially expose us to substantial liability for intellectual property infringement and other losses.

Our agreements with organizations on Slack and other third parties may include indemnification or other provisions under which we agree to indemnify or otherwise be liable to them for losses suffered or incurred as a result of claims of intellectual property infringement, damages caused by us to property or persons, or other liabilities relating to or arising from the use of Slack or other acts or omissions. The term of these contractual provisions often survives termination or expiration of the applicable agreement. As we continue to grow, the possibility of these and other intellectual property rights claims against us may increase. For any intellectual property rights indemnification claim against us or organizations on Slack, we may incur significant legal expenses and may have to pay damages, license fees and/or stop using technology found to be in violation of the third party’s rights. Large indemnity payments could harm our business, results of operations, and financial condition. We may also have to seek a license for the technology. Such license may not be available on reasonable terms, if at all, and may significantly increase our operating expenses or may require us to restrict our business activities and limit our ability to deliver Slack and/or certain features, integrations, and capabilities of Slack. As a result, we may also be required to develop alternative non-infringing technology, which could require significant effort and expense and/or cause us to alter Slack, which could negatively affect our business.

From time to time, organizations on Slack may require us to indemnify or otherwise be liable to them for breach of confidentiality, violation of applicable law, or failure to implement adequate security measures with respect to their data stored, transmitted, or accessed using Slack. Although we normally contractually limit our liability with respect to such obligations, the existence of such a dispute may have adverse effects on our relationship with organizations on Slack and reputation or such limitations may not be honored in every jurisdiction and we may still incur substantial liability related to them.

Any assertions by a third party, whether or not successful, with respect to such indemnification obligations could subject us to costly and time-consuming litigation, expensive remediation and licenses, divert management attention and financial resources, harm our relationship with that organization on Slack and other current and prospective organizations, reduce demand for Slack, and harm our brand, business, results of operations, and financial condition.

We provide service level commitments under certain of our paid customer contracts. If we fail to meet these contractual commitments, we could be obligated to provide credits for future service, or face contract termination with refunds of prepaid amounts related to unused subscriptions, which could harm our business, results of operations, and financial condition.

Certain of our paid customer agreements contain service level agreements, under which we guarantee specified minimum availability of Slack. From time to time, we have granted credits to paid customers pursuant to the terms of these agreements. We do not currently have any material liabilities accrued on our balance sheet for these commitments. Any failure of or disruption to our infrastructure could make Slack unavailable to organizations on Slack. If we are unable to meet the stated service level commitments to our paid customers or suffer extended periods of unavailability of Slack, we may be contractually obligated to provide affected paid customers with service credits for future subscriptions, or paid customers could elect to terminate and receive refunds for prepaid amounts related to unused subscriptions. Our revenue, other results of operations, and financial condition could be harmed if we suffer unscheduled downtime that exceeds the service level commitments under our agreements with our paid customers, and any extended service outages could adversely affect our business and reputation as paid customers may elect not to renew and we could lose future sales.

We may be subject to liability claims if we breach our contracts and our insurance may be inadequate to cover our losses.

We are subject to numerous obligations in our contracts with organizations on Slack and our partners. Despite the procedures, systems and internal controls we have implemented to comply with our contracts, we may breach these commitments, whether through a weakness in these procedures, systems, and internal controls, negligence, or the willful act of an employee or contractor. Our insurance policies, including our errors and omissions insurance, may be inadequate to compensate us for the potentially significant losses that may result from claims arising from breaches of our contracts, disruptions in our services, failures or disruptions to our infrastructure, catastrophic events, and disasters or otherwise.

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In addition, such insurance may not be available to us in the future on economically reasonable terms, or at all. Further, our insurance may not cover all claims made against us and defending a suit, regardless of its merit, could be costly and divert management’s attention.

We may be subject to litigation for a variety of claims, which could harm our reputation and adversely affect our business, results of operations, and financial condition.

In the ordinary course of business, we may be involved in and subject to litigation for a variety of claims or disputes and receive regulatory inquiries. These claims, lawsuits, and proceedings could include labor and employment, wage and hour, commercial, antitrust, alleged securities law violations or other investor claims, and other matters. The number and significance of these potential claims and disputes may increase as our business expands. Further, our general liability insurance may not cover all potential claims made against us or be sufficient to indemnify us for all liability that may be imposed. Any claim against us, regardless of its merit, could be costly, divert management’s attention and operational resources, and harm our reputation. As litigation is inherently unpredictable, we cannot assure you that any potential claims or disputes will not have a material adverse effect on our business, results of operations, and financial condition.

We may be subject to federal and state health privacy laws and regulations. If we are unable to comply or have not fully complied with such laws and regulations, we could face government enforcement actions, civil penalties, criminal sanctions, or damages, which could harm our reputation and adversely affect our business.

We may function as a HIPAA business associate for certain of our paid customers and, as such, are subject to applicable privacy and data security requirements. If we fail to comply with any of these requirements, we could be subject to significant liability, which could harm our reputation and adversely affect our business as well as our ability to attract new and retain existing paid customers.

The Health Insurance Portability and Accountability Act of 1996, as amended by the Health Information Technology for Economic and Clinical Health Act, or HITECH, and their respective implementing regulations, or collectively, HIPAA, establish a set of federal privacy and security standards for the protection of individually identifiable health information that apply tohealth plans, healthcare clearinghouses, and healthcare providers that submit certain covered transactions, or “covered entities.” A subset of these standards also apply to ‘‘business associates,’’ which are persons or entities that perform certain services for, or on behalf of, a covered entity that involve creating, receiving, maintaining, or transmitting protected health information.

Certain of our paid customers are HIPAA covered entities and service providers, and in that context we may function as a business associate under HIPAA. Among other things, this status means that for certain activities we must comply with applicable administrative, technical, and physical safeguards as required by HIPAA, including stringent data security obligations. Failure to comply with HIPAA can result in significant civil monetary penalties and, in certain circumstances, criminal penalties with fines and/or imprisonment.

The HIPAA covered entities and service providers to whom we serve as a business associaterequire us to enter into HIPAA-compliant business associate agreements with them. If we are unable to comply with our obligations as a HIPAA business associate, we could face contractual liabilityunder the applicable business associate agreement.

In addition, many state laws govern the privacy and security of health information in certain circumstances, many of which differ from HIPAA. There may also be costs associated with responding to government investigations regarding alleged violations of these and other laws and regulations, even if there are ultimately no findings of violations or no penalties imposed. These costs can consume company resources and impact our business and, if public, harm our reputation.

If we are unable to meet the requirements of HIPAA, our business associate agreements or state health privacy laws, we could face contractual liability or civil and criminal liability under HIPAA, all of which can have an adverse impact on our business and generate negative publicity, which, in turn, can have an adverse impact on our ability to attract new paid customers and to grow or maintain our Net Dollar Retention Rate.

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We are subject to anti-corruption, anti-bribery, and similar laws, and non-compliance with such laws can subject us to criminal penalties or significant fines and harm our business and reputation.

We are subject to anti-corruption and anti-bribery and similar laws, such as the U.S. Foreign Corrupt Practices Act of 1977, as amended, or the FCPA, the U.S. domestic bribery statute contained in 18 U.S.C. § 201, U.S. Travel Act, the USA PATRIOT Act, the U.K. Bribery Act 2010, and other anti-corruption, anti-bribery and anti-money laundering laws in countries in which we conduct activities. Anti-corruption and anti-bribery laws have been enforced aggressively in recent years and are interpreted broadly and prohibit companies and their employees and agents from promising, authorizing, making, or offering improper payments or other benefits to government officials and others in the private sector. As we increase our international sales and business, our risks under these laws may increase. Noncompliance with these laws could subject us to investigations, sanctions, settlements, prosecution, other enforcement actions, disgorgement of profits, significant fines, damages, other civil and criminal penalties or injunctions, adverse media coverage, and other consequences. Any investigations, actions or sanctions could harm our business, results of operations, and financial condition.

In addition, in the future we may use third parties to sell access to Slack and conduct business on our behalf abroad. We or such future third-party intermediaries may have direct or indirect interactions with officials and employees of government agencies or state-owned or affiliated entities, and we can be held liable for the corrupt or other illegal activities of such future third-party intermediaries, and our employees, representatives, contractors, partners, and agents, even if we do not explicitly authorize such activities. We have implemented an anti-corruption compliance program but cannot assure you that all our employees and agents, as well as those companies to which we outsource certain of our business operations, will not take actions in violation of our policies and applicable law, for which we may be ultimately held responsible. Any violation of the FCPA, other applicable anti-corruption laws, or anti-money laundering laws could result in whistleblower complaints, adverse media coverage, investigations, loss of export privileges, severe criminal or civil sanctions and, in the case of the FCPA, suspension or debarment from U.S. government contracts, any of which could have a materially adverse effect on our reputation, business, results of operations, and prospects.

We are subject to governmental export controls and economic sanctions laws that could impair our ability to compete in international markets and subject us to liability if we are not in full compliance with applicable laws.

Some of our business activities may be subject to various restrictions under U.S. and E.U. export controls and trade and economic sanctions laws, including, among others, the U.S. Commerce Department’s Export Administration Regulations and economic and trade sanctions regulations maintained by the U.S. Treasury Department’s Office of Foreign Assets Control. U.S. and E.U. export control laws and U.S. and E.U. economic sanctions laws may prohibit or restrict the sale or supply of certain products, including encryption items and technology, and services to certain governments, persons, and entities and countries and territories, including those that are the target of comprehensive sanctions. In addition, various countries regulate the import of certain encryption technology, including through import permitting and licensing requirements, and have enacted laws that could limit our ability to distribute Slack or could limit the ability of organizations on Slack to implement Slack in those countries. Although we take precautions to prevent Slack from being provided in violation of such laws and regulations, we cannot guarantee that such precautions will be fully effective and Slack may have been in the past, and could in the future be, provided inadvertently in violation of such laws, despite the precautions we take. If we fail to comply with these laws and regulations, we and certain of our employees could be subject to civil or criminal penalties, government investigation, loss of export privileges, and reputational harm. Further, obtaining the necessary authorizations, including any required licenses, for a particular transaction may be time-consuming, is not guaranteed, and may result in the delay or loss of sales opportunities. Although we take precautions to prevent transactions with sanction targets, we cannot guarantee that such precautions will be fully effective and we could inadvertently provide Slack to persons prohibited by U.S. and E.U. sanctions, which could result in negative consequences to us, including government investigations, penalties, and harm to our reputation.

In addition, changes in Slack, or future changes in export and import regulations may prevent our users with international operations from using Slack globally or, in some cases, prevent the export or import of Slack to certain countries, governments, or persons altogether. Any change in export or import regulations, economic sanctions or related legislation, or change in the countries, governments, persons, or technologies targeted by such regulations, could result in decreased use of Slack by, or in our decreased ability to export or sell subscriptions to Slack to, existing or

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potential users with international operations. Any decreased use of Slack or limitation on our ability to export or sell Slack would likely adversely affect our business, results of operations and financial condition.

We are subject to a variety of U.S. and international laws that could subject us to claims, increase our operating expenses, or otherwise harm our business due to changes in the laws, changes in the interpretations of the laws, greater enforcement of the laws, or investigations into compliance with the laws.

We are subject to compliance with various laws, including those covering copyright, consumer protection, child protection, and similar matters. There have been instances where improper or illegal content has been stored on Slack without our knowledge. As a service provider, with some exceptions, we do not regularly monitor Slack to evaluate the legality of content stored on it. While to date we have not been subject to material legal or administrative actions as a result of the content stored on Slack or the activities conducted or organized using Slack, the laws in this area are currently in a state of flux and vary widely between jurisdictions. Accordingly, it may be possible that in the future we and our competitors may be subject to legal actions, along with the organizations on Slack and users who upload improper or illegal content, or engage in improper or illegal activities using Slack. In addition, regardless of any legal liability we may face, our reputation could be harmed should there be an incident generating negative publicity about the content stored on Slack, or the activities conducted or organized using Slack. Such publicity could harm our reputation and brand as well as our business, results of operations, and financial condition.

We may also be subject to consumer privacy or consumer protection laws that may impact our sales, marketing, and compliance efforts, including laws related to subscriptions, billing, and auto-renewal. These laws, as well as any changes in these laws, could adversely affect our free version of Slack and make it more difficult for us to grow or maintain our Net Dollar Retention Rate, upgrade organizations on Slack, and attract new organizations to Slack. Additionally, we have in the past, are currently, and may from time to time in the future become the subject of inquiries and other actions by regulatory authorities as a result of our business practices, including our subscription, billing, and auto-renewal policies. Consumer privacy and consumer protection laws may be interpreted or applied by regulatory authorities in a manner that could require us to make changes to Slack, our contracts, or our operations, or incur fines, penalties, or settlement expenses, which may result in harm to our business, results of operations, financial condition, and brand.

Further, in certain countries, we may be classified as a telecommunications service provider, or our classification may be uncertain. Such classification as a telecommunications service provider could restrict our ability to operate in such markets without appropriate local authorization, or at all.

We are also subject to other U.S. and international laws. Although we take precautions to prevent violations of these laws, our exposure for violating these laws increases as we continue to expand our international presence and any failure to comply with such laws could harm our reputation and our business.

Action by governments to restrict access to Slack in their countries or to require us to disclose or provide access to information in our possession could harm our business, results of operations, and financial condition.

Slack depends on the ability of our users to access the Internet and Slack could be blocked or restricted in some countries for various reasons. Further, it is possible that governments of one or more foreign countries may seek to limit access to or certain features of Slack in their countries, or impose other restrictions that may affect the availability of Slack, or certain features of Slack, in their countries for an extended period of time or indefinitely. For example, Russia and China are among a number of countries that have recently blocked certain online services, including AWS, which hosts Slack, making it very difficult for such services to access those markets. In addition, governments in certain countries may seek to restrict or prohibit access to Slack if they consider us to be in violation of their laws and may require us to disclose or provide access to information in our possession. If we fail to anticipate developments in the law, or fail for any reason to comply with relevant law, Slack could be further blocked or restricted and we could be exposed to significant liability that could harm our business. In the event that access to Slack is restricted, in whole or in part, in one or more countries or our competitors are able to successfully penetrate geographic markets that we cannot access, our ability to grow or maintain our Net Dollar Retention Rate may be adversely affected, we may not be able to maintain or grow our revenue as anticipated and our business, results of operations, and financial condition could be adversely affected.

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Because our success depends, in part, on our ability to expand sales of Slack to organizations located outside of the United States, our business will be susceptible to risks associated with international operations.

