Registration Statement On Form S-1

As filed with the Securities and Exchange Commission on May 7, 2015

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Fitbit, Inc.

(Exact name of Registrant as specified in its charter)

Delaware 3600 20-8920744 (State or other jurisdiction of incorporation or organization) (Primary Standard Industrial Classification Code Number) (I.R.S. Employer Identification Number)

Fitbit, Inc.

405 Howard Street

San Francisco, California 94105

(415) 513-1000

(Address, including zip code, and telephone number, including area code, of Registrants principal executive offices)

James Park

President and Chief Executive Officer Fitbit, Inc.

405 Howard Street

San Francisco, California 94105

(415) 513-1000

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Cynthia C. Hess, Esq. Jeffrey R. Vetter, Esq. James D. Evans, Esq. Fenwick & West LLP 801 California Street Mountain View, California 94041 (650) 988-8500 Andy Missan, Esq. Vice President and General Counsel Fitbit, Inc. 405 Howard Street San Francisco, California 94105 (415) 513-1000 Rezwan D. Pavri, Esq. Richard A. Kline, Esq. Goodwin Procter LLP 135 Commonwealth Drive Menlo Park, California 94025 (650) 752-3100

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this Registration Statement.

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 of 1933, or Securities Act, check the following box. ¨

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) 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(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, or a smaller reporting company. See definitions of large accelerated filer, accelerated filer, and smaller reporting company in Rule 12b-2 of the Securities Exchange Act of 1934. (Check one):

Large accelerated filer ¨ Accelerated filer ¨ Non-accelerated filer x (Do not check if a smaller reporting company) Smaller reporting company ¨

CALCULATION OF REGISTRATION FEE

Title of Each Class of Securities to be Registered Proposed

Maximum

Aggregate

Offering Price(1)(2) Amount of

Registration Fee Class A common stock, par value $0.0001 per share $100,000,000 $11,620

(1) Estimated solely for the purpose of calculating the amount of the registration fee pursuant to Rule 457(o) under the Securities Act.

(2) Includes the aggregate offering price of additional shares that the underwriters have the option to purchase to cover over-allotments, if any.

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 that specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. Neither we nor the selling stockholders may sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities, and neither we nor the selling stockholders are soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted. PROSPECTUS (Subject to Completion) Issued May 7, 2015 Shares CLASS A COMMON STOCK Fitbit, Inc. is offering shares of its Class A common stock and the selling stockholders are offering shares of Class A common stock. We will not receive any proceeds from the sale of shares by the selling stockholders. This is our initial public offering and no public market currently exists for our shares of Class A common stock. We anticipate that the initial public offering price of our Class A common stock will be between $ and $ per share. We have two classes of common stock, Class A common stock and Class B common stock. The rights of the 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 ten votes and is convertible at any time into one share of Class A common stock. The holders of our outstanding Class B common stock will hold approximately % of the voting power of our outstanding capital stock following this offering, with our directors and executive officers and their affiliates holding approximately %. We intend to apply to list our Class A common stock on the New York Stock Exchange under the symbol FIT. We are an emerging growth company as defined under the federal securities laws. Investing in our Class A common stock involves risks. See the section titled Risk Factors beginning on page 15. PRICE $ A SHARE Price to Public Underwriting

Discounts and

Commissions (1) Proceeds to Fitbit Proceeds to Selling

Stockholders Per share $ $ $ $ Total $ $ $ $ (1) See the section titled Underwriters for a description of the compensation payable to the underwriters. We and the selling stockholders have granted the underwriters the right to purchase up to an additional shares of Class A common stock to cover over-allotments. The Securities and Exchange Commission and state securities regulators have not approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense. The underwriters expect to deliver the shares of Class A common stock to purchasers on , 2015. MORGAN STANLEY DEUTSCHE BANK SECURITIES BofA MERRILL LYNCH BARCLAYS SUNTRUST ROBINSON HUMPHREY PIPER JAFFRAY RAYMOND JAMES STIFEL WILLIAM BLAIR , 2015

TRACK

LEARN

MOTIVATE

DASHBOARD

TRENDS

BADGES

CHALLENGES

Fitbit platform

CONNECTED HEALTH & FITNESS DEVICES

IMPROVE

NOTIFICATIONS

SOCIAL

PREMIUM SERVICES

PERSONALIZED INSIGHTS

VIRTUAL COACHING

TABLE OF CONTENTS

You should rely only on the information contained in this prospectus and in any free writing prospectus prepared by or on behalf of us and delivered or made available to you. Neither we, the selling stockholders, nor any of the underwriters have authorized anyone to provide you with additional or different information. We and the selling stockholders are offering to sell, and seeking offers to buy, shares of our Class A common stock only in jurisdictions where offers and sales are permitted. The information contained in this prospectus or a free writing prospectus is accurate only as of its date, regardless of its time of delivery or of any sale of shares of our Class A common stock. Our business, financial condition, operating results, and prospects may have changed since that date.

Until , 2015 (25 days after commencement of this offering), all dealers that buy, sell, or trade shares of our Class A common stock, whether or not participating in this offering, may be required to deliver a prospectus. This delivery requirement is in addition to the obligation of dealers to deliver a prospectus when acting as underwriters and with respect to their unsold allotments or subscriptions.

For investors outside the United States: Neither we, the selling stockholders, nor any of the underwriters have done anything that would permit this offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside of the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the shares of Class A common stock and the distribution of this prospectus outside of the United States.

i

PROSPECTUS SUMMARY This summary highlights information presented in greater detail elsewhere in this prospectus. This summary is not complete and does not contain all the information you should consider before investing in our Class A common stock. You should read the 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 related notes included elsewhere in this prospectus, before investing in our Class A common stock. FITBIT, INC. Our Mission Fitbit helps people lead healthier, more active lives by empowering them with data, inspiration, and guidance to reach their goals. Overview Fitbit is transforming the way millions of people around the world achieve their health and fitness goals. The Fitbit platform combines connected health and fitness devices with software and services, including an online dashboard and mobile apps, data analytics, motivational and social tools, personalized insights, and virtual coaching through customized fitness plans and interactive workouts. Our platform helps people become more active, exercise more, sleep better, eat smarter, and manage their weight. Fitbit appeals to a large, mainstream health and fitness market by addressing these key needs with advanced technology embedded in simple-to-use products and services. We pioneered the connected health and fitness market starting in 2007, and since then, we have grown into a leading global health and fitness brand. As of March 31, 2015, we have sold over 20.8 million devices since inception. According to The NPD Group, we held the leading position in the U.S. fitness activity tracker market, with a 68% share, by dollars, in 2014. * The core of our platform is our family of six wearable connected health and fitness trackers. These wrist-based and clippable devices automatically track users daily steps, calories burned, distance traveled, floors climbed, and active minutes and display real-time feedback to encourage them to become more active in their daily lives. Most of our trackers also measure sleep duration and quality, and our more advanced products track heart rate and GPS-based information such as speed, distance, and exercise routes. Several of our devices also feature deeper integration with smartphones, such as the ability to receive call and text notifications and control music. In addition, we offer a Wi-Fi connected scale that records weight, body fat, and body mass index, or BMI. We dedicate significant resources to developing proprietary sensors, algorithms, and software to ensure that our products have highly accurate measurements, insightful analytics, compact sizes, durability, and long battery lives. We are able to enhance the functionality and features of our connected devices through wireless updates. Our platform also includes our online dashboard and mobile apps, which wirelessly and automatically sync with our devices. Our platform allows our users to see trends and achievements, access motivational tools such as virtual badges and real-time progress notifications, and connect, support, and compete with friends and family. Our direct connection with our users enables us to provide personalized insights, premium services, and information about new products and services. Premium services include virtual coaching through customized fitness plans and interactive video-based exercise experiences on mobile devices and computers. In addition, we extend the value of our platform through our open application programming interface, or API, which enables third-party developers to create health and fitness apps that interact with our platform. Our open platform and our large community of users, we have established a growing ecosystem that includes thousands of third-party health and fitness apps that connect with our products and enhance the Fitbit experience. * See Industry and Market Data.

1

Our platform enables all types of people to get fit their own way, whatever their interests and goals. Our users range from people interested in improving their health and fitness through everyday activities to endurance athletes seeking to maximize their performance. To address this range of needs, we design our devices, apps, and services to be easy to use so that they fit seamlessly into peoples daily lives or activities. Our users can sync their Fitbit devices with, and view their dashboard on, their computers and over 150 mobile devices, including iOS, Android, and Windows Phone products. This broad compatibility, combined with our market-leading position, has enabled us to attract what we believe is the largest community of connected health and fitness device users. The size of our user community increases the likelihood that our users will be able to find and engage with friends and family, creating positive network effects that reinforce our growth and user retention. In addition, data from our large community enables us to enhance our product features, provide improved insights, and offer more valuable guidance for our users. We have rapidly grown to become a leading global health and fitness brand. We sell our products in over 45,000 retail stores and in more than 50 countries, through our retailers websites, through our online store at Fitbit.com, and as part of our corporate wellness offering. Our broad distribution and market-leading connected health and fitness platform have driven significant growth since our founding. In 2011, 2012, 2013, and 2014, we had revenue of $14.5 million, $76.4 million, $271.1 million, and $745.4 million, respectively, net income (loss) of $(4.3) million, $(4.2) million, $(51.6) million, and $131.8 million, respectively, and adjusted EBITDA of $(4.0) million, $(2.4) million, $79.0 million, and $191.0 million, respectively. For the three months ended March 31, 2014 and 2015, we had revenue of $108.8 million and $336.8 million, respectively, net income of $8.9 million and $48.0 million, respectively, and adjusted EBITDA of $42.0 million and $93.4 million, respectively. See the section titled Selected Consolidated Financial and Other DataAdjusted EBITDA for information regarding our use of adjusted EBITDA and a reconciliation of adjusted EBITDA to net income (loss). The number of devices we sold grew from 0.2 million in 2011, to 1.3 million in 2012, to 4.5 million in 2013, and to 10.9 million in 2014, and from 1.6 million in the three months ended March 31, 2014 to 3.9 million in the three months ended March 31, 2015. We also had 0.6 million, 2.6 million, 6.7 million, and 9.5 million paid active users as of December 31, 2012, 2013, and 2014, and March 31, 2015, respectively. See the section titled Managements Discussion and Analysis of Financial Condition and Results of OperationsKey Business Metrics for additional information regarding devices sold and paid active users.

2

Powerful Trends Driving Our Market Several powerful trends are driving the growth of the connected health and fitness market:  Individuals and employers are increasingly focused on health and fitness. A variety of factors, such as changing consumer lifestyles and demographics, combined with rising healthcare costs and employers increased emphasis on productivity, are leading individuals and employers to increasingly focus on health and fitness. Based on information from industry sources, we estimate consumers spent over $200 billion in 2014 on health and fitness services, such as gym and health club memberships, commercial weight management services, and consumer health products, such as weight management products and dietary supplements. In addition, IBISWorld estimates that the corporate wellness industry will grow from $7.4 billion in 2014 to $10.4 billion in 2018 in the United States. *  Advances in technology have enabled the emergence of connected devices. Recent technological advances in sensors, lower power components, and longer-life batteries, combined with the introduction of wireless standards, such as Bluetooth low energy, have enabled the emergence of connected devices that are smaller, more power-efficient, track a broader range of biometric data, and fit a wide range of consumer preferences.  Mobile devices have become the preferred platform for accessing information. Mobile devices have become the preferred platform for people to access information and manage their lives, as well as the primary hub to connect a variety of consumer devices. According to Gartner, by 2018 more than 50% of users will go to a tablet or smartphone first for all online activities. *  More individuals are turning to technology solutions to improve health and fitness. Individuals are increasingly using mobile apps and other software to improve health and fitness, allowing consumers to directly manage and track their health and fitness in unprecedented ways. According to The NPD Group, over 25% of U.S. consumers reported using a fitness app on their smartphone. * Our Market Opportunity According to International Data Corporation, or IDC, consumer spend on the wearable devices market is growing faster than on any segment in the global consumer electronics market. * In 2014, shipments of wearable * See Industry and Market Data.

3

devices more than tripled compared to the prior year, reaching a total of 21.0 million units shipped. * IDC expects the market for wearable devices will reach 114.0 million units shipped in 2018, representing a $33.7 billion worldwide revenue opportunity. * We believe that we have been one of the drivers of the growth of the wearable devices market, and that the future growth of this market represents a significant opportunity for us. Further, as we continue to expand our platform and as consumers increasingly view our connected health and fitness products and services as an alternative or complement to other health and wellness activities, we believe there is an opportunity to extend our addressable market to the broader health and fitness market. Based on information from industry sources, we estimate this market represents an over $200 billion opportunity and includes consumer spend on health and fitness services, such as gym and health club memberships, commercial weight management services, and consumer health products, such as weight management products and dietary supplements. The broader health and fitness market, however, presents several challenges to overcome before we are able to take advantage of this opportunity, including competition from larger, more established traditional health and fitness companies, uncertainty as to whether consumers will adopt our products and services as an alternative or complement to other health and wellness activities, and our relative lack of experience selling other products and services. Our SolutionThe Fitbit Platform Our leading connected health and fitness platform is designed to enable our users to improve their health and fitness by:  Tracking activities through our connected health and fitness devices. We empower users to live healthier, more active lifestyles by both tracking the information that matters most to them and providing them with real-time feedback. Our connected health and fitness devices span multiple styles, form factors, and price points, addressing the needs of everyonefrom people simply looking to get fit by increasing their activity levels to endurance athletes seeking to maximize their performance.  Learning through our online dashboard and mobile apps. We offer our users a personalized online dashboard and mobile apps that sync automatically with our connected health and fitness devices and provide our users with a wide range of information and analytics, such as charts and graphs of their progress and the ability to log caloric intake.  Staying motivated through social features, notifications, challenges, and virtual badges. Our products help millions of users achieve their goals both individually and within the community that they choose. We motivate users by delivering real-time feedback including notifications, leaderboard and challenge updates, and virtual badges. Users can choose to share some or all of their health and fitness information on an opt-in basis with friends, family, and other parties, with third-party apps, and through social networks.  Improving health and fitness through goal-setting, personalized insights, premium services, and virtual coaching. We believe our platform assists users in changing their daily behavior, such as eating healthier foods or going for a run or walking more to reach a goal or win a challenge. We also offer premium services on a subscription basis that provide personalized insights and virtual coaching through customized fitness plans and interactive video-based exercise experiences on mobile devices and computers. Our Competitive StrengthsWhat Sets Us Apart We believe the following strengths will allow us to maintain and extend our leadership position:  Leading market position and global brand. Our singular focus on building a connected health and fitness platform, coupled with our leading market share, has led to our brand becoming synonymous

4

with the connected health and fitness category. According to The NPD Group, Fitbit devices were the highest selling fitness activity trackers in the United States in 2014, with a 68% share of the U.S. fitness activity tracker market, by dollars, up from 58% in 2013. *  Broad range of connected health and fitness devices. We believe everyones approach to fitness is different, so we offer our users a range of connected health and fitness devices spanning multiple styles, form factors, and price points to allow people to find the devices that fit their lifestyles and goals.  Advanced, purpose-built hardware and software technologies. Our connected health and fitness devices leverage industry-standard technologies, such as Bluetooth low energy, as well as proprietary technologies, such as our PurePulse continuous heart rate tracking, and our algorithms that more accurately measure and analyze user health and fitness metrics. Our online and mobile apps provide in-depth analysis and guidance and our highly-scalable cloud infrastructure enables millions of users around the world to engage with our platform in real-time.  Broad mobile compatibility and open API. Our broad mobile compatibility and open API enable a large and growing health and fitness ecosystem that provides additional value to our existing users and extends our reach to potential new users. Our users can sync their Fitbit devices with, and view their online dashboard on, their computers and over 150 mobile devices, including iOS, Android, and Windows Phone products, which has enabled us to build what we believe is the largest community of connected health and fitness device users.  Broad and differentiated go-to-market strategy. We sell our products in over 45,000 retail stores and in more than 50 countries, through our retailers websites, through our online store at Fitbit.com, and as part of our corporate wellness offering. We believe the breadth and depth of our established selling channels and prominent presence in retail stores are unmatched in the connected health and fitness category and would be difficult for a competitor to replicate.  Large and growing community and powerful network effects. The total number of registered users on our platform has grown from 1.1 million as of December 31, 2012, to 4.5 million as of December 31, 2013, to 14.6 million as of December 31, 2014, and to 19.0 million as of March 31, 2015. As our community of users continues to grow, we will develop a deeper understanding of our users and expect to deliver additional value to them through more detailed insights and analysis.  Direct relationship and continuous communication with our users. The connectivity of our devices allows us to better understand our users health and fitness goals and communicate the most relevant analysis, features, advice, and content to them throughout the day with our online dashboard, mobile apps, emails, and notifications. Our Growth Strategy We intend to maintain and extend our position as the leading platform for connected health and fitness. Key elements of our growth strategy include:  Continue to introduce innovative products. We will continue to develop the worlds most innovative and diverse connected health and fitness devices and we plan to continue to make significant investments in research and development to further strengthen our platform through both internally-developed and acquired technologies.  Introduce new features and services. We will continue to introduce innovative new features and services to increase user engagement and revenue. For example, we acquired FitStar in March 2015 to enhance our software and services offerings through interactive video-based exercise experiences on mobile devices and computers. * See Industry and Market Data.