We currently maintain offices and have sales personnel outside the United States in Australia, Canada, Ireland, India, Japan, and the United Kingdom, and we intend to expand our international operations. In fiscal years 2017, 2018, and 2019, our non-U.S. revenue was 34%, 34%, and 36% of our total revenue, respectively. We expect to continue to expand our international operations, which may include opening offices in new jurisdictions and providing Slack in additional languages. Any additional international expansion efforts that we are undertaking and may undertake may not be successful. In addition, conducting international operations subjects us to new risks, some of which we have not generally faced in the United States or in other countries where we currently operate. These risks include, among other things:

• unexpected costs and errors in the localization of Slack, including translation into foreign languages and adaptation for local culture, practices, and regulatory requirements;

• lack of familiarity and burdens of complying with foreign laws, legal standards, privacy standards, regulatory requirements, tariffs, and other barriers, and the risk of penalties to our users and individual members of management or employees if our practices are deemed to be out of compliance;

• practical difficulties of enforcing intellectual property rights in countries with varying laws and standards and reduced or varied protection for intellectual property rights in some countries;

• an evolving legal framework and additional legal or regulatory requirements for data privacy, which may necessitate the establishment of systems to maintain data in local markets, requiring us to invest in additional data centers and network infrastructure, and the implementation of additional employee data privacy documentation (including locally-compliant data privacy notice and policies), all of which may involve substantial expense and may cause us to need to divert resources from other aspects of our business, all of which may adversely affect our business;

• as a U.S. company, we are subject to U.S. laws concerning governmental access to data and the risk, or perception of risk, of such access may make Slack less attractive to organizations outside the U.S., and compliance with such U.S. laws may conflict with legal obligations that we, or our organizations on Slack, may be subject to in other countries;

• unexpected changes in regulatory requirements, taxes, trade laws, tariffs, export quotas, custom duties, or other trade restrictions;

• difficulties in managing systems integrators and technology partners;

• differing technology standards;

• longer accounts receivable payment cycles and difficulties in collecting accounts receivable;

• increased financial accounting and reporting burdens and complexities;

• difficulties in managing and staffing international operations including the proper classification of independent contractors and other contingent workers, differing employer/employee relationships, and local employment laws;

• increased costs involved with recruiting and retaining an expanded employee population outside the United States through cash and equity-based incentive programs and unexpected legal costs and regulatory restrictions in issuing our shares to employees outside the United States;

• global political and regulatory changes that may lead to restrictions on immigration and travel for our employees outside the United States;

• fluctuations in exchange rates that may decrease the value of our foreign-based revenue;

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• potentially adverse tax consequences, including the complexities of foreign value added tax (or other tax) systems, and restrictions on the repatriation of earnings; and

• permanent establishment risks and complexities in connection with international payroll, tax, and social security requirements for international employees.

Additionally, operating in international markets also requires significant management attention and financial resources. We cannot be certain that the investment and additional resources required in establishing operations in other countries will produce desired levels of revenue or profitability.

Further, we have not engaged in currency hedging activities to limit risk of exchange rate fluctuations. Changes in exchange rates affect our costs and earnings, and may also affect the book value of our assets located outside the United States and the amount of our stockholders’ equity.

Compliance with laws and regulations applicable to our global operations also substantially increases our cost of doing business in foreign jurisdictions. We have limited experience in marketing, selling, and supporting Slack outside of the United States. Our limited experience in operating our business internationally increases the risk that any potential future expansion efforts that we may undertake will not be successful. If we invest substantial time and resources to expand our international operations and are unable to do so successfully and in a timely manner, our business, results of operations, and financial condition will suffer. We may be unable to keep current with changes in government requirements as they change from time to time. Failure to comply with these regulations could harm our business. In many countries, it is common for others to engage in business practices that are prohibited by our internal policies and procedures or other regulations applicable to us. Although we have implemented policies and procedures designed to ensure compliance with these laws and policies, there can be no assurance that all of our employees, contractors, partners, and agents will comply with these laws and policies. Violations of laws or key control policies by our employees, contractors, partners, or agents could result in delays in revenue recognition, financial reporting misstatements, enforcement actions, reputational harm, disgorgement of profits, fines, civil and criminal penalties, damages, injunctions, other collateral consequences, or the prohibition of the importation or exportation of Slack and could harm our business, results of operations, and financial condition.

We may face exposure to foreign currency exchange rate fluctuations.

Today, our contracts with paid customers outside of the United States are sometimes denominated in local currencies. In addition, the majority of our foreign costs are denominated in local currencies. Over time, an increasing portion of our contracts with paid customers outside of the United States may be denominated in local currencies. Therefore, fluctuations in the value of the U.S. dollar and foreign currencies may affect our results of operations when translated into U.S. dollars. We do not currently engage in currency hedging activities to limit the risk of exchange rate fluctuations. However, in the future, we may use derivative instruments, such as foreign currency forward and option contracts, to hedge certain exposures to fluctuations in foreign currency exchange rates. The use of such hedging activities may not offset any or more than a portion of the adverse financial effects of unfavorable movements in foreign exchange rates over the limited time the hedges are in place. Moreover, the use of hedging instruments may introduce additional risks if we are unable to structure effective hedges with such instruments.

Exposure to political developments in the United Kingdom, including the outcome of the U.K. referendum on membership in the European Union, could harm us.

On June 23, 2016, a referendum was held on the United Kingdom’s membership in the European Union, the outcome of which was a vote in favor of leaving the European Union. The United Kingdom’s vote to leave the European Union has created an uncertain political and economic environment in the United Kingdom and across other European Union member states. The result of the referendum means that the long-term nature of the United Kingdom’s relationship with the European Union is unclear and that there is considerable uncertainty as to whether and when any such relationship will be agreed and implemented. The political and economic instability created by the United Kingdom’s vote to leave the European Union has caused and may continue to cause significant volatility in global financial markets and the value of the British Pound or other currencies, including the Euro. Depending on the terms reached regarding any exit from the European Union, or if no such terms are reached, it is possible that there may be adverse practical or operational implications on our business. For example, the UK Data Protection Act that substantially implements the

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GDPR became effective in May 2018. It remains unclear, however, how United Kingdom data protection laws or regulations will develop in the medium to longer term and how data transfers to and from the United Kingdom will be regulated and how those regulations may differ from those in the European Union. Further, the United Kingdom’s exit from the European Union may create increased compliance costs and an uncertain regulatory landscape for offering equity-based incentives to our employees in the United Kingdom. If we are unable to maintain equity-based incentive programs for our employees in the United Kingdom due to the departure of the United Kingdom from the European Union, our business in the United Kingdom may suffer and we may face legal claims from employees in the United Kingdom to whom we previously offered equity-based incentive programs.

Our activities in the United States subject us to various laws relating to foreign investment and the export of certain technologies, and our failure to comply with these laws or adequately monitor the compliance of our suppliers and others we do business with could subject us to fines, penalties, and even injunctions, the imposition of which on us could have a material adverse effect on the success of our business.

Because we are a U.S. business with substantial operations in the United States, we may be subject to U.S. laws that regulate foreign investments in U.S. businesses and access by foreign persons to technology developed and produced in the United States. These laws include Section 721 of the Defense Production Act of 1950, as amended by the Foreign Investment Risk Review Modernization Act of 2018, and the regulations at 31 C.F.R. Parts 800 and 801, as amended, administered by the Committee on Foreign Investment in the United States; and the Export Control Reform Act of 2018, which is being implemented in part through Commerce Department rulemakings to impose new export control restrictions on “emerging and foundational technologies” yet to be fully identified. Application of these laws, including as they are implemented through regulations being developed, may negatively impact our business in various ways, including by restricting our access to capital and markets; limiting the collaborations we may pursue; regulating the export of our service and technology from the United States and abroad; increasing our costs and the time necessary to obtain required authorizations and to ensure compliance; and threatening monetary fines and other penalties if we do not.

We may be required to defer recognition of some of our revenue, which may harm our financial results in any given period.

We may be required to defer recognition of revenue for a significant period of time after entering into an agreement due to a variety of factors, including, among other things, whether:

• the paid customer fails to deploy Slack to as many users as contemplated in the agreement given that, in many of our transactions, revenue is reduced in the form of fair billing credits we provide to paid customers when a user becomes inactive;

• contract modification is granted to reduce commitment or to lower fees because of frequent service interruptions or because Slack did not meet the paid customer’s needs or expectations;

• service outages result in failure to meet our monthly uptime guarantee because revenue is reduced when we compensate paid customers in the form of credits promised under our service level agreements;

• the transaction includes an option to renew at significantly higher discounts than what was provided under existing agreement and other comparable transactions;

• the transaction is contingent on future functionality that is not delivered within the paid customer’s expected timeline; or

• the transaction involves acceptance criteria or other contingencies that may delay revenue recognition.

Because of these factors and other specific revenue recognition requirements under GAAP, we must have very precise terms in our contracts to recognize revenue when we initially provide access to Slack or perform services. Although we strive to enter into agreements that meet the criteria under GAAP for current revenue recognition on delivered elements, our agreements are often subject to negotiation and revision based on the demands of our paid customers. The final terms of our agreements sometimes result in deferred revenue recognition well after the time of delivery, which may adversely affect our financial results in any given period.

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Furthermore, the presentation of our financial results requires us to make estimates and assumptions that may affect the timing of revenue recognition as well as how revenue is allocated between revenue categories. In some instances, we could reasonably use different estimates and assumptions, and changes in estimates are likely to occur from period to period as new updated information becomes available or when there is a change in prevailing conditions. Accordingly, actual results could differ significantly from our estimates.

We have limited experience with respect to determining the optimal prices for Slack.

We have limited experience with respect to determining the optimal prices for Slack and, as a result, we have in the past, and expect in the future, that we will need to change our pricing model from time to time. In the past, we have sometimes adjusted our prices either for individual paid customers in connection with long-term agreements or unique situations. Moreover, demand for Slack is also sensitive to price. Many factors, including our marketing, user acquisition and technology costs, and our current and future competitors’ pricing and marketing strategies, can significantly affect our pricing strategies. Further, certain of our competitors offer, or may in the future offer, lower-priced or free products or services that compete with Slack or may bundle functionality compatible with Slack and offer a broader range of products and services. Similarly, certain competitors may use marketing strategies that enable them to acquire users more rapidly or at a lower cost than us, or both, and we may be unable to attract new users and organizations or grow or maintain our Net Dollar Retention Rate based on our historical pricing. As we expand internationally, we also must determine the appropriate price to enable us to compete effectively internationally. In addition, if our mix of features, integrations, and capabilities on Slack changes or we develop additional versions for specific use cases or additional premium versions, then we may need to, or choose to, revise our pricing. There can be no assurance that we will not be forced to engage in price-cutting initiatives or to increase our marketing and other expenses to attract users and organizations to Slack and to grow or maintain our Net Dollar Retention Rate in response to competitive or other pressures, either of which could materially and adversely affect our business, results of operations, and financial condition.

Future acquisitions, strategic investments, partnerships, or alliances could be difficult to identify and integrate, divert the attention of key management personnel, disrupt our business, dilute stockholder value, and harm our results of operations and financial condition.

We have in the past acquired, and we may in the future seek to acquire or invest in, businesses, products, or technologies that we believe could complement Slack or expand its breadth, enhance our technical capabilities, or otherwise offer growth opportunities. The pursuit of potential acquisitions may divert the attention of management and cause us to incur various expenses in identifying, investigating, and pursuing suitable acquisitions, whether or not they are consummated. Any acquisition, investment or business relationship may result in unforeseen operating difficulties and expenditures. In addition, we have limited experience in acquiring other businesses. If we acquire additional businesses, we may not be able to integrate successfully the acquired personnel, operations, and technologies, or effectively manage the combined business following the acquisition. Specifically, we may not successfully evaluate or utilize the acquired technology or personnel, or accurately forecast the financial impact of an acquisition transaction, including accounting charges. Moreover, the anticipated benefits of any acquisition, investment, or business relationship may not be realized or we may be exposed to unknown risks or liabilities.

We may not be able to find and identify desirable acquisition targets or we may not be successful in entering into an agreement with any one target. Acquisitions could also result in dilutive issuances of equity securities or the incurrence of debt, which could harm our results of operations. In addition, if an acquired business fails to meet our expectations, our business, results of operations, and financial condition may suffer.

We also make strategic investments in early stage companies developing products or technologies that we believe could complement Slack or expand its breadth, enhance our technical capabilities, or otherwise offer growth opportunities through our subsidiary, Slack Fund. These investments are generally in early stage private companies for restricted stock. Such investments are generally illiquid and may never generate value. Further, the companies in which we invest may not succeed, and our investments would lose their value.

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We depend on our executive officers and other key employees, and the loss of one or more of these employees or an inability to attract and retain other highly skilled employees could harm our business.

Our success depends largely upon the continued services of our executive officers and other key employees. We rely on our leadership team in the areas of research and development, operations, security, marketing, sales, customer experience, general, and administrative functions, and on individual contributors in our research and development and operations. From time to time, there may be changes in our executive management team resulting from the hiring or departure of executives, which could disrupt our business. We do not have employment agreements with our executive officers or other key personnel that require them to continue to work for us for any specified period and, therefore, they could terminate their employment with us at any time. The loss of one or more of our executive officers, especially our Chief Executive Officer, or key employees could harm our business. Changes in our executive management team may also cause disruptions in, and harm to, our business.

In addition, to execute our growth plan, we must attract and retain highly qualified personnel. Competition for these personnel in the San Francisco Bay Area, where our headquarters is located, and in other locations where we maintain offices, is intense, especially for engineers experienced in designing and developing software and Software-as-a-Service applications and experienced sales professionals. We have, from time to time experienced, and we expect to continue to experience, difficulty in hiring and retaining employees with appropriate qualifications. In addition, certain domestic immigration laws restrict or limit our ability to recruit internationally. Any changes to U.S. immigration policies that restrain the flow of technical and professional talent may inhibit our ability to recruit and retain highly qualified employees. Many of the companies with which we compete for experienced personnel have greater resources than we have. If we hire employees from competitors or other companies, their former employers may attempt to assert that these employees or we have breached their legal obligations, resulting in a diversion of our time and resources. In addition, job candidates and existing employees often consider the value of the equity awards they receive in connection with their employment. If the perceived value of our equity awards declines, it may harm our ability to recruit and retain highly skilled employees. If we fail to attract new personnel or fail to retain and motivate our current personnel, our business and future growth prospects could be harmed. Meanwhile, additions of executive-level management and large numbers of employees could significantly and adversely impact our culture.

Volatility or lack of appreciation in the stock price of our Class A common stock may also affect our ability to attract and retain our key employees. Many of our senior personnel and other key employees have become, or will soon become, vested in a substantial amount of stock or stock options. Employees may be more likely to leave us if the shares they own or the shares underlying their vested options or restricted stock units, or RSUs, have significantly appreciated in value relative to the original purchase price of the shares or the exercise price of the options, or conversely, if the exercise price of the options that they hold are significantly above the market price of our Class A common stock. If we do not maintain and continue to develop our corporate culture as we grow and evolve, it could harm our ability to foster the innovation, craftsmanship, teamwork, curiosity, and diversity, we believe that we need to support our growth.

Our management team has limited experience managing a public company.

Most members of our management team have limited experience managing a publicly-traded company, interacting with public company investors and complying with the increasingly complex laws pertaining to public companies. Our management team may not successfully or efficiently manage our transition to being a public company that is subject to significant regulatory oversight and reporting obligations under the federal securities laws and the continuous scrutiny of securities analysts and investors. These new obligations and constituents will require significant attention from our senior management and could divert their attention away from the day-to-day management of our business, which could harm our business, results of operations, and financial condition.

Catastrophic events may disrupt our business.