5

 Expand brand awareness and drive sales of our products and services. We intend to increase our marketing efforts to further expand global awareness of our brand and drive greater sales of our products and services.  Increase global distribution through select new channels. We believe that international markets represent a significant growth opportunity for us and we intend to expand sales of our products and services globally through select retailers and strategic partnerships.  Further penetrate the corporate wellness market. We intend to increase our focus on building relationships with employers and wellness providers and increase revenue through employee wellness programs. Our Devices We believe everyones approach to fitness is different, so we have created products with a wide variety of styles, sizes, features, and price points.  Fitbit Zip is our entry-level wireless activity tracker that allows users to track the most important daily activity statistics such as steps, distance, calories burned, and active minutes. Fitbit Zip has a U.S. manufacturers suggested retail price, or U.S. MSRP, of $59.95.  Fitbit One is a more advanced clippable wireless tracker that tracks stairs climbed and sleep in addition to daily steps, distance, calories burned, and active minutes. Fitbit One has a U.S. MSRP of $99.95.  Fitbit Flex is our first wristband-style tracker, with a sleek and stylish design, that tracks steps, distance, calories burned, active minutes, and sleep. Fitbit Flex has a U.S. MSRP of $99.95.  Fitbit Charge is a wireless activity and sleep wristband that tracks steps, distance, calories burned, active minutes, floors climbed, and sleep. Fitbit Charge has a U.S. MSRP of $129.95.  Fitbit Charge HR is a wireless heart rate and activity wristband that has all the features available on the Fitbit Charge and also includes our proprietary PurePulse heart rate tracking technology. Fitbit Charge HR has a U.S. MSRP of $149.95.  Fitbit Surge is our fitness super watch that combines popular features of a GPS watch, heart rate tracker, activity tracker, and smartwatch. Fitbit Surge has a U.S. MSRP of $249.95.  Fitbit Aria is our Wi-Fi connected scale that tracks weight, body fat percentage, and BMI. Fitbit Aria has a U.S. MSRP of $129.95. We also sell various accessories, such as colored bands and clips for our devices, charging cables, and Fitbit apparel. These accessories are offered at U.S. MSRPs ranging from $4.95 to $195.00. Selected Risks Associated with Our Business Our business is subject to a number of risks and uncertainties, including those highlighted in the section titled Risk Factors immediately following this prospectus summary. Some of these risks are:  We operate in a highly competitive market;  We must be able to anticipate and satisfy consumer preferences in a timely manner;  We must successfully develop and timely introduce new products and services or enhance existing products and services;  We must be able to accurately forecast consumer demand for our products and services and adequately manage our inventory;

6

 Our quarterly operating results or other operating metrics may fluctuate significantly;  We rely on a limited number of third-party suppliers, contract manufacturers, and logistics providers over which we have limited control;  The market for connected health and fitness devices is still in the early stages of growth and may not continue to develop;  An economic downturn or economic uncertainty may adversely affect demand for our products and services;  Our current and future products and services may experience quality problems from time to time that can result in adverse publicity, product recalls, litigation, regulatory proceedings, and warranty claims;  We recalled one of our products, the Fitbit Force, in March 2014, due to reports of allergic reactions, which exposed us to U.S. Consumer Product Safety Commission, or CPSC, proceedings and private litigation;  Material disruption or breach of our information technology systems or those of third-parties could materially damage user and business partner relationships; and  The dual class structure of our common stock will have the effect of concentrating voting control with certain stockholders, including our directors, executive officers, and significant stockholders who will hold in the aggregate % of the voting power of our capital stock following the completion of this offering, which 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. Corporate Information We were incorporated in Delaware in March 2007 as Healthy Metrics Research, Inc. We changed our name to Fitbit, Inc. in October 2007. Our principal executive offices are located at 405 Howard Street, San Francisco, California 94105, and our telephone number is (415) 513-1000. Our website address is Fitbit.com. The information on, or that can be accessed through, our website is not incorporated by reference into this prospectus and should not be considered to be a part of this prospectus. Unless otherwise indicated, the terms Fitbit, the company, we, us, and our refer to Fitbit, Inc., a Delaware corporation, together with its consolidated subsidiaries. Fitbit, the Fitbit logo, Fitbit Zip, Fitbit One, Fitbit Flex, Fitbit Charge, Fitbit Charge HR, Fitbit Surge, Fitbit Aria, PurePulse, and our other registered or common law trade names, trademarks, or service marks appearing in this prospectus are our property. This prospectus contains additional trade names, trademarks, and service marks of other companies that are the property of their respective owners. Implications of Being an Emerging Growth Company As a company with less than $1.0 billion in revenue during our last completed fiscal year, we qualify as an emerging growth company as defined in the Jumpstart Our Business Startups Act of 2012, or the JOBS Act. An emerging growth company may take advantage of specified reduced reporting requirements that are otherwise applicable generally to public companies. These reduced reporting requirements include:  an exemption from compliance with the auditor attestation requirement on the effectiveness of our internal control over financial reporting;

7

 an exemption from compliance with any requirement that the Public Company Accounting Oversight Board may adopt regarding mandatory audit firm rotation or a supplement to the auditors report providing additional information about the audit and the financial statements;  reduced disclosure about our executive compensation arrangements;  an exemption from the requirements to obtain a non-binding advisory vote on executive compensation or a stockholder approval of any golden parachute arrangements; and  extended transition periods for complying with new or revised accounting standards. We will remain an emerging growth company until the earliest to occur of: (i) the end of the first fiscal year in which our annual gross revenue is $1.0 billion or more; (ii) the end of the first fiscal year in which we are deemed to be a large accelerated filer, as defined in the Securities Exchange Act of 1934, as amended, or the Exchange Act; (iii) the date on which we have, during the previous three-year period, issued more than $1.0 billion in non-convertible debt securities; and (iv) the end of the fiscal year during which the fifth anniversary of this offering occurs. We may choose to take advantage of some, but not all, of the available benefits under the JOBS Act. We are choosing to irrevocably opt out of the extended transition periods available under the JOBS Act for complying with new or revised accounting standards, but we currently intend to take advantage of the other exemptions discussed above. Accordingly, the information contained herein may be different than the information you receive from other public companies in which you hold stock.

8

THE OFFERING Class A common stock offered by us shares Class A common stock offered by the selling stockholders shares Over-allotment option offered by us and by the selling stockholders shares (with shares of Class A common stock being offered by us and shares of Class A common stock being offered by the selling stockholders) Class A common stock to be outstanding after this offering shares ( shares if the over-allotment option is exercised in full) Class B common stock to be outstanding after this offering shares ( shares if the over-allotment option is exercised in full) Total Class A and Class B common stock to be outstanding after this offering shares ( shares if the over-allotment option is exercised in full) Use of proceeds We estimate that the net proceeds from the sale of shares of our Class A common stock that we are selling in this offering will be approximately $ million, based upon an assumed initial public offering price of $ per share, which is the midpoint of the price range set forth on the cover page of this prospectus, after deducting estimated underwriting discounts and commissions and estimated offering expenses payable by us. We will not receive any proceeds from the sale of shares of our Class A common stock by the selling stockholders. The principal purposes of this offering are to increase our capitalization and financial flexibility, create a public market for our Class A common stock, and enable access to the public equity markets for us and our stockholders. We intend to use the net proceeds that we receive from this offering for working capital and other general corporate purposes, including research and development and sales and marketing activities, general and administrative matters, and capital expenditures. We may also use a portion of the net proceeds to invest in or acquire complementary businesses, products, services, technologies, or other assets. See the section titled Use of Proceeds for additional information.

9

Voting rights Shares of Class A common stock are entitled to one vote per share. Shares of Class B common stock are entitled to ten votes per share. Holders of our Class A common stock and Class B common stock will generally vote together as a single class, unless otherwise required by law or our restated certificate of incorporation. Each share of our Class B common stock will be convertible into one share of our Class A common stock at any time and will convert automatically upon certain transfers and upon the earlier of twelve years from the date of this prospectus or the date the holders of a majority of our Class B common stock elect to convert the Class B common stock to Class A common stock. The holders of our outstanding Class B common stock will hold % of the voting power of our outstanding capital stock following this offering, with our directors and executive officers and their affiliates holding % in the aggregate. These holders will have the ability to control the outcome of matters submitted to our stockholders for approval, including the election of our directors and the approval of any change in control transaction. See the sections titled Principal and Selling Stockholders and Description of Capital Stock for additional information. Proposed New York Stock Exchange symbol FIT The number of shares of our Class A and Class B common stock to be outstanding after this offering is based upon no shares of our Class A common stock and 121,508,763 shares of our Class B common stock outstanding as of March 31, 2015 (prior to the automatic conversion of shares of our Class B common stock into an equivalent number of shares of our Class A common stock upon their sale by the selling stockholders in this offering) and does not include:  31,619,974 shares of our Class B common stock issuable upon the exercise of options to purchase shares of our Class B common stock outstanding as of March 31, 2015, with a weighted-average exercise price of $3.29 per share;  1,471,063 shares of our Class B common stock issuable upon the exercise of options to purchase shares of our Class B common stock granted after March 31, 2015, with a weighted-average exercise price of $18.85 per share;  194,423 shares of our Class B common stock issuable upon the vesting of restricted stock units, or RSUs, outstanding as of March 31, 2015;  1,303,328 shares of our Class B common stock issuable upon the exercise of warrants to purchase convertible preferred stock outstanding as of March 31, 2015, with a weighted-average exercise price of $0.89 per share; and

10

 8,397,398 shares of our common stock reserved for future issuance under our equity compensation plans, consisting of: ¡ 5,897,398 shares of Class B common stock reserved for future issuance under our Amended and Restated 2007 Stock Plan, as amended, or 2007 Plan, as of March 31, 2015 (which reserve does not reflect the options to purchase shares of Class B common stock granted after March 31, 2015); and ¡ 2,500,000 shares of Class A common stock reserved for future issuance under our 2015 Employee Stock Purchase Plan, or 2015 ESPP, which will become effective on the date of this prospectus. Any remaining shares available for issuance under our 2007 Plan will become reserved for future issuance as Class A common stock under our 2015 Equity Incentive Plan, or 2015 Plan, which will become effective on the date immediately prior to the date of this prospectus, and we will cease granting awards under the 2007 Plan. Our 2015 Plan and 2015 ESPP also provide for automatic annual increases in the number of shares reserved thereunder. See the section titled Executive CompensationEmployee Benefit Plans for additional information. Except as otherwise indicated, all information in this prospectus assumes:  the amendment to our amended and restated certificate of incorporation in 2015 to redesignate our outstanding common stock as Class B common stock and create a new class of Class A common stock to be offered and sold in this offering and to effect a -for- split of our capital stock;  the conversion of all shares of our convertible preferred stock outstanding as of March 31, 2015 into an aggregate of 93,234,322 shares of our Class B common stock immediately prior to the completion of this offering;  the conversion of all outstanding warrants to purchase shares of convertible preferred stock into warrants to purchase the same number of shares of Class B common stock immediately prior to the completion of this offering;  the automatic conversion of shares of our Class B common stock into an equivalent number of shares of our Class A common stock upon their sale by the selling stockholders in this offering;  the filing and effectiveness of our restated certificate of incorporation and the effectiveness of our restated bylaws, each of which will occur immediately prior to the completion of this offering; and  no exercise by the underwriters of their option to purchase up to an additional shares of our Class A common stock from us and shares of our Class A common stock from the selling stockholders in this offering to cover over-allotments.

11

SUMMARY CONSOLIDATED FINANCIAL AND OTHER DATA The following tables summarize our consolidated financial and other data. We derived the summary consolidated statements of operations data for 2012, 2013, and 2014 from our audited consolidated financial statements included elsewhere in this prospectus. We derived the summary consolidated statements of operations data for the three months ended March 31, 2014 and 2015 and the summary consolidated balance sheet data as of March 31, 2015 from our unaudited consolidated financial statements included elsewhere in this prospectus. We have prepared the unaudited consolidated financial statements on the same basis as the audited consolidated financial statements and have included, in our opinion, all adjustments consisting only of normal recurring adjustments that we consider necessary for a fair statement of the financial information set forth in those statements. Our historical results are not necessarily indicative of the results that may be expected in the future. You should read this data together with our consolidated financial statements and related notes appearing elsewhere in this prospectus. As of or For the Year Ended

December 31, As of or For the Three

Months Ended

March 31, 2012 2013(1) 2014(1) 2014(1) 2015(1) (in thousands, except per share data) Consolidated Statements of Operations Data: Revenue $ 76,373 $ 271,087 $ 745,433 $ 108,815 $ 336,754 Cost of revenue (2) 49,733 210,836 387,776 64,046 167,545 Gross profit 26,640 60,251 357,657 44,769 169,209 Operating expenses: Research and development (2) 16,210 27,873 54,167 9,088 22,426 Sales and marketing (2) 10,237 26,847 112,005 11,273 43,867 General and administrative (2) 3,968 14,485 33,556 8,617 12,981 Total operating expenses 30,415 69,205 199,728 28,978 79,274 Operating income (loss) (3,775 ) (8,954 ) 157,929 15,791 89,935 Interest and other income (expense), net (150 ) (4,731 ) (18,156 ) (1,628 ) (13,544 ) Income (loss) before income taxes (3,925 ) (13,685 ) 139,773 14,163 76,391 Income tax expense 291 37,937 7,996 5,291

28,394



Net income (loss) $ (4,216 ) $ (51,622 ) $ 131,777 $ 8,872 $ 47,997 Net income (loss) per share attributable to common stockholders (3) : Basic $ (0.17 ) $ (1.98 ) $ 1.05 $ 0.06 $ 0.39 Diluted $ (0.17 ) $ (1.98 ) $ 0.94 $ 0.06 $ 0.33 Pro forma net income per share attributable to common stockholders (3) : Basic $ 1.21 $ 0.48 Diluted $ 1.07 $ 0.41 Other Data : Devices sold (4) 1,279 4,476 10,904 1,575 3,866 Paid active users (5) 558 2,570 6,700 3,867 9,517 Adjusted EBITDA (6) $ (2,401 ) $ 79,049 $ 191,042 $ 42,028 $ 93,383

12

(1) In March 2014, we recalled the Fitbit Force. See the section titled Managements Discussion and Analysis of Financial Condition and Results of OperationsFitbit Force Product Recall for additional information. The recall, which primarily affected our results for the fourth quarter of 2013 and the first quarter of 2014, had the following effect on our income (loss) before income taxes: Year Ended December 31, Three Months Ended

March 31, 2013 2014 2014 2015 (in thousands) Reduction of revenue $ (30,607 ) $ (8,112 ) $ (11,561 ) $  Incremental (benefit to) cost of revenue 51,205 11,339 10,602 (2,040 ) Impact on gross profit (81,812 ) (19,451 ) (12,163 ) 2,040 Incremental general and administrative expenses (benefit) 2,838 3,389 2,876 (142 ) Impact on income (loss) before income taxes $ (84,650 ) $ (22,840 ) $ (25,039 ) $ 2,182 (2) Includes stock-based compensation expense as follows: Year Ended December 31, Three Months Ended

March 31, 2012 2013 2014 2014 2015 (in thousands) Cost of revenue $ 15 $ 37 $ 890 $ 59 $ 446 Research and development 62 288 2,350 92 1,879 Sales and marketing 29 204 1,295 63 1,307 General and administrative 26 91 2,269 100 1,271 Total $ 132 $ 620 $ 6,804 $ 314 $ 4,903 (3) See notes 2, 3, and 15 of the notes to our consolidated financial statements included elsewhere in this prospectus for an explanation of the calculations of our net income (loss) per share attributable to common stockholders, basic and diluted, and pro forma net income per share attributable to common stockholders, basic and diluted. (4) See the section titled Managements Discussion and Analysis of Financial Condition and Results of OperationsKey Business MetricsDevices Sold for more information. (5) See the section titled Managements Discussion and Analysis of Financial Condition and Results of OperationsKey Business MetricsPaid Active Users for more information. (6) Adjusted EBITDA is a financial measure that is not calculated in accordance with generally accepted accounting principles in the United States, or U.S. GAAP. See the section titled Selected Consolidated Financial and Other DataAdjusted EBITDA for information regarding our use of adjusted EBITDA and a reconciliation of adjusted EBITDA to net income (loss). As of March 31, 2015 Actual Pro Forma(1) Pro Forma

As Adjusted(2)(3) (in thousands) Consolidated Balance Sheet Data: Cash and cash equivalents (4) $ 237,849 $ 237,849 $ Working capital (4) 174,813 174,813 Total assets (4) 669,349 669,349 Total long-term debt (4) 159,611 159,611 Redeemable convertible preferred stock warrant liability 26,132  Redeemable convertible preferred stock 67,814  Retained earnings 115,239 115,239 Total stockholders equity 141,906 235,852 (1) The pro forma column reflects (a) the redesignation of our outstanding common stock as Class B common stock in 2015, (b) the automatic conversion of all shares of our convertible preferred stock outstanding as of March 31, 2015 into shares of our Class B common stock, (c) the automatic conversion of the convertible preferred stock warrants to Class B common stock warrants, and the resulting remeasurement and assumed reclassification of the redeemable convertible preferred stock warrant liability to additional paid-in capital, and (d) the filing and effectiveness of our restated certificate of incorporation. (2) The pro forma as adjusted column reflects the items described in footnote (1) and the receipt of $ million in net proceeds from our sale of shares of Class A common stock in this offering at an assumed initial public offering price of $ per share, which is

13

the midpoint of the price range set forth on the cover page of this prospectus, after deducting estimated underwriting discounts and commissions and estimated offering expenses payable by us. A $1.00 increase or decrease in the assumed initial public offering price of $ per share, which is the midpoint of the price range set forth on the cover page of this prospectus, would increase or decrease our pro forma as adjusted cash and cash equivalents, working capital, total assets, and total stockholders equity by $ million, assuming that the number of shares offered by us, as set forth on the cover page of this prospectus, remains the same, and after deducting estimated underwriting discounts and commissions. (3) The pro forma as adjusted information discussed above is illustrative only and will be adjusted based on the actual public offering price and other terms of our initial public offering that will be determined at pricing. (4) Subsequent to March 31, 2015, we repaid $160.0 million of our long-term debt from our cash and cash equivalents. As a result, the long-term debt that would have been classified as long-term debt, less current portion, that was repaid was classified as long-term debt, current portion, on our consolidated balance sheet as of March 31, 2015.