Natural disasters or other catastrophic events may cause damage or disruption to our operations, international commerce, and the global economy, and thus could harm our business. We have our headquarters and a large employee presence in San Francisco, California and the west coast of the United States contains active earthquake zones. In the event of a major earthquake, hurricane, or catastrophic event such as fire, power loss, telecommunications failure, cyber-attack, war, or terrorist attack, we may be unable to continue our operations and may endure system interruptions,

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reputational harm, delays in our application development, lengthy interruptions in Slack, breaches of data security, and loss of critical data, all of which could harm our business, results of operations, and financial condition. Acts of terrorism could also cause disruptions to the Internet or the economy as a whole. In addition, the insurance we maintain would likely not be adequate to cover our losses resulting from disasters or other business interruptions.

Our failure to raise additional capital or generate cash flows necessary to expand our operations and invest in new technologies in the future could reduce our ability to compete successfully and harm our results of operations.

Historically, we have funded our operations and capital expenditures primarily through equity issuances and cash generated from our operations. Although we currently anticipate that our existing cash and cash equivalents and cash flow from operations will be sufficient to meet our cash needs for the foreseeable future, we may require additional financing, and we may not be able to obtain debt or equity financing on favorable terms, if at all. If we raise equity financing to fund operations or on an opportunistic basis, our stockholders may experience significant dilution of their ownership interests. If we engage in debt financing, we may be required to accept terms that restrict our ability to incur additional indebtedness, force us to maintain specified liquidity or other ratios or restrict our ability to pay dividends or make acquisitions. If we need additional capital and cannot raise it on acceptable terms, or at all, we may not be able to, among other things:

• develop new features, integrations, capabilities, and enhancements;

• continue to expand our product development, sales, and marketing organizations;

• hire, train, and retain employees;

• respond to competitive pressures or unanticipated working capital requirements; or

• pursue acquisition opportunities.

Changes in laws and regulations related to the Internet or changes in the Internet infrastructure itself may diminish the demand for Slack, and could harm our business.

The future success of our business depends upon the continued use of the Internet as a primary medium for commerce, communication, and business applications. Federal, state, or foreign government bodies or agencies have in the past adopted, and may in the future adopt, laws or regulations affecting the use of the Internet as a commercial medium. The adoption of any laws or regulations that could reduce the growth, popularity, or use of the Internet, including laws or practices limiting Internet neutrality, could decrease the demand for, or the usage of, Slack and services, increase our cost of doing business and harm our results of operations. Changes in these laws or regulations could require us to modify Slack, or certain aspects of Slack, in order to comply with these changes. In addition, government agencies or private organizations have imposed and may impose additional taxes, fees, or other charges for accessing the Internet or commerce conducted via the Internet. These laws or charges could limit the growth of Internet-related commerce or communications generally, or result in reductions in the demand for Internet-based products such as ours. In addition, the use of the Internet as a business tool could be harmed due to delays in the development or adoption of new standards and protocols to handle increased demands of Internet activity, security, reliability, cost, ease-of-use, accessibility, and quality of service. Further, Slack depends on the quality of our users’ access to the Internet. Certain features of Slack require significant bandwidth and fidelity to work effectively. Internet access is frequently provided by companies that have significant market power that could take actions that degrade, disrupt or increase the cost of user access to Slack, which would negatively impact our business. The performance of the Internet and its acceptance as a business tool has been harmed by “viruses,” “worms” and similar malicious programs and the Internet has experienced a variety of outages and other delays as a result of damage to portions of its infrastructure. If the use of the Internet is adversely affected by these issues, demand for Slack could decline.

If we fail to maintain an effective system of disclosure controls and internal control over financial reporting, our ability to produce timely and accurate financial statements or comply with applicable regulations could be impaired.

The Sarbanes-Oxley Act requires, among other things, that we maintain effective disclosure controls and procedures and internal control over financial reporting. We are continuing to develop and refine our disclosure controls and other procedures that are designed to ensure that information required to be disclosed by us in the reports that we will file

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with the SEC is recorded, processed, summarized, and reported within the time periods specified in SEC rules and forms and that information required to be disclosed in reports under the Securities Exchange Act of 1934, as amended, or the Exchange Act, is accumulated and communicated to our principal executive and financial officers. We are also continuing to improve our internal control over financial reporting. For example, as we have prepared to become a public company, we have worked to improve the controls around our key accounting processes and our quarterly close process, we have implemented a number of new systems to supplement our core enterprise resource planning, or ERP, system as part of our control environment, and we have hired additional accounting and finance personnel to help us implement these processes and controls. In order to maintain and improve the effectiveness of our disclosure controls and procedures and internal control over financial reporting, we have expended, and anticipate that we will continue to expend, significant resources, including accounting-related costs and significant management oversight. If any of these new or improved controls and systems do not perform as expected, we may experience material weaknesses in our controls. In addition to our results determined in accordance with GAAP, we believe certain non-GAAP measures and key metrics may be useful in evaluating our operating performance. We present certain non-GAAP financial measures and key metrics in this prospectus and intend to continue to present certain non-GAAP financial measures and key metrics in future filings with the SEC and other public statements. Any failure to accurately report and present our non-GAAP financial measures and key metrics could cause investors to lose confidence in our reported financial and other information, which would likely have a negative effect on the trading price of our Class A common stock.

Our current controls and any new controls that we develop may become inadequate because of changes in conditions in our business. Further, weaknesses in our disclosure controls and internal control over financial reporting may be discovered in the future. Any failure to develop or maintain effective controls or any difficulties encountered in their implementation or improvement could harm our results of operations or cause us to fail to meet our reporting obligations and may result in a restatement of our consolidated financial statements for prior periods. Any failure to implement and maintain effective internal control over financial reporting also could adversely affect the results of periodic management evaluations and annual independent registered public accounting firm attestation reports regarding the effectiveness of our internal control over financial reporting that we will eventually be required to include in our periodic reports that will be filed with the SEC. Ineffective disclosure controls and procedures and internal control over financial reporting could also cause investors to lose confidence in our reported financial and other information, which would likely have a negative effect on the trading price of our Class A common stock. In addition, if we are unable to continue to meet these requirements, we may not be able to remain listed on the NYSE. We are not currently required to comply with the SEC rules that implement Section 404 of the Sarbanes-Oxley Act and are therefore not required to make a formal assessment of the effectiveness of our internal control over financial reporting for that purpose. As a public company, we will be required to provide an annual management report on the effectiveness of our internal control over financial reporting commencing with our second annual report on Form 10-K.

Our independent registered public accounting firm is not required to formally attest to the effectiveness of our internal control over financial reporting until after we are no longer an “emerging growth company” as defined in the JOBS Act. At such time, our independent registered public accounting firm may issue a report that is adverse in the event it is not satisfied with the level at which our internal control over financial reporting is documented, designed or operating. Any failure to maintain effective disclosure controls and internal control over financial reporting could harm our business, results of operations, and financial condition and could cause a decline in the price of our Class A common stock.

We are an “emerging growth company,” and the reduced disclosure requirements applicable to “emerging growth companies” may make our Class A common stock less attractive to investors.

We are an “emerging growth company,” as defined in the JOBS Act, and we intend to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not “emerging growth companies,” including not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act, reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements, and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved. We may take advantage of these exemptions until we are no longer an “emerging growth company,” which could be as long as five full fiscal years following the listing of our Class A common stock on the NYSE. We cannot predict if investors will find our Class A common stock less attractive because we will rely on these exemptions. If some investors find our

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Class A common stock less attractive as a result, there may be a less active trading market for our Class A common stock and the price of our Class A common stock may be more volatile.

We recently implemented a new enterprise resource planning system, and if this new system proves ineffective or if we experience issues with the transition, we may be unable to timely or accurately prepare financial reports, make payments to our suppliers and employees, or invoice and collect from our users.

In fiscal year 2019, we implemented a new ERP system, including our systems for tracking revenue recognition. Our ERP system is critical to our ability to accurately maintain books and records and to prepare our consolidated financial statements. The transition to our new ERP system may be disruptive to our business if the ERP system does not work as planned or if we experience issues relating to the implementation. Such disruptions could impact our ability to timely or accurately make payments to our suppliers and employees, and could also inhibit our ability to invoice, and collect from our users. Data integrity problems or other issues may be discovered which, if not corrected, could impact our business or financial results. In addition, we may experience periodic or prolonged disruption of our financial functions arising out of this conversion, general use of such system, other periodic upgrades or updates, or other external factors that are outside of our control. If we encounter unforeseen problems with our ERP system or other related systems and infrastructure, our business, results of operations, and financial condition could be adversely affected.

Changes in existing financial accounting standards or practices may harm our results of operations.

Changes in existing accounting rules or practices, new accounting pronouncements rules, or varying interpretations of current accounting pronouncements practice could harm our results of operations or the manner in which we conduct our business. Further, such changes could potentially affect our reporting of transactions completed before such changes are effective.

GAAP is subject to interpretation by the Financial Accounting Standards Board, or FASB, the SEC and various bodies formed to promulgate and interpret appropriate accounting principles. A change in these principles or interpretations could have a significant effect on our reported financial results, and could affect the reporting of transactions completed before the announcement of a change. In particular, in February 2016, the FASB issued Accounting Standards Codification, or ASC, 842, which supersedes the lease accounting guidance in ASC 840, Leases. The core principle of ASC 842 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. As an “emerging growth company,” we are allowed under the JOBS Act to delay adoption of new or revised accounting pronouncements applicable to public companies until such pronouncements are made applicable to private companies. We have elected to take advantage of this extended transition period under the JOBS Act with respect to ASC 842, which will result in ASC 842 becoming effective for us beginning on February 1, 2020 unless we choose to adopt it earlier. Any difficulties in implementing these pronouncements could cause us to fail to meet our financial reporting obligations, which could result in regulatory discipline and harm investors’ confidence in us.

We are evaluating ASC 842 and have not determined the impact it may have on our financial reporting.

If our estimates or judgments relating to our critical accounting policies prove to be incorrect, our results of operations could be adversely affected.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in our consolidated financial statements and related notes. We base our estimates on historical experience and on various other assumptions that we believe to be reasonable under the circumstances, as provided in the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations.” The results of these estimates form the basis for making judgments about the carrying values of assets, liabilities and equity, and the amount of revenue and expenses that are not readily apparent from other sources. Significant assumptions and estimates used in preparing our consolidated financial statements include those related to revenue recognition, stock-based compensation including the estimation of fair value of common stock, valuation of strategic investments, period of benefit for deferred costs, and uncertain tax positions. Our results of operations may

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be adversely affected if our assumptions change or if actual circumstances differ from those in our assumptions, which could cause our results of operations to fall below the expectations of securities analysts and investors, resulting in a decline in the trading price of our Class A common stock.

Changes in tax laws or regulations in the various tax jurisdictions we are subject to that are applied adversely to us or our paid customers could increase the costs of Slack and harm our business.

New income, sales, use or other tax laws, statutes, rules, regulations, or ordinances could be enacted at any time. Those enactments could harm our domestic and international business operations, and our business, results of operations, and financial condition. Further, existing tax laws, statutes, rules, regulations, or ordinances could be interpreted, changed, modified, or applied adversely to us. These events could require us or our paid customers to pay additional tax amounts on a prospective or retroactive basis, as well as require us or our paid customers to pay fines and/or penalties and interest for past amounts deemed to be due. If we raise our prices to offset the costs of these changes, existing and potential future paid customers may elect not to purchase Slack in the future. Additionally, new, changed, modified, or newly interpreted or applied tax laws could increase our paid customers’ and our compliance, operating, and other costs, as well as the costs of Slack. Further, these events could decrease the capital we have available to operate our business. Any or all of these events could harm our business, results of operations, and financial condition.

On December 22, 2017, the legislation commonly referred to as the Tax Cuts and Jobs Act, or the Tax Act, was enacted, which contains significant changes to U.S. tax law, including, but not limited to, a reduction in the corporate tax rate and a transition to a modified territorial system of taxation. The primary impact of the new legislation on our provision for income taxes was a reduction of the future tax benefits of our deferred tax assets as a result of the reduction in the corporate tax rate. However, since we have recorded a full valuation allowance against our deferred tax assets, we do not currently anticipate that these changes will have a material impact on our consolidated financial statements. The impact of the Tax Act will likely be subject to ongoing technical guidance and accounting interpretation, which we will continue to monitor and assess. As we expand the scale of our international business activities, any changes in the U.S. or foreign taxation of such activities may increase our worldwide effective tax rate and harm our business, results of operations, and financial condition.

Additionally, the application of U.S. federal, state, local, and international tax laws to services provided electronically is unclear and continuously evolving. Existing tax laws, statutes, rules, regulations, or ordinances could be interpreted or applied adversely to us, possibly with retroactive effect, which could require us or our paid customers to pay additional tax amounts, as well as require us or our paid customers to pay fines or penalties, as well as interest for past amounts. If we are unsuccessful in collecting such taxes due from our paid customers, we could be held liable for such costs, thereby adversely affecting our results of operations and harming our business.

As a multinational organization, we may be subject to taxation in several jurisdictions around the world with increasingly complex tax laws, the application of which can be uncertain. The amount of taxes we pay in these jurisdictions could increase substantially as a result of changes in the applicable tax principles, including increased tax rates, new tax laws, or revised interpretations of existing tax laws and precedents, which could harm our liquidity and results of operations. In addition, the authorities in these jurisdictions could review our tax returns and impose additional tax, interest, and penalties, and the authorities could claim that various withholding requirements apply to us or our subsidiaries or assert that benefits of tax treaties are not available to us or our subsidiaries, any of which could harm us and our results of operations.

Our results of operations may be harmed if we are required to collect sales or other related taxes for subscriptions to Slack in jurisdictions where we have not historically done so.

States and some local taxing jurisdictions have differing rules and regulations governing sales and use taxes, and these rules and regulations are subject to varying interpretations that may change over time. The application of federal, state, local, and international tax laws to services provided electronically is evolving. In particular, the applicability of sales taxes to Slack in various jurisdictions is unclear. We collect and remit U.S. sales and value-added tax, or VAT, in a number of jurisdictions. It is possible, however, that we could face sales tax or VAT audits and that our liability for these taxes could exceed our estimates as state tax authorities could still assert that we are obligated to collect additional tax amounts from our paid customers and remit those taxes to those authorities. We could also be subject to audits in states and international jurisdictions for which we have not accrued tax liabilities. A successful assertion that we should

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be collecting additional sales or other taxes on our services in jurisdictions where we have not historically done so and do not accrue for sales taxes could result in substantial tax liabilities for past sales, discourage organizations from subscribing to Slack, or otherwise harm our business, results of operations, and financial condition.

Further, one or more state or foreign authorities could seek to impose additional sales, use or other tax collection and record-keeping obligations on us or may determine that such taxes should have, but have not been, paid by us. Liability for past taxes may also include substantial interest and penalty charges. Any successful action by state, foreign, or other authorities to compel us to collect and remit sales tax, use tax or other taxes, either retroactively, prospectively or both, could harm our business, results of operations, and financial condition.

Our ability to use our net operating loss carryforwards and certain other tax attributes may be limited.