14

RISK FACTORS

An investment 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, including the section titled Managements Discussion and Analysis of Financial Condition and Results of Operations and our consolidated financial statements and related notes, before making a decision to invest in our Class A common stock. Our business, operating results, financial condition, or prospects could be materially and adversely affected by any of these risks and uncertainties. If any of these risks actually occurs, the trading price of our Class A common stock could decline and you might lose all or part of your investment. Our business, operating results, financial performance, or prospects could also be harmed by risks and uncertainties not currently known to us or that we currently do not believe are material.

Risks Related to Our Business

We operate in a highly competitive market. If we do not compete effectively, our prospects, operating results, and financial condition could be adversely affected.

The connected health and fitness devices market is highly competitive, with companies offering a variety of competitive products and services. We expect competition in our market to intensify in the future as new and existing competitors introduce new or enhanced products and services that are potentially more competitive than our products and services. The connected health and fitness devices market has a multitude of participants, including specialized consumer electronics companies, such as Garmin, Jawbone, and Misfit, and traditional health and fitness companies, such as adidas and Under Armour. In addition, many large, broad-based consumer electronics companies either compete in our market or adjacent markets or have announced plans to do so, including Apple, Google, LG, Microsoft, and Samsung. For example, Apple has recently introduced the Apple Watch smartwatch, with broad-based functionalities, including some health and fitness tracking capabilities. We also compete with a wide range of stand-alone health and fitness-related mobile apps that can be purchased or downloaded through mobile app stores. We believe many of our competitors and potential competitors have significant competitive advantages, including longer operating histories, ability to leverage their sales efforts and marketing expenditures across a broader portfolio of products and services, larger and broader customer bases, more established relationships with a larger number of suppliers, contract manufacturers, and channel partners, greater brand recognition, ability to leverage app stores which they may operate, and greater financial, research and development, marketing, distribution, and other resources than we do. Our competitors and potential competitors may also be able to develop products or services that are equal or superior to ours, achieve greater market acceptance of their products and services, and increase sales by utilizing different distribution channels than we do. Some of our competitors may aggressively discount their products and services in order to gain market share, which could result in pricing pressures, reduced profit margins, lost market share, or a failure to grow market share for us. If we are not able to compete effectively against our current or potential competitors, our prospects, operating results, and financial condition could be adversely affected.

If we are unable to anticipate and satisfy consumer preferences in a timely manner, our business may be adversely affected.

Our success depends on our ability to anticipate and satisfy consumer preferences in a timely manner. All of our products are subject to changing consumer preferences that cannot be predicted with certainty. Consumers may decide not to purchase our products and services as their preferences could shift rapidly to different types of connected health and fitness devices or away from these types of products and services altogether, and our future success depends in part on our ability to anticipate and respond to shifts in consumer preferences. In addition, our newer products and services that have additional features, such as the Fitbit Charge, Fitbit Charge HR, and Fitbit Surge, may have higher prices than many of our earlier products and the products of some of our competitors, which may not appeal to consumers or only appeal to a smaller subset of consumers. It is also possible that competitors could introduce new products and services that negatively impact consumer preference for our

15

connected health and fitness devices, which could result in decreased sales of our products and services and a loss in market share. Accordingly, if we fail to anticipate and satisfy consumer preferences in a timely manner, our business may be adversely affected.

If we are unable to successfully develop and timely introduce new products and services or enhance existing products and services, our business may be adversely affected.

We must continually develop and introduce new products and services and improve and enhance our existing products and services to maintain or increase our sales. The success of new or enhanced products and services may depend on a number of factors including, anticipating and effectively addressing consumer preferences and demand, the success of our sales and marketing efforts, timely and successful research and development, effective forecasting and management of product demand, purchase commitments, and inventory levels, effective management of manufacturing and supply costs, and the quality of or defects in our products.

The development of our products and services is complex and costly, and we typically have several products and services in development at the same time. Given the complexity, we occasionally have experienced, and could experience in the future, delays in completing the development and introduction of new and enhanced products and services. Problems in the design or quality of our products or services may also have an adverse effect on our brand, business, financial condition, and operating results. Unanticipated problems in developing products and services could also divert substantial research and development resources, which may impair our ability to develop new products and services and enhancements of existing products and services, and could substantially increase our costs. If new or enhanced product and service introductions are delayed or not successful, we may not be able to achieve an acceptable return, if any, on our research and development efforts, and our business may be adversely affected.

Our operating results could be materially harmed if we are unable to accurately forecast consumer demand for our products and services and adequately manage our inventory.

To ensure adequate inventory supply, we must forecast inventory needs and expenses and place orders sufficiently in advance with our suppliers and contract manufacturers based on our estimates of future demand for particular products. Our ability to accurately forecast demand for our products and services could be affected by many factors, including an increase or decrease in customer demand for our products and services or for products and services of our competitors, product and service introductions by competitors, unanticipated changes in general market conditions, and the weakening of economic conditions or consumer confidence in future economic conditions. Due to the recent rapid growth in demand for our connected health and fitness devices, and particularly in connection with new product introductions, we face challenges acquiring adequate and timely supplies of our products to satisfy the levels of demand, which we believe negatively affects our revenue. This risk may be exacerbated by the fact that we may not carry a significant amount of inventory, either directly or with our contract manufacturers or logistics providers to satisfy short-term demand increases. If we fail to accurately forecast customer demand, we may experience excess inventory levels or a shortage of products available for sale.

Inventory levels in excess of customer demand may result in inventory write-downs or write-offs and the sale of excess inventory at discounted prices, which would cause our gross margin to suffer and could impair the strength of our brand. Conversely, if we underestimate customer demand for our products and services, our contract manufacturers may not be able to deliver products to meet our requirements, and this could result in damage to our brand and customer relationships and adversely affect our revenue and operating results.

16

Our quarterly operating results or other operating metrics may fluctuate significantly, which could cause the trading price of our Class A common stock to decline.

Our quarterly operating results and other operating metrics have fluctuated in the past and may continue to fluctuate from quarter to quarter. We expect that this trend will continue as a result of a number of factors, many of which are outside of our control and may be difficult to predict, including:

 the level of demand for our connected health and fitness devices and our ability to maintain or increase the size and engagement of our community of users;

 the timing and success of new product and service introductions by us or our competitors or any other change in the competitive landscape of our market;

 the mix of products sold in a quarter;

 the continued market acceptance of, and the growth of the market for, connected health and fitness devices;

 pricing pressure as a result of competition or otherwise;

 delays or disruptions in our supply, manufacturing, or distribution chain;

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

 seasonal buying patterns of consumers;

 increases in and timing of sales and marketing and other operating expenses that we may incur to grow and expand our operations and to remain competitive;

 insolvency, credit, or other difficulties faced by our distributors and retailers, affecting their ability to purchase or pay for our products;

 insolvency, credit, or other difficulties confronting our suppliers, contract manufacturers, or logistics providers leading to disruptions in our supply or distribution chain;

 levels of product returns, stock rotation, and price protection rights;

 adverse litigation judgments, settlements, or other litigation-related costs;

 changes in the legislative or regulatory environment, such as with respect to privacy, information security, health and wellness devices, consumer product safety, and advertising;

 product recalls, regulatory proceedings, or other adverse publicity about our products;

 fluctuations in foreign exchange rates;

 costs 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.

Any one of the factors above or the cumulative effect of some of the factors above may result in significant fluctuations in our operating results.

The variability and unpredictability of our quarterly operating results or other operating metrics could result in our failure to meet our expectations or those of any analysts that cover us or investors with respect to revenue or other operating results 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 substantially, and we could face costly lawsuits, including securities class action suits.

17

We rely on a limited number of suppliers, contract manufacturers, and logistics providers, and each of our products is manufactured by a single contract manufacturer.

We rely on a limited number of suppliers, contract manufacturers, and logistics providers. In particular, we use contract manufacturers located in Asia, and each of our products is manufactured by a single contract manufacturer. Flextronics is our primary contract manufacturer and is currently the sole manufacturer of the majority of our devices. Our reliance on sole contract manufacturers for each of our products increases our risks since we do not currently have any alternative or replacement manufacturers. In the event of an interruption from a contract manufacturer, we may not be able to develop alternate or secondary sources without incurring material additional costs and substantial delays. Furthermore, these risks could materially and adversely affect our business if one of our contract manufacturers is impacted by a natural disaster or other interruption at a particular location because each of our contract manufacturers produces our products from a single location. In addition, some of our suppliers, contract manufacturers, and logistics providers may have more established relationships with our competitors and potential competitors, and as a result of such relationships, such suppliers, contract manufacturers, and logistics providers may choose to limit or terminate their relationship with us.

If we experience significantly increased demand, or if we need to replace an existing supplier, contract manufacturer, or logistics provider, we may be unable to supplement or replace such supply, contract manufacturing, or logistics capacity on terms that are acceptable to us, which may undermine our ability to deliver our products to customers in a timely manner. For example, for certain of our products, it may take a significant amount of time to identify a contract manufacturer that has the capability and resources to build the product to our specifications in sufficient volume. Identifying suitable suppliers, contract manufacturers, and logistics providers is an extensive process that requires us to become satisfied with their quality control, technical capabilities, responsiveness and service, financial stability, regulatory compliance, and labor and other ethical practices. Accordingly, a loss of any key supplier, contract manufacturer, or logistics provider could adversely impact our revenue and operating results.

We have limited control over our suppliers, contract manufacturers, and logistics providers, which subjects us to significant risks, including the potential inability to obtain or produce quality products on a timely basis or in sufficient quantity.

We have limited control over our suppliers, contract manufacturers, and logistics providers, including aspects of their specific manufacturing processes and their labor, environmental, or other practices, which subjects us to significant risks, including the following:

 inability to satisfy demand for our products;

 reduced control over delivery timing and product reliability;

 reduced ability to oversee the manufacturing process and components used in our products;

 reduced ability to monitor compliance with our product manufacturing specifications;

 reduced ability to develop comprehensive manufacturing specifications that take into account materials shortages, materials substitutions, and variance in the manufacturing capabilities of our third-party contract manufacturers;

 price increases;

 the failure of a key supplier, contract manufacturer, or logistics provider to perform its obligations to us for technical, market, or other reasons;

 difficulties in establishing additional contract manufacturing relationships if we experience difficulties with our existing contract manufacturers;

 shortages of materials or components;

 misappropriation of our intellectual property;

18

 exposure to natural catastrophes, political unrest, terrorism, labor disputes, and economic instability resulting in the disruption of trade from foreign countries in which our products are manufactured;

 changes in local economic conditions in countries where our suppliers, contract manufacturers, or logistics providers are located;

 the imposition of new laws and regulations, including those relating to labor conditions, quality and safety standards, imports, duties, taxes, and other charges on imports, as well as trade restrictions and restrictions on currency exchange or the transfer of funds; and

 insufficient warranties and indemnities on components supplied to our contract manufacturers.

If there are defects in the manufacture of our products by our contract manufacturers, we may face negative publicity, government investigations, and litigation and we may not be fully compensated by our contract manufacturers for any financial or other liability that we suffer as a result.

Because many of the key components in our products come from limited or sole sources of supply, we are susceptible to supply shortages, long lead times for components, and supply changes, any of which could disrupt our supply chain.

Many of the key components used to manufacture our products come from limited or sole sources of supply. Our contract manufacturers generally purchase these components on our behalf, subject to certain approved supplier lists, and we do not have any long-term arrangements with our suppliers. We are therefore subject to the risk of shortages and long lead times in the supply of these components and the risk that our suppliers discontinue or modify components used in our products. In addition, the lead times associated with certain components are lengthy and preclude rapid changes in quantities and delivery schedules. We have in the past experienced and may in the future experience component shortages, and the predictability of the availability of these components may be limited. While component shortages have historically been immaterial, they could be material in the future. In the event of a component shortage or supply interruption from suppliers of these components, we may not be able to develop alternate sources in a timely manner. Developing alternate sources of supply for these components may be time-consuming, difficult, and costly and we may not be able to source these components on terms that are acceptable to us, or at all, which may undermine our ability to meet our requirements or to fill our orders in a timely manner. Any interruption or delay in the supply of any of these parts or components, or the inability to obtain these parts or components from alternate sources at acceptable prices and within a reasonable amount of time, would harm our ability to meet our scheduled product deliveries to our customers and users. This could harm our relationships with our channel partners and users and could cause delays in shipment of our products and adversely affect our operating results. In addition, increased component costs could result in lower gross margins. If we are unable to buy these components in quantities sufficient to meet our requirements on a timely basis, we will not be able to deliver products and services to our customers and users.

The market for connected health and fitness devices is still in the early stages of growth and if it does not continue to grow, grows more slowly than we expect, or fails to grow as large as we expect, our business and operating results would be harmed.

The market for connected health and fitness devices is relatively new and unproven, and it is uncertain whether connected health and fitness devices will sustain high levels of demand and wide market acceptance. Our success will depend to a substantial extent on the willingness of people to widely adopt these products and services. In part, adoption of our products and services will depend on the increasing prevalence of connected health and fitness devices as well as new entrants to the connected health and fitness device market to raise the profile of both the market as a whole and our own platform. Our connected health and fitness devices have largely been used to measure and track activities such as walking, running, and sleeping. However, they have not been as widely adopted for other sports, exercise, and activities such as cycling, skiing, and swimming for which

19

other niche products are more often used. Furthermore, some individuals may be reluctant or unwilling to use connected health and fitness devices because they have concerns regarding the risks associated with data privacy and security. If the wider public does not perceive the benefits of our connected health and fitness devices or chooses not to adopt them as a result of concerns regarding privacy or data security or for other reasons, then the market for these products and services may not further develop, it may develop more slowly than we expect, or it may not achieve the growth potential we expect it to, any of which would adversely affect our operating results. The development and growth of this relatively new market may also prove to be a short-term trend.

An economic downturn or economic uncertainty may adversely affect consumer discretionary spending and demand for our products and services.

Our products and services may be considered discretionary items for consumers. Factors affecting the level of consumer spending for such discretionary items include general economic conditions, and other factors, such as consumer confidence in future economic conditions, fears of recession, the availability and cost of consumer credit, levels of unemployment, and tax rates. As global economic conditions continue to be volatile or economic uncertainty remains, trends in consumer discretionary spending also remain unpredictable and subject to reductions. Unfavorable economic conditions may lead consumers to delay or reduce purchases of our products and services and consumer demand for our products and services may not grow as we expect. Our sensitivity to economic cycles and any related fluctuation in consumer demand for our products and services may have an adverse effect on our operating results and financial condition.

Our current and future products and services may experience quality problems from time to time that can result in adverse publicity, product recalls, litigation, regulatory proceedings, and warranty claims resulting in significant direct or indirect costs, decreased revenue and operating margin, and harm to our brand.

We sell complex products and services that could contain design and manufacturing defects in their materials, hardware, and firmware. These defects could include defective materials or components, or bugs that can unexpectedly interfere with the products intended operations or cause injuries to users. Although we extensively and rigorously test new and enhanced products and services before their release, there can be no assurance we will be able to detect, prevent, or fix all defects.

Failure to detect, prevent, or fix defects could result in a variety of consequences including greater number of returns of products than expected from users and retailers, regulatory proceedings, product recalls, and litigation, which could harm our revenue and operating results. We generally provide a 45-day right of return for purchases through Fitbit.com and a 12-month warranty on all of our products, except in the European Union, where we provide a two-year warranty on all of our products. The occurrence of real or perceived quality problems or material defects in our current and future products could expose us to warranty claims in excess of our current reserves. As of December 31, 2014, our reserves for warranty claims were $20.1 million, or 3% of our revenue for 2014. Moreover, we offer limited stock rotation rights and price protection to our distributors. If we experience greater returns from retailers or users in excess of our reserves, our business and operating results could be harmed. In addition, any negative publicity related to the perceived quality and safety of our products could also affect our brand and decrease demand for our products and services, and adversely affect our operating results and financial condition.

Furthermore, our products are used to track and display various information about users activities, such as daily steps taken, calories burned, distance traveled, floors climbed, active minutes, sleep duration and quality, and heart rate and GPS-based information such as speed, distance, and exercise routes. If our products fail to provide accurate measurements and data to our users, or if there are reports of inaccurate measurements, we may become the subject of negative publicity and our brand, operating results, and business could be harmed.

20

We recalled the Fitbit Force in March 2014. The recall has exposed us to CPSC regulatory proceedings and extensive litigation in various jurisdictions, including multi-jurisdiction complex federal and state class action and personal injury claims, which required significant management attention and disrupted our business operations, and adversely affected our financial condition, operating results, and our brand.