Under Section 382 of the Internal Revenue Code of 1986, as amended, or the Code, if a corporation undergoes an “ownership change,” generally defined as a greater than 50 percentage point change (by value) in its equity ownership over a three-year period, 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 taxable income or tax liability may be limited. We have experienced ownership changes in the past and, although we do not expect to experience an ownership change in connection with our listing on the NYSE, any such ownership change could result in increased future tax liability. In addition, we may experience ownership changes in the future as a result of subsequent shifts in our stock ownership. As a result, if we earn net taxable income, our ability to use our pre-change net operating loss carryforwards and other pre-change tax attributes to offset U.S. federal taxable income or tax liability may be subject to limitations, which could potentially result in increased future tax liability to us. In addition, under the Tax Act, the amount of post 2017 net operating loss carryforward that we are permitted to use in any taxable year is limited to 80% of our taxable income in such year, where taxable income is determined without regard to the net operating loss deduction itself. The Tax Act also generally eliminates the ability to carry back net operating losses to prior taxable years. For these reasons, we may not be able to realize a tax benefit from the use of our net operating losses even if we attain profitability.

Risks Related to Ownership of Our Class A Common Stock

Our listing differs significantly from an underwritten initial public offering.

This is not an underwritten initial public offering of our Class A common stock. This listing of our Class A common stock on the NYSE differs from an underwritten initial public offering in several significant ways, which include, but are not limited to, the following:

• There are no underwriters. Consequently, prior to the opening of trading on the NYSE, there will be no book building process and no price at which underwriters initially sold shares to the public to help inform efficient and sufficient price discovery with respect to the opening trades on the NYSE. Therefore, buy and sell orders submitted prior to and at the opening of trading of our Class A common stock on the NYSE will not have the benefit of being informed by a published price range or a price at which the underwriters initially sold shares to the public, as would be the case in an underwritten initial public offering. Moreover, there will be no underwriters assuming risk in connection with the initial resale of shares of our Class A common stock. Additionally, because there are no underwriters, there is no underwriters’ option to purchase additional shares to help stabilize, maintain, or affect the public price of our Class A common stock on the NYSE immediately after the listing. In an underwritten initial public offering, the underwriters may engage in “covered” short sales in an amount of shares representing the underwriters’ option to purchase additional shares. To close a covered short position, the underwriters purchase shares in the open market or exercise the underwriters’ option to purchase additional shares. In determining the source of shares to close the covered short position, the underwriters typically consider, among other things, the price of shares available for purchase in the open market as compared to the price at which they may purchase shares through the underwriters’ option to purchase additional shares. Purchases in the open market to cover short positions, as well as other purchases underwriters may undertake for their own accounts, may have the effect of preventing a decline in the market price of shares. Given that there will be no underwriters’ option to purchase additional shares and no underwriters engaging in stabilizing transactions, there could be greater volatility in the public price of our Class A common stock during the period immediately following the listing. See also “—The public price of our Class A common stock may be volatile, and could, upon listing on the NYSE, decline significantly and rapidly.”

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• There is not a fixed or determined number of shares of Class A common stock available for sale in connection with the registration and the listing, except we expect approximately          shares of our Class A common stock to be sold on our first trading day in order to fund the tax withholding and remittance obligations arising in connection with the RSUs that will vest and settle upon that day. See the section titled “RSU Sales.” Therefore, there can be no assurance that any Registered Stockholders or other existing stockholders will sell any of their shares of Class A common stock and there may initially be a lack of supply of, or demand for, shares of Class A common stock on the NYSE. Alternatively, we may have a large number of Registered Stockholders or other existing stockholders, including holders of RSUs that vest and settle on the first day of trading, who choose to sell their shares of Class A common stock in the near term, resulting in potential oversupply of our Class A common stock, which could adversely impact the public price of our Class A common stock once listed on the NYSE.

• None of our Registered Stockholders or other existing stockholders have entered into contractual lock-up agreements or other contractual restrictions on transfer. In an underwritten initial public offering, it is customary for an issuer’s officers, directors, and most or all of its other stockholders to enter into a 180-day contractual lock-up arrangement with the underwriters to help promote orderly trading immediately after such initial public offering. Consequently, any of our stockholders, including our directors and officers who own our common stock and other significant stockholders, may sell any or all of their shares of Class A common stock at any time upon conversion of any shares of Class B common stock into Class A common stock at the time of sale (subject to any restrictions under applicable law), including immediately upon listing. If such sales were to occur in a significant volume in a short period of time following the listing, it may result in an oversupply of our Class A common stock in the market, which could adversely impact the public price of our Class A common stock. See also “—None of our stockholders are party to any contractual lock-up agreement or other contractual restrictions on transfer. Following our listing, sales of substantial amounts of our Class A common stock in the public markets or the perception that sales might occur, could cause the market price of our Class A common stock to decline.”

• We will not conduct a traditional “roadshow” with underwriters prior to the opening of trading of our Class A common stock on the NYSE. Instead, we intend to host an investor day and engage in certain other investor education meetings. In advance of the investor day, we will announce the date for such day over financial news outlets in a manner consistent with typical corporate outreach to investors. We intend to prepare an electronic presentation for this investor day, which will have content similar to a traditional roadshow presentation, and to make the presentation publicly available, without restrictions, on our website. There can be no guarantee that the investor day and other investor education meetings will have the same impact on investor education as a traditional “roadshow” conducted in connection with an underwritten initial public offering. As a result, there may not be efficient or sufficient price discovery with respect to our Class A common stock or sufficient demand among potential investors immediately after our listing, which could result in a more volatile public price of our Class A common stock.

• Such differences from an underwritten initial public offering could result in a volatile market price for our Class A common stock and uncertain trading volume, which may adversely affect your ability to sell any Class A common stock that you may purchase.

• We have agreed to indemnify the Registered Stockholders for certain claims arising in connection with sales under this prospectus. Large indemnity payments could adversely affect our business, results of operations, and financial condition.

The public price of our Class A common stock may be volatile, and could, upon listing on the NYSE, decline significantly and rapidly.

The listing of our Class A common stock and the registration of the Registered Stockholders’ shares of Class A common stock is a novel process that is not an underwritten initial public offering. We have engaged Goldman Sachs & Co. LLC, or Goldman Sachs; Morgan Stanley & Co. LLC, or Morgan Stanley; and Allen & Company LLC, or Allen & Company, as our financial advisors. We have also engaged Credit Suisse Securities (USA) LLC, Barclays Capital Inc., Citigroup Global Markets Inc., RBC Capital Markets, LLC, KeyBanc Capital Markets Inc., Canaccord Genuity

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LLC, and William Blair & Company, L.L.C. as our associate financial advisors. There will be no book building process and no price at which underwriters initially sold shares to the public to help inform efficient and sufficient price discovery with respect to the opening trades on the NYSE. As there has not been a recent sustained history of trading in our common stock in a private placement market prior to listing, NYSE listing rules require that a designated marker maker, or DMM, consult with our financial advisors in order to effect a fair and orderly opening of our Class A common stock without coordination with us, consistent with the federal securities laws in connection with our direct listing. Accordingly, Morgan Stanley and our other financial advisors will be available to consult with the DMM who will be setting the opening public price of our Class A common stock on the NYSE. Our financial advisors are expected to provide input to the DMM regarding their understanding of the ownership of our outstanding common stock and pre-listing selling and buying interest in our Class A common stock that they become aware of from potential investors and holders of our Class A common stock, including after consultation with certain institutional investors (which may include certain of the Registered Holders, other than the RSU holders), in each case, without coordination with us. The DMM, in consultation with Morgan Stanley and our other financial advisors, is also expected to consider the information in the section titled “Sale Price History of our Capital Stock.” Based on information provided to the NYSE, the opening public price of our Class A common stock on the NYSE will be determined by buy and sell orders collected by the NYSE from broker-dealers, and the NYSE is where buy orders can be matched with sell orders at a single price. Based on such orders, the DMM will determine an opening price for our Class A common stock pursuant to NYSE rules. However, because our financial advisors will not have engaged in a book building process, they will not be able to provide input to the DMM that is based on or informed by that process. For more information, see the section titled “Plan of Distribution.”

Moreover, prior to the opening trade, there will not be a price at which underwriters initially sold shares of Class A common stock to the public as there would be in an underwritten initial public offering. The absence of a predetermined initial public offering price could impact the range of buy and sell orders collected by the NYSE from various broker-dealers. Consequently, upon listing on the NYSE, the public price of our Class A common stock may be more volatile than in an underwritten initial public offering and could decline significantly and rapidly.

Moreover, because of our novel listing process and the broad consumer awareness and brand recognition of Slack, individual investors, retail or otherwise, may have greater influence in setting the opening public price and subsequent public prices of our Class A common stock on the NYSE and may participate more in our initial trading than is typical for an underwritten initial public offering. These factors could result in a public price of our Class A common stock that is higher than other investors (such as institutional investors) are willing to pay, which could cause volatility in the trading price of our Class A common stock and an unsustainable trading price if the price of our Class A common stock significantly rises upon listing and institutional investors believe our Class A common stock is worth less than retail investors, in which case the price of our Class A common stock may decline over time. Further, if the public price of our Class A common stock is above the level that investors determine is reasonable for our Class A common stock, some investors may attempt to short our Class A common stock after trading begins, which would create additional downward pressure on the public price of our Class A common stock. To the extent that there is a lack of consumer awareness among retail investors, such lack of consumer awareness could reduce the value of our Class A common stock and cause volatility in the trading price of our Class A common stock.

The public price of our Class A common stock following the listing also could be subject to wide fluctuations in response to the risk factors described in this prospectus and others beyond our control, including:

• the number of shares of our Class A common stock publicly owned and available for trading;

• overall performance of the equity markets and/or publicly-listed technology companies;

• actual or anticipated fluctuations in our revenue or other operating metrics;

• our actual or anticipated operating performance and the operating performance of our competitors;

• changes in the financial projections we provide to the public or our failure to meet these projections;

• failure of securities analysts to initiate or maintain coverage of us, changes in financial estimates by any securities analysts who follow our company, or our failure to meet the estimates or the expectations of investors;

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• any major change in our board of directors, management, or key personnel;

• the economy as a whole and market conditions in our industry;

• rumors and market speculation involving us or other companies in our industry;

• announcements by us or our competitors of significant innovations, new products, services, features, integrations or capabilities, acquisitions, strategic investments, partnerships, joint ventures, or capital commitments;

• new laws or regulations or new interpretations of existing laws or regulations applicable to our business, including those related to data privacy and cyber security in the U.S. or globally;

• lawsuits threatened or filed against us;

• other events or factors, including those resulting from war, incidents of terrorism, or responses to these events; and

• sales or expected sales of our Class A common stock by us, and our officers, directors, and principal stockholders.

In addition, stock markets, and the market for technology companies in particular, have experienced price and volume fluctuations that have affected and continue to affect the market prices of equity securities of many companies. Stock prices of many companies, including technology companies, have fluctuated in a manner often unrelated to the operating performance of those companies. These fluctuations may be even more pronounced in the trading market for our Class A common stock shortly following the listing of our Class A common stock on the NYSE as a result of the supply and demand forces described above. In the past, stockholders have instituted securities class action litigation following periods of market volatility. If we were to become involved in securities litigation, it could subject us to substantial costs, divert resources and the attention of management from our business, and harm our business, results of operations, and financial condition.

The public price of our Class A common stock, upon listing on the NYSE, may have little or no relationship to the historical sales prices of our capital stock in private transactions.

Prior to the listing of our Class A common stock on the NYSE, there has been no public market for our capital stock. The historical sales prices of our capital stock is primarily from sales of shares of our Class B common stock (on an as converted basis), which entitle holders to 10 votes per share (as opposed to one vote per share of our Class A common stock). In the section titled “Sale Price History of our Capital Stock,” we have provided the historical sales prices of our capital stock in private transactions. However, given the differences in voting rights between Class A and Class B common stock and the limited history of sales, among other factors, this information may have little or no relation to broader market demand for our Class A common stock and thus the initial public price of our Class A common stock on the NYSE once trading begins. As a result, you should not place undue reliance on these historical sales prices as they may differ materially from the opening public prices and subsequent public prices of our Class A common stock on the NYSE. For more information about how the initial listing price on the NYSE will be determined, see the section titled “Plan of Distribution.”

An active, liquid and orderly market for our Class A common stock may not develop or be sustained. You may be unable to sell your shares of Class A common stock at or above the price you bought them for.

We currently expect our Class A common stock to be listed and traded on the NYSE. Prior to listing on the NYSE, there has been no public market for our common stock. Moreover, consistent with Regulation M and other federal securities laws applicable to our listing, we have not consulted with Registered Stockholders or other existing stockholders regarding their desire or plans to sell shares in the public market following the listing or discussed with potential investors their intentions to buy our Class A common stock in the open market. While our Class A common stock may be sold after our listing on the NYSE by the Registered Stockholders pursuant to this prospectus or by our other existing stockholders in accordance with Rule 144 of the Securities Act of 1933, as amended, or the Securities Act, unlike an underwritten initial public offering, there can be no assurance that any Registered Stockholders or other

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existing stockholders will sell any of their shares of Class A common stock and there may initially be a lack of supply of, or demand for, Class A common stock on the NYSE. Conversely, there can be no assurance that the Registered Stockholders and other existing stockholders will not sell all of their shares of Class A common stock, resulting in an oversupply of our Class A common stock on the NYSE. In the case of a lack of supply of our Class A common stock, the trading price of our Class A common stock may rise to an unsustainable level. Further, institutional investors may be discouraged from purchasing our Class A common stock if they are unable to purchase a block of our Class A common stock in the open market due to a potential unwillingness of our existing stockholders to sell a sufficient amount of Class A common stock at the price offered by such institutional investors and the greater influence individual investors have in setting the trading price. If institutional investors are unable to purchase our Class A common stock, the market for our Class A common stock may be more volatile without the influence of long-term institutional investors holding significant amounts of our Class A common stock. In the case of a lack of demand for our Class A common stock, the trading price of our Class A common stock could decline significantly and rapidly after our listing. Therefore, an active, liquid, and orderly trading market for our Class A common stock may not initially develop or be sustained, which could significantly depress the public price of our Class A common stock and/or result in significant volatility, which could affect your ability to sell your shares of Class A common stock.

The dual class structure of our common stock has the effect of concentrating voting control with those stockholders who held our capital stock prior to the listing of our Class A common stock on the NYSE, including our directors, executive officers and their respective affiliates, who will hold in the aggregate          % of the voting power of our capital stock upon the effectiveness of the registration statement of which this prospectus forms a part. This ownership will limit or preclude your ability to influence corporate matters, including the election of directors, amendments of our organizational documents, and any merger, consolidation, sale of all or substantially all of our assets, or other major corporate transaction requiring stockholder approval.

Our Class B common stock has ten votes per share, and our Class A common stock, which is the stock we are listing on the NYSE and is being registered pursuant to the registration statement of which this prospectus forms a part, has one vote per share. Upon the effectiveness of the registration statement of which this prospectus forms a part, our directors, executive officers and their affiliates will hold in the aggregate          % of the voting power of our capital stock. Because of the ten-to-one voting ratio between our Class B and Class A common stock, the holders of our Class B common stock collectively could continue to control a significant percentage of the combined voting power of our common stock and therefore be able to control all matters submitted to our stockholders for approval until the tenth anniversary of the date of this prospectus, when all outstanding shares of Class A common stock and Class B common stock will convert automatically into shares of a single class of common stock. This concentrated control may limit or preclude your ability to influence corporate matters for the foreseeable future, including the election of directors, amendments of our organizational documents, and any merger, consolidation, sale of all or substantially all of our assets, or other major corporate transaction requiring stockholder approval. In addition, this may prevent or discourage unsolicited acquisition proposals or offers for our capital stock that you may believe are in your best interest as one of our stockholders.

Future transfers by holders of Class B common stock will generally result in those shares converting to Class A common stock, subject to limited exceptions, such as certain transfers effected for estate planning purposes. The conversion of Class B common stock to Class A common stock will have the effect, over time, of increasing the relative voting power of those holders of Class B common stock who retain their shares in the long term. As a result, it is possible that one or more of the persons or entities holding our Class B common stock could gain significant voting control as other holders of Class B common stock sell or otherwise convert their shares into Class A common stock.

In addition, while we do not expect to issue any additional shares of Class B common stock following the listing of our Class A common stock on the NYSE, any future issuances of Class B common stock would be dilutive to holders of Class A common stock.

We cannot predict the effect our dual class structure may have on the market price of our Class A common stock.

We cannot predict whether our dual class structure will result in a lower or more volatile market price of our Class A common stock, in adverse publicity, or other adverse consequences. For example, certain index providers have announced restrictions on including companies with multiple-class share structures in certain of their indices. In July

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2017, FTSE Russell announced that it plans to require new constituents of its indices to have greater than 5% of the company’s voting rights in the hands of public stockholders, and S&P Dow Jones announced that it will no longer admit companies with multiple-class share structures to certain of its indices. Affected indices include the Russell 2000 and the S&P 500, S&P MidCap 400, and S&P SmallCap 600, which together make up the S&P Composite 1500. Also in 2017, MSCI, a leading stock index provider, opened public consultations on their treatment of no-vote and multi-class structures and temporarily barred new multi-class listings from certain of its indices; however, in October 2018, MSCI announced its decision to include equity securities “with unequal voting structures” in its indices and to launch a new index that specifically includes voting rights in its eligibility criteria. Under such announced policies, the dual class structure of our common stock would make us ineligible for inclusion in certain indices and, as a result, mutual funds, exchange-traded funds, and other investment vehicles that attempt to passively track those indices would not invest in our Class A common stock. These policies are relatively new and it is unclear what effect, if any, they will have on the valuations of publicly-traded companies excluded from such indices, but it is possible that they may depress valuations, as compared to similar companies that are included. Because of the dual class structure of our common stock, we will likely be excluded from certain indices and we cannot assure you that other stock indices will not take similar actions. Given the sustained flow of investment funds into passive strategies that seek to track certain indices, exclusion from certain stock indices would likely preclude investment by many of these funds and could make our Class A common stock less attractive to other investors. As a result, the market price of our Class A common stock could be adversely affected.

None of our stockholders are party to any contractual lock-up agreement or other contractual restrictions on transfer. Following our listing, sales of substantial amounts of our Class A common stock in the public markets or the perception that sales might occur, could cause the market price of our Class A common stock to decline.

In addition to the supply and demand and volatility factors discussed above, sales of a substantial number of shares of our Class A common stock into the public market, particularly sales by our directors, executive officers and principal stockholders, or the perception that these sales might occur in large quantities, could cause the market price of our Class A common stock to decline.

As of          , 2019, giving effect to the conversion of all outstanding shares of our convertible preferred stock to shares of Class B common stock upon the effectiveness of the registration statement of which this prospectus forms a part, we have          shares of common stock outstanding, of which          are Class A common stock and          are Class B common stock, all of which will be “restricted securities” (as defined in Rule 144 under the Securities Act). These shares may be immediately sold either by the Registered Stockholders pursuant to this prospectus or by our other existing stockholders under Rule 144 since such shares held by such other stockholders will have been beneficially owned by non-affiliates for at least one year. Moreover, once we have been a reporting company subject to the reporting requirements of Section 13 or Section 15(d) of the Exchange Act for 90 days and assuming the availability of certain public information about us, (i) non-affiliates who have beneficially owned our common stock for at least six months may rely on Rule 144 to sell their shares of common stock, and (ii) our directors, executive officers, and other affiliates who have beneficially owned our common stock for at least six months, including certain of the shares of Class A common stock covered by this prospectus to the extent not sold hereunder, will be entitled to sell their shares our common stock subject to volume limitations under Rule 144 under the Securities Act and various vesting agreements.

Further, as of January 31, 2019, we had 18,405,776 options outstanding that, if fully exercised, would result in the issuance of shares of Class B common stock, as well as 63,113,635 shares of Class B common stock subject to RSU awards. All of the shares of Class B common stock issuable upon the exercise of stock options, subject to RSU awards and reserved for future issuance under our equity incentive plans, will be registered for public resale under the Securities Act. Accordingly, these shares will be able to be freely sold in the public market upon issuance, subject to applicable vesting requirements and compliance by affiliates with Rule 144. The listing and public trading of our Class A common stock on the NYSE will satisfy the performance vesting condition on our RSUs and result in the vesting and settlement of approximately               RSUs held by our current and former employees and other service providers. We expect approximately               shares of our Class A common stock to be sold on our first trading day in order to fund the tax withholding and remittance obligations arising in connection with the RSUs that will vest and settle upon that day and the remaining approximately          shares upon the vesting and settlement of RSUs may also be sold as early as the first day of trading. See the section titled “RSU Sales.” If the market price of our Class A common stock on the NYSE is volatile or if there is an oversupply of shares of Class A common stock and holders of RSUs are unable to sell their

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shares, holders of RSUs would still be responsible for funding the tax withholding and remittance obligations arising in connection with the vesting and settlement of their RSUs and could have to fund such amounts with cash. A potential oversupply of shares due to sales by holders of RSUs could also adversely impact the public price of our Class A common stock.

None of our stockholders are subject to any contractual lock-up or other contractual restriction on the transfer or sale of their shares.

Following the effectiveness of the registration statement of which this prospectus forms a part, the holders of 372,136,712 shares of our Class B common stock will have rights, subject to some conditions, to require us to file registration statements for the public resale of the Class A common stock issuable upon conversion of such shares or to include such shares in registration statements that we may file for us or other stockholders. Any registration statement we file to register additional shares, whether as a result of registration rights or otherwise, could cause the market price of our Class A common stock to decline or be volatile.

We also may issue our capital stock or securities convertible into our capital stock from time to time in connection with a financing, acquisition, investments, or otherwise. Any such issuance could result in substantial dilution to our existing stockholders and cause the public price of our Class A common stock to decline.

The requirements of being a public company may strain our resources, divert management’s attention, and affect our ability to attract and retain executive management and qualified board members.

As a public company, we will be subject to the reporting requirements of the Exchange Act, the listing standards of the NYSE, and other applicable securities rules and regulations. We expect that the requirements of these rules and regulations will continue to increase our legal, accounting, and financial compliance costs, make some activities more difficult, time-consuming, and costly, and place significant strain on our personnel, systems, and resources. For example, the Exchange Act requires, among other things, that we file annual, quarterly, and current reports with respect to our business and results of operations. As a result of the complexity involved in complying with the rules and regulations applicable to public companies, our management’s attention may be diverted from other business concerns, which could harm our business, results of operations, and financial condition. Although we have already hired additional employees to assist us in complying with these requirements, we may need to hire more employees in the future or engage outside consultants, which will increase our operating expenses.

In addition, changing laws, regulations, and standards relating to corporate governance and public disclosure are creating uncertainty for public companies, increasing legal and financial compliance costs, and making some activities more time-consuming. These laws, regulations, and standards are subject to varying interpretations, in many cases due to their lack of specificity, and, as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies. This could result in continuing uncertainty regarding compliance matters and higher costs necessitated by ongoing revisions to disclosure and governance practices. We intend to invest substantial resources to comply with evolving laws, regulations, and standards, and this investment may result in increased general and administrative expenses and a diversion of management’s time and attention from business operations to compliance activities. If our efforts to comply with new laws, regulations and standards differ from the activities intended by regulatory or governing bodies due to ambiguities related to their application and practice, regulatory authorities may initiate legal proceedings against us and our business may be harmed.

We also expect that being a public company and these new rules and regulations will make it more expensive for us to obtain director and officer liability insurance, and we may be required to accept reduced coverage or incur substantially higher costs to obtain coverage. These factors could also make it more difficult for us to attract and retain qualified members of our board of directors, particularly to serve on our audit and risk committee and compensation committee, and qualified executive officers.

As a result of disclosure of information in this prospectus and in filings required of a public company, our business and financial condition will become more visible, which may result in an increased risk of threatened or actual litigation, including by competitors and other third parties. If such claims are successful, our business, results of operations, and financial condition could be harmed, and even if the claims do not result in litigation or are resolved in our favor, these

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claims, and the time and resources necessary to resolve them, could divert the resources of our management and harm our business, results of operations, and financial condition.

If securities or industry analysts do not publish research, or publish inaccurate or unfavorable research, about our business, the price of our Class A common stock and trading volume could decline.

The trading market for our Class A common stock will depend in part on the research and reports that securities or industry analysts publish about us and/or our business. Securities and industry analysts do not currently, and may never, publish research on our company. If few securities analysts commence coverage of us, or if industry analysts cease coverage of us, the trading price for our Class A common stock would be negatively affected. If one or more of the analysts who cover us downgrade our Class A common stock or publish inaccurate or unfavorable research about our business, our Class A common stock price would likely decline. If one or more of these analysts cease coverage of us or fail to publish reports on us on a regular basis, demand for our Class A common stock could decrease, which might cause our Class A common stock price and trading volume to decline.

We do not intend to pay dividends for the foreseeable future.

We have never declared or paid any cash dividends on our common stock and do not intend to pay any cash dividends in the foreseeable future. We anticipate that we will retain all of our future earnings for use in the operation of our business and for general corporate purposes. Any determination to pay dividends in the future will be at the discretion of our board of directors. Accordingly, investors must rely on sales of their Class A common stock after price appreciation, which may never occur, as the only way to realize any future gains on their investments.

Provisions in our charter documents and under Delaware law could make an acquisition of our company more difficult, limit attempts by our stockholders to replace or remove our current board of directors, and limit the market price of our Class A common stock.

Provisions in our amended and restated certificate of incorporation and amended and restated bylaws may have the effect of delaying or preventing a change of control or changes in our management. Our amended and restated certificate of incorporation and amended and restated bylaws, which will become effective shortly following the effectiveness of the registration statement of which this prospectus forms a part, include provisions that:

• provide that our board of directors will be classified into three classes of directors with staggered three-year terms;

• permit our board of directors to establish the number of directors and fill any vacancies and newly-created directorships;

• require super-majority voting to amend some provisions in our amended and restated certificate of incorporation and amended and restated bylaws;

• authorize the issuance of “blank check” preferred stock that our board of directors could use to implement a stockholder rights plan;

• provide that only the Chairperson of our board of directors, our Chief Executive Officer, or a majority of our board of directors will be authorized to call a special meeting of stockholders;

• provide for a dual class common stock structure in which holders of our Class B common stock have the ability to control the outcome of matters requiring stockholder approval, even if they own significantly less than a majority of the outstanding shares of our Class A and Class B common stock, including the election of directors and significant corporate transactions, such as a merger or other sale of our company or its assets;

• prohibit stockholder action by written consent, which requires all stockholder actions to be taken at a meeting of our stockholders;

• provide that the board of directors is expressly authorized to make, alter or repeal our bylaws; and

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• advance notice requirements for nominations for election to our board of directors or for proposing matters that can be acted upon by stockholders at annual stockholder meetings.

Moreover, Section 203 of the Delaware General Corporation Law may discourage, delay, or prevent a change in control of our company. Section 203 imposes certain restrictions on mergers, business combinations, and other transactions between us and holders of 15% or more of our common stock. See the section titled “Description of Capital Stock” for additional information.

Our amended and restated bylaws will designate a state or federal court located within the State of Delaware as the exclusive forum for certain litigation that may be initiated by our stockholders, which could limit stockholders’ ability to obtain a favorable judicial forum for disputes with us.

Our amended and restated bylaws will provide that, to the fullest extent permitted by law, the Court of Chancery of the State of Delaware (or, if the Court of Chancery does not have jurisdiction, the federal district court for the District of Delaware) will be the exclusive forum for:

• any derivative action or proceeding brought on our behalf;

• any action asserting a breach of fiduciary duty;

• any action asserting a claim against us arising pursuant to the Delaware General Corporation Law, our amended and restated certificate of incorporation, or our amended and restated bylaws; or

• or any action asserting a claim against us that is governed by the internal affairs doctrine.

Nothing in our amended and restated bylaws will preclude stockholders that assert claims under the Securities Act from bringing such claims in state or federal court, subject to applicable law.

These choice of forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or any of our directors, officers, or other employees, which may discourage lawsuits with respect to such claims. Alternatively, if a court were to find either choice of forum provision contained in our amended and restated bylaws to be inapplicable or unenforceable in an action, we may incur additional costs associated with resolving such action in other jurisdictions, which could harm our business, results of operations, and financial condition.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains forward-looking statements within the meaning of the federal securities laws, which are statements that involve substantial risks and uncertainties. Forward-looking statements generally relate to future events or our future financial or operating performance. In some cases, you can identify forward-looking statements because they contain words such as “may,” “will,” “shall,” “should,” “expects,” “plans,” “anticipates,” “could,” “intends,” “target,” “projects,” “contemplates,” “believes,” “estimates,” “predicts,” “potential,” or “continue” or the negative of these words or other similar terms or expressions that concern our expectations, strategy, plans, or intentions. Forward-looking statements contained in this prospectus include, but are not limited to, statements about:

• our future financial performance, including our revenue, cost of revenue, and operating expenses;

• our ability to maintain the security and availability of Slack;

• our ability to increase the number of organizations on Slack and paid customers;

• our ability to grow or maintain our Net Dollar Retention Rate;

• our ability to achieve widespread adoption;

• our ability to effectively manage our growth and future expenses;

• our ability to maintain our network of partners;

• our ability to enhance Slack to respond to new technologies and requirements of organizations on Slack;

• our estimated market opportunity;

• the future benefits to be derived from new third-party applications and integrations;

• our ability to maintain, protect, and enhance our intellectual property;

• our ability to comply with modified or new laws and regulations applying to our business;

• the attraction and retention of qualified employees and key personnel;

• our anticipated investments in sales and marketing and research and development;

• the sufficiency of our cash, cash equivalents, and investments to meet our liquidity needs;

• our ability to successfully defend litigation brought against us; and

• the increased expenses associated with being a public company.

We caution you that the foregoing list may not contain all of the forward-looking statements made in this prospectus.

You should not rely upon forward-looking statements as predictions of future events. We have based the forward-looking statements contained in this prospectus primarily on our current expectations and projections about future events and trends that we believe may affect our business, financial condition, results of operations, and prospects. The outcome of the events described in these forward-looking statements is subject to risks, uncertainties, and other factors described in the section titled “Risk Factors” and elsewhere in this prospectus. Moreover, we operate in a very competitive and rapidly changing environment. New risks and uncertainties emerge from time to time, and it is not possible for us to predict all risks and uncertainties that could have an impact on the forward-looking statements contained in this prospectus. The results, events, and circumstances reflected in the forward-looking statements may not be achieved or occur, and actual results, events, or circumstances could differ materially from those described in the forward-looking statements.