In March 2014, we recalled one of our products, the Fitbit Force, after some of our users experienced allergic reactions to adhesives in the wristband. These reactions included skin irritation, rashes, and blistering. The recall had a negative impact on our operating results, primarily in our fourth quarter of 2013 and the first quarter of 2014. See the section titled Managements Discussion and Analysis of Financial Condition and Results of OperationsFitbit Force Product Recall for additional information regarding the financial impact of the recall on our historical operating results. We have provided and are continuing to provide full refunds to consumers who return the Fitbit Force. Users may also exchange their Fitbit Force for a Fitbit Charge. If returns of the Fitbit Force or other costs related to the recall are higher than anticipated, we will be required to increase our reserves related to the recall which would negatively impact our operating results in the future.

The recall is being conducted in conjunction with the CPSC, which has been monitoring recall effectiveness and compliance. In addition to the financial impacts discussed elsewhere in this prospectus, this recall requires us to provide a significant amount of information to the CPSC and to continue to provide reports on an ongoing basis, which takes significant time and internal and external resources. Because the Fitbit Force was primarily sold in the United States, we have not had inquiries from any similar foreign regulatory agencies.

A large number of lawsuits, including multi-jurisdiction complex federal and state class action and personal injury claims, were filed against us relating to the Fitbit Force. We have also had several consumers bring lawsuits relating to our Fitbit Flex product. These litigation matters have required significant attention of our management and resources and disrupted the ordinary course of our business operations. While we have settled all of the class action lawsuits, a number of personal injury claims remain outstanding. While we do not believe that these on-going legal proceedings relating to the Fitbit Force or Fitbit Flex are material, due to the inherent uncertainties of litigation, we cannot accurately predict the ultimate outcome of any such proceedings and these actions or other third-party claims against us will result in the diversion of management time and attention from other aspects of our business and may cause us to incur substantial litigation or settlement costs.

In addition, the CPSC conducted an investigation into the Fitbit Flex and, although it did not find a substantial product hazard in the Fitbit Flex, there can be no assurances that product hazards or other defects will not be found in the future with respect to the Fitbit Flex or our other products. The Fitbit Force product recall, regulatory proceedings, and litigation have had and may continue to have, and any future recalls, regulatory proceedings, and litigation could have an adverse impact on our financial condition, operating results, and brand. Furthermore, because of the global nature of our product sales, in the event we experience defects with respect to products sold outside the United States, we could become subject to recalls, regulatory proceedings, and litigation by foreign governmental agencies and private litigants, which could significantly increase the costs of managing any product issues. Any ongoing and future regulatory proceedings or litigation, regardless of their merits, could further divert managements attention from our operations and result in substantial legal fees and other costs.

There have been recent reports of small numbers of users of some of our newer products experiencing skin irritations, which could result in additional negative publicity or otherwise harm our business.

Due to the nature of some of our wearable devices, some users have had in the past and may in the future experience skin irritations or other biocompatibility issues not uncommon with jewelry or other wearable products that stay in contact with skin for extended periods of time. Recently, there have been news reports of some users of Fitbit Charge, Fitbit Charge HR, and Fitbit Surge experiencing skin irritations. This negative publicity could harm sales of our products and also adversely affect our relationships with retailers that sell our products, including causing them to be reluctant to continue to sell our products. In addition, if large numbers of users experience these problems, we could be subject to inquiries from the CPSC or other U.S. or foreign

21

regulatory agencies and face personal injury or class action litigation, any of which could have a material adverse impact on our business, financial condition, and operating results.

Any material disruption or breach of our information technology systems, such as the five-hour outage we experienced during the peak holiday season in December 2014, or those of third-party partners could materially damage user and business partner relationships, and subject us to significant reputational, financial, legal, and operational consequences.

We depend on our information technology systems, as well as those of third parties, to develop new products and services, operate our website, host and manage our services, store data, process transactions, respond to user inquiries, and manage inventory and our supply chain. Any material disruption or slowdown of our systems or those of third parties whom we depend upon, including a disruption or slowdown caused by our failure to successfully manage significant increases in user volume or successfully upgrade our or their systems, system failures, viruses, security breaches, or other causes, could cause information, including data related to orders, to be lost or delayed which couldespecially if the disruption or slowdown occurred during the holiday seasonresult in delays in the delivery of products to stores and users or lost sales, which could reduce demand for our merchandise, harm our brand and reputation, and cause our revenue to decline. For example, during the peak holiday season in December 2014, we suffered an approximately five-hour outage of our information systems due to high levels of platform usage, which rendered us unable to process and support new users signing onto our platform during that time. If changes in technology cause our information systems, or those of third parties whom we depend upon, to become obsolete, or if our or their information systems are inadequate to handle our growth, we could lose users and our business and operating results could be adversely affected.

We collect, store, process, and use personal information and other customer data, which subjects us to governmental regulation and other legal obligations related to privacy, information security, and data protection, and our actual or perceived failure to comply with such obligations could harm our business.

We collect, store, process, and use personal information and other user data, and we rely on third parties that are not directly under our control to do so as well. Our users health and fitness-related data and other highly personal information may include, among other information, names, addresses, phone numbers, email addresses, payment account information, height, weight, and biometric information such as heart rates, sleeping patterns, GPS-based location, and activity patterns. Due to the volume and sensitivity of the personal information and data we manage and the nature of our products, the security features of our platform and information systems are critical. If our security measures, some of which are managed by third parties, are breached or fail, unauthorized persons may be able to obtain access to sensitive user data. If we or our third-party service providers, business partners, or third-party apps with which our users choose to share their Fitbit data were to experience a breach of systems compromising our users sensitive data, our brand and reputation could be adversely affected, use of our products and services could decrease, and we could be exposed to a risk of loss, litigation, and regulatory proceedings. Depending on the nature of the information compromised, in the event of a data breach or other unauthorized access to our user data, we may also have obligations to notify users about the incident and we may need to provide some form of remedy, such as a subscription to a credit monitoring service, for the individuals affected by the incident. A growing number of legislative and regulatory bodies have adopted consumer notification requirements in the event of unauthorized access to or acquisition of certain types of personal data. Such breach notification laws continue to evolve and may be inconsistent from one jurisdiction to another. Complying with these obligations could cause us to incur substantial costs and could increase negative publicity surrounding any incident that compromises user data. Our users may also accidentally disclose or lose control of their passwords, creating the perception that our systems are not secure against third-party access. Additionally, if third parties we work with, such as vendors or developers, violate applicable laws, agreements, or our policies, such violations may also put our users information at risk and could in turn have an adverse effect on our business. While we maintain insurance coverage that, subject to policy terms and conditions and a significant self-insured retention, is designed to address certain aspects of cyber risks, such insurance coverage may be insufficient to cover all losses or all types of claims that may arise in the continually evolving area of cyber risk.

22

Our success depends on our ability to maintain our brand. If events occur that damage our brand, our business and financial results may be harmed.

Our success depends on our ability to maintain the value of the Fitbit brand. The Fitbit name is integral to our business as well as to the implementation of our strategies for expanding our business. Maintaining, promoting, and positioning our brand will depend largely on the success of our marketing and merchandising efforts, our ability to provide consistent, high quality products and services, and our ability to successfully secure, maintain, and defend our rights to use the Fitbit and other trademarks important to our brand. Our brand could be harmed if we fail to achieve these objectives or if our public image or brand were to be tarnished by negative publicity. For example, there has been recent media coverage of some of the users of our products reporting skin irritation. We also believe that our reputation and brand may be harmed if we fail to maintain a consistently high level of customer service. Maintaining, protecting, and enhancing our brand may require us to make substantial investments, and these investments may not be successful. If we fail to successfully maintain, promote, and position our brand and protect our reputation or if we incur significant expenses in this effort, our business, financial condition and operating results may be adversely affected.

The failure to effectively manage the introduction of new or enhanced products may adversely affect our operating results.

We must successfully manage introductions of new or enhanced products. Introductions of new or enhanced products could adversely impact the sales of our existing products to retailers and consumers. For instance, retailers often purchase less of our existing products in advance of new product launches. Moreover, consumers may decide to purchase new or enhanced products instead of existing products. This could lead to excess inventory and discounting of our existing products. In addition, we have historically incurred higher levels of sales and marketing expenses accompanying each product introduction. Accordingly, if we fail to effectively manage introductions of new or enhanced products, our operating results would be harmed.

We depend on retailers and distributors to sell and market our products, and our failure to maintain and further develop our sales channels could harm our business.

We primarily sell our products through retailers and distributors and depend on these third-parties to sell and market our products to consumers. Any changes to our current mix of retailers and distributors could adversely affect our gross margin and could negatively affect both our brand image and our reputation. Our sales depend, in part, on retailers adequately displaying our products, including providing attractive space and point of purchase, or POP, displays in their stores, and training their sales personnel to sell our products. If our retailers and distributors are not successful in selling our products, our revenue would decrease and we could experience lower gross margin due to product returns or price protection claims. Our retailers also often offer products and services of our competitors in their stores. In addition, our success in expanding and entering into new markets internationally will depend on our ability to establish relationships with new retailers and distributors. We also sell and will need to continue to expand our sales through online retailers, such as Amazon.com. If we do not maintain our relationship with existing retailers and distributors or develop relationships with new retailers and distributors our ability to sell our products and services could be adversely affected and our business may be harmed.

In 2014 and for the three months ended March 31, 2015, our five largest retailers and distributors accounted for approximately 49% and 54% of our revenue, respectively. Of these retailers and distributors, Wynit Distribution, Best Buy, and Amazon.com accounted for approximately 13%, 12%, and 11% of our revenue for 2014, respectively, and approximately 19%, 10%, and 11% of our revenue for the three months ended March 31, 2015, respectively. Accordingly, the loss of a small number of our large retailers and distributors, or the reduction in business with one or more of these retailers and distributors, could have a significant adverse impact on our operating results. While we have agreements with these large retailers and distributors, these agreements do not require them to purchase any meaningful amount of our products.

23

Consolidation of retailers or concentration of retail market share among a few retailers may increase and concentrate our credit risk and impair our ability to sell products.

The wearable, fitness, and electronics retail markets in some countries are dominated by a few large retailers with many stores. These retailers have in the past increased their market share and may continue to do so in the future by expanding through acquisitions and construction of additional stores. These situations concentrate our credit risk with a relatively small number of retailers, and, if any of these retailers were to experience a shortage of liquidity, it would increase the risk that their outstanding payables to us may not be paid. In addition, increasing market share concentration among one or a few retailers in a particular country or region increases the risk that if any one of them substantially reduces their purchases of our connected health and fitness devices, we may be unable to find a sufficient number of other retail outlets for our products to sustain the same level of sales. Any reduction in sales by our retailers would adversely affect our revenue, operating results, and financial condition.

The insolvency, credit problems, or other financial difficulties confronting our retailers and distributors could expose us to financial risk.

Some of our retailers and distributors have experienced financial difficulties in the past. The insolvency, credit problems, or other financial difficulties confronting our retailers and distributors could expose us to financial risk. Financial difficulties of our retailers and distributors could impede their effectiveness and also expose us to risks if they are unable to pay for the products they purchase from us. The difficulties of retailers and distributors may also lead to price cuts of our products and adverse effects on our brand and operating results. Any reduction in sales by our current retailers or distributors, loss of large resellers or distributors, or decrease in revenue from our retailers or distributors could adversely affect our revenue, operating results, and financial condition.

We have recently begun to spend significant amounts on advertising and other marketing campaigns to acquire new users, which may not be successful or cost-effective.

We have recently begun to spend significant amounts on advertising and other marketing campaigns, such as television, cinema, print advertising, and social media, as well as increased promotional activities, to acquire new users and we expect our marketing expenses to increase in the future as we continue to spend significant amounts to acquire new users and increase awareness of our products and services. In 2014 and for the three months ended March 31, 2015, advertising expenses were $71.9 million and $21.1 million, respectively, representing approximately 10% and 6% of our revenue, respectively. While we seek to structure our advertising campaigns in the manner that we believe is most likely to encourage people to use our products and services, we may fail to identify advertising opportunities that satisfy our anticipated return on advertising spend as we scale our investments in marketing, accurately predict user acquisition, or fully understand or estimate the conditions and behaviors that drive user behavior. If for any reason any of our advertising campaigns prove less successful than anticipated in attracting new users, we may not be able to recover our advertising spend, and our rate of user acquisition may fail to meet market expectations, either of which could have an adverse effect on our business. There can be no assurance that our advertising and other marketing efforts will result in increased sales of our products and services.

If we continue to grow at a rapid pace, we may not be able to effectively manage our growth and the increased complexity of our business, which could negatively impact our brand and financial performance.

We were founded in 2007 and have expanded our operations rapidly since our inception. Our employee headcount and the scope and complexity of our business have increased significantly, with the number of employees increasing from 222 as of December 31, 2013 to 579 as of March 31, 2015, and we expect headcount growth to continue for the foreseeable future. If our operations continue to grow at a rapid pace, we may experience difficulties in obtaining components for our products in quantities sufficient to meet market demand, as well as delays in production and shipments, as our products are subject to risks associated with third-party sourcing and manufacturing. We could be required to continue to expand our sales and marketing, product development, and distribution functions, to upgrade our management information systems and other processes and technology, and to obtain more space for our expanding workforce. This expansion could increase the strain on our resources, and we

24

could experience serious operating difficulties, including difficulties in hiring, training, and managing an increasing number of employees. If we do not adapt to meet these evolving challenges, and if the current and future members of our management team do not effectively scale with our growth, we may experience erosion to our brand, the quality of our products and services may suffer, and our corporate culture may be harmed.

Because we have only a limited history operating our business at its current scale, it is difficult to evaluate our current business and future prospects, including our ability to plan for and model future growth. Our limited operating experience at this scale, combined with the rapidly evolving nature of the market in which we sell our products and services, substantial uncertainty concerning how these markets may develop, and other economic factors beyond our control, reduces our ability to accurately forecast quarterly or annual revenue. As such, any predictions about our future revenue and expenses may not be as accurate as they would be if we had a longer operating history or operated in a more developed and predictable market. Failure to manage our future growth effectively could have an adverse effect on our business, which, in turn, could have an adverse impact on our operating results and financial condition.

We may not be able to sustain our revenue growth rate or profitability in the future.

Our recent revenue growth should not be considered indicative of our future performance. As we grow our business, we expect our revenue growth rates to slow in future periods due to a number of reasons, which may include slowing demand for our products and services, increasing competition, a decrease in the growth of our overall market, our failure, for any reason, to continue to capitalize on growth opportunities, or the maturation of our business.

While we achieved profitability in 2014, we have not consistently achieved profitability on a quarterly or annual basis. We expect expenses to increase substantially in the near term, particularly as we make significant investments in our research and development and sales and marketing organizations, expand our operations and infrastructure both domestically and internationally, develop new products and services, and enhance our existing products and services. In addition, in connection with operating as 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 these increases in our operating expenses, we may not be profitable in future periods.

To date, we have derived substantially all of our revenue from sales of our connected health and fitness devices, and sales of our subscription-based premium services have historically accounted for less than 1% of our revenue.

To date, substantially all of our revenue has been derived from sales of our connected health and fitness devices, and we expect to continue to derive the substantial majority of our revenue from sales of these devices for the foreseeable future. In each of 2012, 2013, 2014, and the three months ended March 31, 2014 and 2015, we derived less than 1% of our revenue from sales of our subscription-based premium services. However, in the future we expect to increase sales of subscriptions to these services. Our inability to successfully sell and market our premium services could deprive us of a potentially significant source of revenue in the future. In addition, sales of our premium services may lead to additional sales of our connected health and fitness devices and user engagement with our platform. As a result, our future growth and financial performance may depend, in part, on our ability to sell more subscriptions to our premium services.

Our business is subject to a variety of U.S. and foreign laws and regulations that are continuously evolving, including those related to privacy, data security, and data protection due to our collection, processing, and use of personal information and other user data, such as the U.S.-E.U. Safe Harbor Framework, which covers the transfer of personal data from the European Union to the United States.

We are or may become subject to a variety of laws and regulations in the United States and abroad that involve matters central to our business, including laws and regulations regarding privacy, data protection, data

25

security, data retention, consumer protection, advertising, electronic commerce, intellectual property, manufacturing, anti-bribery and anti-corruption, and economic or other trade prohibitions or sanctions. These laws and regulations are continuously evolving and developing. The scope and interpretation of the laws that are or may be applicable to us are often uncertain and may be conflicting, particularly with respect to foreign laws.

In particular, there are numerous U.S. federal, state, and local laws and regulations and foreign laws and regulations regarding privacy and the collection, sharing, use, processing, disclosure, and protection of personal information and other user data, the scope of which is changing, subject to differing interpretations, and may be inconsistent among different jurisdictions. We strive to comply with all applicable laws, policies, legal obligations, and industry codes of conduct relating to privacy, data security, and data protection. However, given that the scope, interpretation, and application of these laws and regulations are often uncertain and may be conflicting, it is possible that these obligations may be interpreted and applied in a manner that is inconsistent from one jurisdiction to another and may conflict with other rules or our practices. Any failure or perceived failure to comply with our privacy or security policies or privacy-related legal obligations by us or third-party service-providers or the failure or perceived failure by third-party apps, with which our users choose to share their Fitbit data, to comply with their privacy policies or privacy-related legal obligations as they relate to the Fitbit data shared with them, or any compromise of security that results in the unauthorized release or transfer of personally identifiable information or ot