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The forward-looking statements made in this prospectus relate only to events as of the date on which the statements are made. We undertake no obligation to update any forward-looking statements made in this prospectus to reflect events or circumstances after the date of this prospectus or to reflect new information or the occurrence of unanticipated events, except as required by law. We may not actually achieve the plans, intentions, or expectations disclosed in our forward-looking statements and you should not place undue reliance on our forward-looking statements. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures, or investments we may make.

In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this prospectus, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain and you are cautioned not to unduly rely upon these statements.

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MARKET AND INDUSTRY DATA

This prospectus contains statistical data and estimates that are based on independent industry publications or other publicly available information, as well as other information based on our internal sources. This information involves a number of assumptions and limitations, and you are cautioned not to give undue weight to these estimates. The industry in which we operate is subject to a high degree of uncertainty and risk due to a variety of factors, including those described in the section titled “Risk Factors.”

Certain information in this prospectus is taken from an independent industry publication (Netskope, Inc., Cloud Report, February 2018) and publicly-available reports.

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USE OF PROCEEDS

Registered Stockholders may, or may not, elect to sell shares of our Class A common stock covered by this prospectus. To the extent any Registered Stockholder chooses to sell shares of our Class A common stock covered by this prospectus, we will not receive any proceeds from any such sales of our Class A common stock. See the section titled “Principal and Registered Stockholders.”

RSU SALES

We grant RSUs to our employees and directors with both service-based and performance vesting conditions. The service-based vesting period for these awards is typically four years with a cliff vesting period of one year and continued vesting quarterly thereafter. The performance vesting condition is satisfied on the earlier of (i) a change in control of the company, (ii) the initial public offering of our securities, or (iii) the listing and public trading of our Class A common stock on the NYSE.

The listing and public trading of our Class A common stock on the NYSE will satisfy the performance vesting condition and result in the vesting and settlement of approximately RSUs held by our current and former employees and other service providers. To fund the personal tax withholding and remittance obligations arising in connection with the RSUs that will vest and settle on that day, we expect that current and former employees will use a broker or brokers to sell a portion of such shares into the market on the first trading day. The proceeds of such sales will be remitted either to us or directly to the relevant taxing authorities, in either case, to be applied towards such tax obligations. Approximately shares of our Class A common stock are expected to be sold throughout the first trading day in order to fund such tax amounts. The number of shares expected to be sold has been calculated using a percentage that is based on the estimated withholding tax rates for those current and former employees and other service providers holding RSUs that will vest and settle on the first trading day. In addition, the estimated number of shares expected to be sold is further based on the estimated weighted-average price for the shares of Class A common stock on the first day of trading on the NYSE, and because that price will not be known until trading closes, the price per share for purposes of this estimate has been based solely on our latest common stock price as determined by our most recently completed independent common stock valuation report, dated as of May 15, 2019, which was $ per share of Class A common stock. One day prior to the commencement of trading on the NYSE, we will recalculate the estimated number of shares expected to be sold based on the NYSE’s published reference price.

In order to meet our obligation to remit withholding taxes on behalf of certain of our employees and former employees on a timely basis, we may use our own cash reserves to satisfy such tax remittance obligations prior to receiving the proceeds from such market sales. We do not currently know the amount of cash that would be used to satisfy these tax withholding obligations because it would be dependent on a number of factors, including the share price at the time of settlement. After the first trading day, additional RSUs typically will vest and settle on the first of each month and RSU holders may sell a portion of such shares into the market.

If the market price of our Class A common stock on the NYSE is volatile or if there is an oversupply of shares of Class A common stock and holders of RSUs are unable to sell their shares, holders of RSUs would still be responsible for funding the tax withholding and remittance obligations arising in connection with the vesting and settlement of their RSUs and could have to fund such amounts with cash.

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DIVIDEND POLICY

We have never declared or paid any cash dividends on our capital stock. We currently intend to retain any future earnings and do not expect to pay any dividends in the foreseeable future. Any future determination to declare cash dividends will be made at the discretion of our board of directors, subject to applicable laws, and will depend on a number of factors, including our financial condition, results of operations, capital requirements, contractual restrictions, general business conditions, and other factors that our board of directors may deem relevant.

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CAPITALIZATION

The following table sets forth cash, cash equivalents, and marketable securities, as well as our capitalization, as of January 31, 2019 as follows:

• on an actual basis; and

• on a pro forma basis, giving effect to (i) the automatic conversion of all outstanding shares of our convertible preferred stock into an aggregate of 373,371,712 shares of our Class B common stock, as if such conversion had occurred on January 31, 2019, (ii) the vesting and settlement of22,388,531RSUs for which the service-based condition was fully satisfied as of January 31, 2019 and for which we expect the performance vesting condition to be satisfied upon the listing and public trading of our Class A common stock on the NYSE, and (iii) stock-based compensation of $157.5 million associated with outstanding RSUs as of January 31, 2019 for which we expect the performance vesting condition to be satisfied upon the listing and public trading of our Class A common stock on the NYSE.

You should read this table together with our consolidated financial statements and related notes, and the sections titled “Selected Consolidated Financial Data and Other Data” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” that are included elsewhere in this prospectus.

	As of January 31, 2019
	Actual			Pro Forma(1)
	(In thousands, except share and per share data)
Cash, cash equivalents, and marketable securities	$	841,071		$	841,071
Stockholders’ equity:
Convertible preferred stock, $0.0001 par value; 390,588,630 shares authorized, 373,371,712 shares issued and outstanding, actual; no shares authorized, issued and outstanding, pro forma	$	1,392,101		—
Class A common stock, $0.0001 par value; 660,000,000 shares authorized, 896,057 shares issued and outstanding, actual; 660,000,000 shares authorized, 896,057 shares issued and outstanding, pro forma	—			—
Class B common stock, $0.0001 par value; 650,000,000 shares authorized, 126,677,232 shares issued and outstanding, actual; 650,000,000 shares authorized, 522,437,475 shares issued and outstanding, pro forma	13			52
Additional paid-in capital	105,633			1,655,190
Accumulated other comprehensive loss	(498		)	(498		)
Accumulated deficit	(665,563		)	(823,058		)
Total Slack Technologies, Inc. stockholders’ equity	831,686			831,686
Noncontrolling interest	9,920			9,920
Total stockholders’ equity	841,606			841,606
Total capitalization	$	841,606		$	841,606

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(1) Payroll taxes and other withholding obligations have not been included in the pro forma column. For additional information, see Note 1 to our consolidated financial statements included elsewhere in this prospectus and the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Significant Impacts of Stock-Based Compensation.”

The pro forma column in the table above is based on 896,057 shares of Class A and 522,437,475 shares of Class B common stock outstanding as of January 31, 2019, and excludes:

• 18,405,776 shares of our Class B common stock issuable upon the exercise of options to purchase shares of our Class B common stock that were outstanding as of January 31, 2019, with a weighted-average exercise price of $0.94 per share;

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• 3,662,500 shares of our Class B common stock issuable upon the vesting and exercise of options to purchase shares of our Class B common stock that were granted after January 31, 2019, with a weighted-average exercise price of $10.58 per share;

• 40,725,104 RSUs for shares of our Class B common stock that are releasable upon satisfaction of service and performance conditions outstanding as of January 31, 2019, for which the service-based condition was not yet satisfied as of January 31, 2019;

• 15,655,394 RSUs for shares of our Class B common stock that are releasable upon satisfaction of service and performance conditions that were granted after January 31, 2019;

• 505,000 restricted stock awards, or RSAs, for shares of our Class B common stock that were granted after January 31, 2019;

• 1,200,000 shares of our Class B common stock reserved for issuance to fund and support our social impact initiatives;

• 7,902,187 shares of our Class B common stock reserved for future issuance pursuant to our 2009 Stock Plan, or our 2009 Plan; and

• 69,200,000 shares of our Class A common stock reserved for future issuance under our stock-based compensation plans to be adopted in connection with the effectiveness of the registration statement of which this prospectus forms a part, consisting of:

• 60,200,000 shares of our Class A common stock reserved for future issuance under our 2019 Stock Option and Incentive Plan, or our 2019 Plan; and

• 9,000,000 shares of our Class A common stock reserved for future issuance under our 2019 Employee Stock Purchase Plan, or ESPP.

Our 2019 Plan and ESPP each provide for annual automatic increases in the number of shares reserved thereunder and our 2019 Plan also provides for increases to the number of shares of Class A common stock that may be granted thereunder based on shares underlying any awards under our 2009 Plan that expire, are forfeited, or are otherwise terminated, as more fully described in the section titled “Executive Compensation—Employee Benefits and Stock Plans.”

Except as otherwise indicated, all information in this prospectus assumes:

• the filing and effectiveness of our amended and restated certificate of incorporation in Delaware and the adoption of our amended and restated bylaws, each of which will occur shortly following the effectiveness of the registration statement of which this prospectus forms a part; and

• the automatic conversion of all outstanding shares of our convertible preferred stock into an aggregate of 373,371,712 shares of our Class B common stock, the conversion of which will occur upon the effectiveness of the registration statement of which this prospectus forms a part.

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SELECTED CONSOLIDATED FINANCIAL DATA AND OTHER DATA

The following selected consolidated statements of operations data for the years ended January 31, 2017, 2018, and 2019 and consolidated balance sheet data as of January 31, 2018 and 2019 have been derived from our audited consolidated financial statements included elsewhere in this prospectus. Our historical results are not necessarily indicative of the results that may be expected in the future. You should read the following selected consolidated financial data and other data below in conjunction with the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our consolidated financial statements and related notes included elsewhere in this prospectus.

	Year Ended January 31,
	2017			2018			2019
	(In thousands, except per share data)
Consolidated Statements of Operations Data:
Revenue	$	105,153		$	220,544		$	400,552
Cost of revenue(1)	15,517			26,364			51,301
Gross profit	89,636			194,180			349,251
Operating expenses:
Research and development(1)	96,678			141,350			157,538
Sales and marketing(1)	104,006			140,188			233,191
General and administrative(1)	37,455			56,493			112,730
Total operating expenses	238,139			338,031			503,459
Loss from operations	(148,503		)	(143,851		)	(154,208		)
Other income (expense), net	1,749			4,581			16,146
Loss before income taxes	(146,754		)	(139,270		)	(138,062		)
Provision for income taxes	155			793			840
Net loss	(146,909		)	(140,063		)	(138,902		)
Net income (loss) attributable to noncontrolling interest(2)	(45		)	22			1,781
Net loss attributable to Slack	(146,864		)	(140,085		)	(140,683		)
Less: Deemed dividends to preferred stockholders	—			40,883			—
Net loss attributable to Slack common stockholders	$	(146,864	)	$	(180,968	)	$	(140,683	)
Basic and diluted net loss per share:
Net loss per share attributable to Slack common stockholders, basic and diluted(3)	$	(1.28	)	$	(1.47	)	$	(1.16	)
Weighted-average shares used in computing net loss per share attributable to Slack common stockholders, basic and diluted(3)	114,887			122,865			121,732
Pro forma net loss per share attributable to Slack common stockholders, basic and diluted (unaudited)(3)							$	(0.27	)
Weighted-average shares used in computing pro forma net loss per share attributable to Slack common stockholders, basic and diluted (unaudited)(3)							517,493

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(1) Includes stock-based compensation as follows:

	Year Ended January 31,
	2017		2018		2019
	(In thousands)
Cost of revenue	$	630	$	491	$	732
Research and development	34,546		35,260		9,948
Sales and marketing	9,744		8,044		2,677
General and administrative	5,171		4,288		9,775
Total stock-based compensation	$	50,091	$	48,083	$	23,132

Stock-based compensation for fiscal years 2017, 2018, and 2019 included compensation expense of $26.5 million, $0, and $14.8 million, respectively, related to secondary sales of common stock by certain of our current and former employees and $8.0 million, $39.4 million, and $0, respectively, related to cash payments attributable to tender offers and repurchases for our outstanding common stock.

(2) Our consolidated financial statements include our majority-owned subsidiary, Slack Fund. The ownership interest of minority investors in Slack Fund is recorded as a noncontrolling interest.

(3) See note 10 to our consolidated financial statements included elsewhere in this prospectus for an explanation of the method used to calculate basic and diluted net loss per share attributable to Slack common stockholders and pro forma basic and diluted net loss per share attributable to Slack common stockholders and the weighted-average number of shares used in the computation of the per share amounts.

	As of January 31,				Pro Forma January 31, 2019(1)
	2018		2019
	(In thousands)
Consolidated Balance Sheet Data:
Cash, cash equivalents, and marketable securities	$	548,761	$	841,071	$	841,071
Working capital	440,258		650,324		650,324
Total assets	697,780		1,198,956		1,198,956
Total deferred revenue	125,453		241,873		241,873
Convertible preferred stock	965,221		1,392,101		—
Total stockholders’ equity	519,288		841,606		841,606

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(1) The pro forma column in the consolidated balance sheet data table above reflects (a) the automatic conversion of all outstanding shares of our convertible preferred stock into 373,371,712 shares of Class B common stock as if such conversion had occurred on January 31, 2019, (b) the vesting and settlement of 22,388,531 RSUs for which the service-based condition was fully satisfied as of January 31, 2019 and for which we expect the performance vesting condition to be satisfied upon the listing and public trading of our Class A common stock on the NYSE, and (c) stock-based compensation of $157.5 million associated with outstanding RSUs as of January 31, 2019 for which we expect the performance vesting condition to be satisfied upon the listing and public trading of our Class A common stock on the NYSE. Payroll taxes and other withholding obligations have not been included in the pro forma column. For additional information, see Note 1 to our consolidated financial statements included elsewhere in this prospectus and in the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Significant Impacts of Stock-Based Compensation.”

Key Business Metrics

We review the following key business metrics to measure our performance, identify trends, formulate financial projections, and make strategic decisions. We are not aware of any uniform standards for calculating these key metrics, which may hinder comparability with other companies who may calculate similarly-titled metrics in a different way.

	As of January 31,
	2017		2018		2019
Paid Customers	37,000		59,000		88,000
Paid Customers >$100,000	135		298		575
Net Dollar Retention Rate	171	%	152	%	143	%

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For additional information about our key business metrics, see the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Key Business Metrics.”

Non-GAAP Financial Measures

In addition to our results determined in accordance with GAAP we believe the below non-GAAP measures are useful in evaluating our operating performance. We use the below non-GAAP financial information, collectively, to evaluate our ongoing operations and for internal planning and forecasting purposes.

	Year Ended January 31,
	2017			2018			2019
	(In thousands)
Calculated Billings	$	143,390		$	289,013		$	516,972
Free Cash Flow	$	(114,038	)	$	(57,661	)	$	(97,239	)
Tender offer payments and repurchases deemed compensation(1)	8,033			39,374			—
Adjusted Free Cash Flow	$	(106,005	)	$	(18,287	)	$	(97,239	)

__________________

(1) In fiscal years 2017 and 2018, we made cash payments of $8.0 million and $39.4 million, respectively, attributable to tender offers and repurchases for our outstanding common stock, which was accounted for as compensation. Adjusted Free Cash Flow has been shown here as adjusted for these cash payments. We have adjusted our Free Cash Flow for these payments because we do not expect them to occur when we are a public company so we believe that this provides greater comparability across periods.

For additional information and reconciliations of the non-GAAP financial measures to the most directly comparable financial measures stated in accordance with GAAP, see the section titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Non-GAAP Financial Measures.”

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MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

You should read the following discussion and analysis of our financial condition and results of operations together with the “Selected Consolidated Financial Data and Other Data” and the consolidated financial statements and related notes included elsewhere in this prospectus. This discussion contains forward-looking statements based upon current expectations that involve risks and uncertainties. Our actual results may differ materially from those anticipated in these forward-looking statements as a result of various factors, including those set forth under the section titled “Risk Factors” or in other parts of this prospectus. Our fiscal year ends January 31.

Overview

Slackis a new layer of the business technology stack that brings together people, applications, and data–a single place where people can effectively work together, access hundreds of thousands of critical applications and services, and find important information to do their best work. Slack has very general and broad applicability. It is not aimed at any one specific purpose, but at nearly anything that people do together at work. Slack is used to review job candidates, coordinate election coverage, diagnose network problems, negotiate budgets, plan marketing campaigns, approve menus, and organize disaster response teams, along with countless other tasks.

Slackprovides an easy way for users to share and aggregate information from other software, take action on notifications, and advance workflows in a multitude of third-party applications, over 1,500 of which are listed in the Slack App Directory. Further, Slack’s platform capabilities extend beyond integrations with third-party applications and allow for easy integrations with an organization’s internally-developed software.

During the three months ended January 31, 2019, our daily active users, which we define as users who either created or consumed content in a given 24-hour period on either a free or paid subscription plan, exceeded 10 million. As of January 31, 2019, Slack had more than 600,000 organizations with three or more users, comprised of more than 88,000 Paid Customers and more than 500,000 organizations on our Free subscription plan. We define an organization as a separate entity, such as a company, educational or government institution, or distinct business unit of a company, that is on a subscription plan, whether free or paid. Once an organization has three or more users on a paid subscription plan, we count them as a Paid Customer.

We serve organizations of all sizes across industries, ranging from software companies, such as Autodesk and Oracle, to consumer retail companies, such as LVMH and Everlane, to financial services companies, such as Liberty Mutual, and government entities, such as NASA Jet Propulsion Laboratory. Slack is currently used in over 150 countries and available in eight languages (English (U.S.), English (U.K.), French, German, Japanese, Portuguese (Brazil), Spanish (Latin America), and Spanish (Spain)). In the years ended January 31, 2017, 2018 and 2019, 34%, 34%, and 36%, respectively, of our revenue was generated by Paid Customers outside of the United States. In the periods presented, no one Paid Customer accounted for more than 3% of our revenue.

We have experienced rapid growth in recent periods. Our revenue was $105.2 million , $220.5 million , and $400.6 million for the years ended January 31, 2017, 2018, and 2019, respectively, representing annual growth of 110% and 82% , respectively. We generated net losses for the years ended January 31, 2017, 2018, and 2019 of $146.9 million , $140.1 million , and $138.9 million , respectively, which included $50.1 million , $48.1 million , and $23.1 million , respectively, of stock-based compensation. Our net losses have been decreasing as a percentage of revenue over time as revenue growth has outpaced the growth in operating expenses. We plan to continue to invest in adding organizations to Slack in order to increase our revenues, decrease our operating losses, and eventually reach profitability. However, there can be no guarantee as to when we will eventually reach profitability, if at all.

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Since our public launch in 2014, we have focused on designing Slack and developing partnerships in ways that have allowed organizations on Slack to realize the value of this new way of working.

Our Subscriptions

We generate revenue primarily from the sale of subscriptions for Slack. Paid customers typically pay on a monthly or annual basis, based on the number of users that they have on Slack. We offer four subscription plans to serve the varying needs of organizations on Slack: Free, Standard, Plus, and Enterprise Grid.

Our Free, Standard, and Plus subscription plans consist of a single workspace, or a basic Slack environment configured for each team. These plans are typically adopted by teams within small- and medium-sized businesses. Our Free subscription plan is designed for new organizations and users to quickly realize value. Our Standard and Plus subscription plans introduce additional capabilities, including enhanced access to content, unlimited integrations, shared channels, guest accounts, and administrative controls. We believe these features offer organizations and users significant value, especially as Slack expands within an organization.

We designed Enterprise Grid for larger organizations that often have tens of thousands of users and require enhanced functionality, flexibility, administrative control, and security at scale. Enterprise Grid allows paid customers to create, manage, and search across an unlimited set of connected workspaces and channels. Enterprise Grid makes it easy for workers and administrators to tap into their organization’s collective knowledge at scale; access centralized controls to provision and manage Slack; and integrate with third-party e-Discovery and data loss prevention tools to help meet security and compliance requirements.

We have a fair billing policy under which certain paid customers are charged a fee per user, and their billing is reconciled on a monthly or quarterly basis based on usage. As part of this policy, these paid customers are entitled to a credit if they have not used the entirety of the contracted number of users for which they have paid during the contractual term of the arrangement. Other paid customers have a type of subscription agreement where they are charged a fee based on the number of purchased user subscriptions, but billing is fixed and independent of usage.

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Our Go-to-Market Model

We combine a web-based, self-service go-to-market approach to attract users with direct sales efforts that focus on growing paid users within larger organizations that generally already have Slack users and acquiring new large organizations as paid customers. We believe that these go-to-market approaches reinforce one another; self-service users become leads for our salespeople and paid users within larger enterprises create organic awareness of Slack inside and outside of their organizations. We complement these activities with an obsessive focus on customer experience and customer success to support the growth of the number of users on free and paid subscriptions.

Self-service adoption and marketing

Many organizations adopt Slack initially as part of our self-service go-to-market approach. We deploy a range of marketing strategies and tactics to drive initial awareness and adoption. Slack is easily accessible from our website and users can immediately begin using Slack through our Free subscription plan. This model facilitates rapid and efficient user adoption, particularly by empowering users to access Slack without the friction of payment or a formal sales interaction. We believe free usage helps prospective paid customers realize the value of Slack and users spread the word organically throughout their networks and organizations. Many of our users begin their journey with Slack on our Free subscription plan.

Our customer experience team is core to enhancing user adoption, free-to-paid conversion, and Net Dollar Retention Rate. This team educates users and organizations on Slack about Slack’s broad use cases and benefits, and helps facilitate broader organic adoption. As organizations engage more deeply with Slack, they often upgrade to paid plans via our website.

Direct sales and marketing

To acquire new paid customers and increase adoption within larger organizations, we utilize a direct sales organization that complements our self-service approach. Our direct sales force leverages Slack champions and proofs of concept developed through self-service adoption. We combine this bottoms-up demand with direct sales efforts targeted at C-suite executives and business unit leaders. These efforts include a globally distributed field sales force, solutions engineering, demand generation campaigns, webinars, analyst relations, C-suite events, cooperative marketing efforts with our partners, and hosted user conferences, highlighted by Frontiers, our annual user conference.

Factors Affecting our Performance

We believe that the growth of Slack and our future success and performance are dependent upon many factors, including those below. While these factors present significant opportunities for us, these factors also represent the challenges that we must successfully address in order to grow the adoption and use of Slack and improve our results of operations.

Self-service acquisition of new organizations

We primarily attract new and prospective organizations organically, through a self-service customer engagement model. Prospective organizations can evaluate and subscribe to Slack directly on our website, through either our Free subscription plan or one of our self-service paid plans. As organizations realize the benefits of Slack, they often expand their usage and spread the word organically throughout their networks about the benefits they have experienced. This organic growth in the number of organizations on Slack in turn leads to increased benefits for organizations already on Slack. We intend to continue investing to maintain organic growth in the number of organizations on Slack by strengthening our efficient self-service customer engagement model and investing in marketing to help new organizations discover the benefits of Slack. This self-service model requires us to incur sales and marketing expenses often prior to generating corresponding revenue.

Conversion of organizations on our free version to paid customers

Many organizations often start using our Free subscription plan. We have observed that organizations on Free subscription plans often upgrade to paid subscriptions as they engage more deeply with Slack, both through using Slack for collaboration and communication and integrating more third-party and internally-developed applications via our

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platform. Often, we believe that organizations on our Free subscription plan convert to a paid subscription plan because of the ability to search and access beyond 10,000 messages, which is the limit under our Free subscription plan, and single-sign-on, which is offered under our Plus plan. In the fiscal year ended January 31, 2018, approximately 10% of our revenue was derived from organizations on our Free subscription plan prior to fiscal year 2018 that converted to Paid Customers in fiscal year 2018. In the fiscal year ended January 31, 2019, approximately 8% of our revenue was derived from organizations on our Free subscription plan prior to fiscal year 2019 that converted to Paid Customers in fiscal year 2019.

We intend to continue to invest in product development, customer experience, customer support, and sales and marketing in order to help all organizations on Slack transform the way they work, which we believe will continue to propel the conversion of organizations on our Free subscription plan to a paid subscription plan.

Success of our direct sales force

We believe that there is a substantial opportunity for us to continue to increase the size of our enterprise paid customer base across a broad range of industries given the fundamental need to help people collaborate, communicate, and seamlessly integrate workflows across applications. Our direct sales force is focused on growing usage within larger paid customers and acquiring new paid customers. We intend to continue to expand our enterprise direct sales force to address this opportunity.

Expansion of users within existing paid customers

We believe that the long-term value of Slack to an organization increases as an organization expands its adoption, increases application integrations, and grows inter- and intra-organization communications. Our direct sales and customer success teams help organizations on Slack realize and achieve the potential value from broader adoption of Slack. We are investing substantially in customer experience, customer success, education, and other capabilities to drive an increase in users within organizations on Slack. We measure the rate of expansion within our Paid Customer base by calculating our Net Dollar Retention Rate. We believe that our Net Dollar Retention Rate demonstrates our large addressable market and high rate of net expansion within Paid Customers. As of January 31, 2019, our Net Dollar Retention Rate was 143%.

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The chart below illustrates the annual recurring revenue, or ARR, of each cohort over the periods presented, with each cohort representing Paid Customers who made their first purchase from us in a given fiscal year. For example, the fiscal year 2015 cohort represents all Paid Customers that purchased their first subscription from us during the fiscal year ended January 31, 2015. For a description of how our ARR is calculated, see the section titled “—Key Business Metrics—Paid Customers >$100,000” below.

Continued investment in product development

We intend to continually invest to innovate and augment Slack’s core capabilities, to further our market leadership and to make Slack an even easier and more effective place where users get work done. For example, we recently launched shared channels, which create a new way for secure inter-organization communication and collaboration beyond what single- and multi-channel guest accounts provide. We also intend to continue investing to expand the number of developers building applications that integrate with Slack and to make Slack work with an increasing number of third-party and internally developed custom applications. We intend to continue to build and enhance Slack through both internal research and development as well as selectively pursuing acquisitions that can uniquely contribute to Slack’s capabilities. We also intend to unlock growth in under-penetrated regions by translating and localizing Slack, as well as adding product functionality to address new markets. We expect these investments to benefit our business over the long term and to see research and development expenses increase in dollar amount over time as we grow.

Continued investment for growth

Although we have invested significantly in our business to date, we believe that our high-growth market opportunity is still in the early stages of development. We intend to continue to make investments to support the growth and expansion of our business, to increase revenue, and to further scale our operations. We believe there is a significant opportunity to continue our growth and, therefore, we intend to increase investments in marketing and expand our field sales team in order to drive greater adoption of Slack. We plan to open offices, hire sales and customer experience employees in additional countries, and expand our presence in countries where we already operate. Further, we expect to incur additional general and administrative expenses in connection with our transition to being a public company. As cost of revenue and operating expenses may fluctuate over time, we may experience short-term, negative impacts to our results of operations and cash flows, but we expect our investments will contribute to the long-term growth and success of our company.

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Key Business Metrics

We review the following key business metrics to measure our performance, identify trends, formulate financial projections, and make strategic decisions. We are not aware of any uniform standards for calculating these key metrics, which may hinder comparability with other companies who may calculate similarly-titled metrics in a different way.

We define an organization as a separate entity, such as a company, educational or government institution, or distinct business unit of a company, that is on a subscription plan, whether free or paid. Once an organization has three or more users on a paid subscription plan, we count them as a Paid Customer, and when disclosing the number of Paid Customers, we round down to the nearest thousand.

	As of January 31,
	2017		2018		2019
Paid Customers	37,000		59,000		88,000
Paid Customers >$100,000	135		298		575
Net Dollar Retention Rate	171	%	152	%	143	%

Paid Customers

We believe that the growth in our Paid Customer base reflects our value proposition and positions us for future growth as our Paid Customers often expand their adoption over time and Paid Customers increase awareness of Slack, which leads to organic adoption by new organizations. Our Paid Customers base has expanded through increasing awareness of Slack, further developing our go-to-market strategy and continuing to build features tuned to different industry needs. Our Paid Customer base includes organizations of all sizes across a wide range of industries.

Paid Customers >$100,000

We focus on growing the number of Paid Customers >$100,000 as a measure of our ability to scale with organizations on Slack and attract larger organizations to Slack. We believe that our ability to increase the number of Paid Customers >$100,000 is a key indicator for important components of the growth of our business, including our success in expanding

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the number of users within a Paid Customer, providing the functionality required by large organizations and developing our direct sales force. In fiscal years 2017, 2018, and 2019, approximately 22%, 32%, and 40%, respectively, of our revenue was generated from our Paid Customers >$100,000.

We define Paid Customers >$100,000 as those organizations on a paid subscription plan that had more than $100,000 in ARR as of a period end. ARR is based on monthly recurring revenue, or MRR, for the most recent month at period end, multiplied by twelve. For Paid Customers that have a type of subscription agreement where billing is reconciled on a monthly or quarterly basis based on usage, MRR is calculated by multiplying the monthly subscription price, inclusive of discounts, by the number of active subscriptions as of the month end. For Paid Customers that have a type of subscription agreement where billing is fixed and independent of usage, MRR is calculated by multiplying the monthly subscription price, inclusive of discounts, by the number of purchased subscriptions.

Net Dollar Retention Rate

We disclose Net Dollar Retention Rate as a supplemental measure of our organic revenue growth. We believe Net Dollar Retention Rate is an important metric that provides insight into the long-term value of our subscription agreements and our ability to retain, and grow revenue from, our Paid Customers.

We calculate Net Dollar Retention Rate as of a period end by starting with the MRR from all Paid Customers as of twelve months prior to such period end, or Prior Period MRR. We then calculate the MRR from these same Paid Customers as of the current period end, or Current Period MRR. Current Period MRR includes expansion within Paid Customers and is net of contraction or attrition over the trailing twelve months, but excludes revenue from new Paid Customers in the current period, including those organizations that were only on Free subscription plans in the prior period and converted to paid subscription plans during the current period. We then divide the total Current Period MRR by the total Prior Period MRR to arrive at our Net Dollar Retention Rate. Our Net Dollar Retention Rate has declined from 171% as of January 31, 2017 to 152% as of January 31, 2018 to 143% as of January 31, 2019 as our base of revenue has grown the past few years and our penetration within existing, long-term Paid Customers has increased. Our Net Dollar Retention Rate will fluctuate in future periods due to a number of factors, including the growing level of our revenue base, the level of penetration within our Paid Customer base, expansion of products and features, and our ability to retain our Paid Customers.

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Non-GAAP Financial Measures

In addition to our results determined in accordance with GAAP, we believe the below non-GAAP measures are useful in evaluating our operating performance. We use the below non-GAAP financial information, collectively, to evaluate our ongoing operations and for internal planning and forecasting purposes. We believe that non-GAAP financial information, when taken collectively, may be helpful to investors because it provides consistency and comparability with past financial performance, and assists in comparisons with other companies, some of which use similar non-GAAP financial information to supplement their GAAP results. The non-GAAP financial information is presented for supplemental informational purposes only, and should not be considered a substitute for financial information presented in accordance with GAAP, and may be different from similarly-titled non-GAAP measures used by other companies. A reconciliation is provided below for each non-GAAP financial measure to the most directly comparable financial measure stated in accordance with GAAP. Investors are encouraged to review the related GAAP financial measures and the reconciliation of these non-GAAP financial measures to their most directly comparable GAAP financial measures.

	Year Ended January 31,
	2017			2018			2019
	(In thousands)
Calculated Billings	$	143,390		$	289,013		$	516,972
Free Cash Flow	$	(114,038	)	$	(57,661	)	$	(97,239	)
Tender offer payments and repurchases deemed compensation(1)	8,033			39,374			—
Adjusted Free Cash Flow	$	(106,005	)	$	(18,287	)	$	(97,239	)

__________________

(1) In fiscal years 2017 and 2018, we made cash payments of $8.0 million and $39.4 million, respectively, attributable to tender offers and repurchases for our outstanding common stock, which was accounted for as compensation. Adjusted Free Cash Flow has been shown here as adjusted for these cash payments. We have adjusted our Free Cash Flow for these payments because we do not expect them to occur when we are a public company so we believe that this provides greater comparability across periods.

Calculated Billings

Calculated Billings consists of our revenue plus the change in our deferred revenue in a given period. The Calculated Billings metric is intended to reflect sales to new paid customers plus renewals and additional sales to existing paid customers. Our management uses Calculated Billings to measure and monitor our sales growth because we generally bill our paid customers at the time of sale, but may recognize a portion of the related revenue ratably over time. For subscriptions, we typically invoice our paid customers at the beginning of the term, in annual or monthly installments and, from time to time, in multi-year installments. Only amounts invoiced to a paid customer in a given period are included in Calculated Billings. While we believe that Calculated Billings provides valuable insight into the cash that will be generated from sales of our subscriptions, this metric may vary from period-to-period for a number of reasons, and therefore has a number of limitations as a quarter-over-quarter or year-over-year comparative measure. These reasons include, but are not limited to, the following: (i) a variety of contractual terms could result in some periods having a higher proportion of annual subscriptions than other periods, (ii) as we focus on sales to large organizations, the lengthening of our sales cycle, and the variability in the timing of the execution of these larger transactions, (iii) fluctuations in payment terms affecting the billings recognized in a particular period, and (iv) seasonality in our billings, with a greater proportion of our billings occurring in our fourth quarter, following typical enterprise software buying patterns. Because of these and other limitations, you should consider Calculated Billings along with revenue and our other GAAP financial results.

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The following table presents a reconciliation of revenue, the most directly comparable financial measure calculated in accordance with GAAP, to Calculated Billings, for each of the periods presented:

	Year Ended January 31,
	2017			2018			2019
	(In thousands)
Revenue	$	105,153		$	220,544		$	400,552
Add: Total deferred revenue, end of period	56,984			125,453			241,873
Less: Total deferred revenue, beginning of period	(18,747		)	(56,984		)	(125,453		)
Calculated Billings	$	143,390		$	289,013		$	516,972

Free Cash Flow and Adjusted Free Cash Flow

Free Cash Flow is a non-GAAP financial measure that we calculate as net cash provided by (used in) operating activities less purchases of property and equipment. Adjusted Free Cash Flow is a non-GAAP financial measure that we calculate as Free Cash Flow plus cash payments attributable to tender offers and repurchases for our outstanding common stock, which was accounted for as compensation. We believe that Free Cash Flow and Adjusted Free Cash Flow are useful indicators of liquidity that provide information to management and investors about the amount of cash generated from our core operations that, after the purchases of property and equipment, can be used for strategic initiatives, including investing in our business, making strategic acquisitions, and strengthening our balance sheet. We have adjusted our Free Cash Flow by the amount of cash payments attributable to tender offers and repurchases, which was accounted for as compensation because we do not expect such payments to occur when we are public company so we believe that this provides greater comparability across periods. Free Cash Flow and Adjusted Free Cash Flow have limitations as analytical tools, and they should not be considered in isolation or as substitutes for analysis of other GAAP financial measures, such as net cash provided by operating activities. Some of the limitations of Free Cash Flow and Adjusted Free Cash Flow are that these metrics do not reflect our future contractual commitments and may be calculated differently by other companies in our industry, limiting their usefulness as comparative measures. We expect our Free Cash Flow and Adjusted Free Cash Flow to fluctuate in future periods as we invest in our business to support our plans for growth. These activities, along with certain increased operating expenses as described below, may result in a decrease in Free Cash Flow and Adjusted Free Cash Flow, each as a percentage of revenue in future periods. We do not expect to use Adjusted Free Cash Flow as a metric for periods after we become a public reporting company.

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The following table summarizes our cash flows for the periods presented and provides a reconciliation of net cash from operating activities, the most directly comparable financial measure calculated in accordance with GAAP, to Free Cash Flow and Adjusted Free Cash Flow, for each of the periods presented:

	Year Ended January 31,
	2017			2018			2019
	(In thousands)
Net cash used in operating activities	$	(89,806	)	$	(35,617	)	$	(41,059	)
Purchases of property and equipment	(24,232		)	(22,044		)	(56,180		)
Free Cash Flow	(114,038		)	(57,661		)	(97,239		)
Tender offer payments and repurchases deemed compensation(1)	8,033			39,374			—
Adjusted Free Cash Flow	$	(106,005	)	$	(18,287	)	$	(97,239	)
Net cash used in investing activities	$	(41,771	)	$	(240,436	)	$	(333,421	)
Net cash provided by financing activities	$	214,096		$	297,035		$	437,677

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(1) In fiscal years 2017 and 2018, we made cash payments of $8.0 million and $39.4 million, respectively, attributable to tender offers and repurchases for our outstanding common stock, which was accounted for as compensation. Adjusted Free Cash Flow has been shown here as adjusted for these cash payments. We have adjusted our Free Cash Flow for these payments because we do not expect them to occur when we are public company so we believe that this provides greater comparability across periods.

Key Components of Results of Operations

Revenue

We generate substantially all of our revenue through sales of subscriptions of Slack to organizations. We recognize subscription revenue on a straight-line basis over the term of the contract subscription period beginning on the date access to Slack is granted, provided all other revenue recognition criteria have been met.Our subscriptions are generally non-cancellable and typically do not contain general rights of return. We maintain a fair billing policy, under which certain organizations on a paid subscription plan are entitled to credit if they have not used the entirety of the contracted number of users for which they have paid during the contractual term of the arrangement. These credits, accounted for as a part of deferred revenue, may be carried over to offset future billings and are not refundable for cash. On occasion, we also provide professional services to organizations on Slack. Professional services revenue has not been material to date.

Overhead Allocation and Employee Compensation Costs

We allocate shared costs, such as facilities (including rent, utilities, and depreciation on equipment shared by all departments) and information technology (IT) costs to all departments based on headcount. As such, allocated shared costs are reflected in cost of revenue and each operating expense category. Employee compensation costs, or personnel costs, include salaries, bonuses, benefits, and stock-based compensation for cost of revenue and each operating expense category and also includes sales commissions for sales and marketing.

Cost of Revenue

Cost of revenue consists primarily of expenses related to hosting Slack and providing ongoing customer support for paid customers. These expenses includeemployee compensation (including stock-based compensation) and other employee-related expenses for customer experience and technical operations staff, payments to outside service providers, third-party hosting costs, payment processing fees, and amortization expense associated with internally-developed and purchased technology. We expect our cost of revenue to continue to increase in absolute dollar amounts as we grow our business and revenue.

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Operating Expenses

Research and Development. Research and development expenses consist primarily of personnel costs and allocated overhead. Our research and development efforts focus on maintaining and enhancing existing functionality of, and adding new functionality to, Slack. We plan to increase the dollar amount of our investment in research and development for the foreseeable future as we focus on developing new features and enhancements. We expect, however, that our research and development expenses will decrease as a percentage of our revenue over time as our revenue grows, although the percentage may fluctuate from period to period depending on fluctuations in the timing and extent of our research and development expenses.

Sales and Marketing. Sales and marketing expenses consist primarily of personnel costs, expenses associated with our marketing and business development programs, including Frontiers, our annual user conference. Sales and marketing expenses also include allocated third-party hosting costs as well as customer experience and technical operations employee overhead costs for users of our free version of Slack. Sales commissions that are directly related to acquiring sales contracts, as well as associated payroll taxes, are deferred upon execution of a non-cancellable contract with an organization, and subsequently amortized to sales and marketing expense over the estimated period of benefit, typically four years. We plan to increase the dollar amount of our investment in sales and marketing for the foreseeable future, primarily for increased headcount for our direct sales organization and investment in brand and product marketing efforts. We expect, however, that our sales and marketing expenses will decrease as a percentage of our revenue over time as our revenue grows, although the percentage may fluctuate from period to period depending on fluctuations in the timing and extent of our sales and marketing expenses.

General and Administrative. General and administrative expenses consist primarily of personnel costs for our finance and accounting, legal, human resources, and other administrative teams as well as for certain executives and professional fees, including audit, legal, and recruiting services. We expect to increase the size of our general and administrative function to support the growth of our business. We also expect to recognize certain non-recurring costs as part of our transition to a publicly-traded company, consisting of professional fees and other expenses. These fees are being expensed in the period incurred. We expect to incur $          million in audit fees and $          million in legal fees and expenses. In the quarter of the listing of our Class A common stock on the NYSE, we expect to incur approximately $          million in fees paid to our financial advisors and associate financial advisors. Following the listing of our Class A common stock on the NYSE, we expect to continue to incur additional expenses as a result of operating as a public company, including costs to comply with the rules and regulations applicable to companies listed on a U.S. securities exchange and costs related to compliance and reporting obligations pursuant to the rules and regulations of the SEC. In addition, as a public company, we expect to incur increased expenses in the areas of insurance, investor relations, and professional services. As a result, we expect the dollar amount of our general and administrative expenses to increase for the foreseeable future. We expect, however, that our general and administrative expenses will decrease as a percentage of our revenues over time, although the percentage may fluctuate from period to period depending on fluctuations in our revenue and the timing and extent of our general and administrative expenses.

Other Income (Expense), Net

Other income (expense), net consists primarily of interest income earned on our cash, cash equivalents, and marketable securities, gains or losses on foreign currency exchange, and the change in fair value of our strategic investments.

Provision for Income Taxes

Provision for income taxes consists primarily of U.S. federal, state income taxes, and income taxes in certain foreign jurisdictions in which we conduct business. Since inception, we have incurred operating losses and, accordingly, have not recorded a provision for income taxes for any of the periods presented other than provisions for foreign income tax. As of January 31, 2019, we had net operating loss carryforwards for both federal and state income tax purposes of $221.4 million and $154.5 million, respectively. We also had federal research and development tax credit carryforwards of approximately $17.2 million and state research and development tax credit carryforwards of approximately $14.4 million.

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Since the realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain, we have recorded a valuation allowance of $112.7 million as of January 31, 2019, against our net deferred tax asset balance of $112.7 million. If not utilized, a portion of the federal and state net operating loss and tax credit carryforwards will begin to expire in 2029. Utilization of these net operating losses and credit carryforwards may be subject to an annual limitation that is applicable if we experience an “ownership change” through a change in significant stockholder allocation or equity structure.

On December 22, 2017, the legislation commonly referred to as the Tax Cuts and Jobs Act, or the Tax Act, was enacted, which contains significant changes to U.S. tax law. Among other provisions, the Tax Act reduces the U.S. corporate income tax rate to 21% and repeals the alternative minimum tax, effective as of 2018. As a result, we have re-measured our U.S. deferred tax assets and liabilities as of December 31, 2017 to reflect the lower rate expected to apply when these temporary differences reverse.

Results of Operations

The following tables set forth our results of operations for the periods presented in dollars and as a percentage of our revenue:

	Year Ended January 31,
	2017			2018			2019
	(In thousands)
Revenue	$	105,153		$	220,544		$	400,552
Cost of revenue(1)	15,517			26,364			51,301
Gross profit	89,636			194,180			349,251
Operating expenses:
Research and development(1)	96,678			141,350			157,538
Sales and marketing(1)	104,006			140,188			233,191
General and administrative(1)	37,455			56,493			112,730
Total operating expenses	238,139			338,031			503,459
Loss from operations	(148,503		)	(143,851		)	(154,208		)
Other income (expense), net	1,749			4,581			16,146
Loss before income taxes	(146,754		)	(139,270		)	(138,062		)
Provision for income taxes	155			793			840
Net loss	(146,909		)	(140,063		)	(138,902		)
Net income (loss) attributable to noncontrolling interest(2)	(45		)	22			1,781
Net loss attributable to Slack	(146,864		)	(140,085		)	(140,683		)
Less: Deemed dividends to preferred stockholders	—			40,883			—
Net loss attributable to Slack common stockholders	$	(146,864	)	$	(180,968	)	$	(140,683	)

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(1) Includes stock-based compensation as follows:

	Year Ended January 31,
	2017		2018		2019
	(In thousands)
Cost of revenue	$	630	$	491	$	732
Research and development	34,546		35,260		9,948
Sales and marketing	9,744		8,044		2,677
General and administrative	5,171		4,288		9,775
Total stock-based compensation	$	50,091	$	48,083	$	23,132

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(2) Our consolidated financial statements include our majority-owned subsidiary, Slack Fund. The ownership interest of minority investors in Slack Fund is recorded as a noncontrolling interest.

	Year Ended January 31,
	2017		2018		2019
	(as a % of revenue)
Revenue	100	%	100	%	100	%
Cost of revenue	15		12		13
Gross profit	85		88		87
Operating expenses:
Research and development	92		64		39
Sales and marketing	99		63		58
General and administrative	35		26		28
Total operating expenses	226		153		125
Loss from operations	(141	)	(65	)	(38	)
Other income (expense), net	1		2		4
Loss before income taxes	(140	)	(63	)	(34	)
Provision for income taxes	—		1		1
Net loss	(140	)	(64	)	(35	)
Net income (loss) attributable to noncontrolling interest	—		—		—
Net loss attributable to Slack	(140	)	(64	)	(35	)
Less: Deemed dividends to preferred stockholders	—		18		—
Net loss attributable to Slack common stockholders	(140	)%	(82	)%	(35	)%

Comparison of the Years Ended January 31, 2018 and 2019

Revenue and Cost of Revenue

Year Ended January 31,
2018	2019	$ Change	% Change
(In thousands)