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

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

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Facebook. Facebook is a mobile application and website that enables people to connect, share, discover, and communicate with each other on mobile devices and personal computers. We had 1.04 billion daily active users (DAUs) on average in December 2015, an increase of 17% compared to December 2014. We had 934 million DAUs who accessed Facebook from a mobile device on average in December 2015, an increase of 25% compared to December 2014. There are a number of different ways to engage with people on Facebook, the most important of which is News Feed which displays an algorithmically-ranked series of stories and advertisements individualized for each person.

•	Instagram. Instagram is a mobile application that enables people to take photos or videos, customize them with filter effects, and share them with friends and followers in a photo feed or send them directly to friends.

•	Messenger. Messenger is a messaging application available for mobile and web on a variety of platforms and devices. Messenger enables people to reach others instantly and simply, and also enables businesses to engage with customers seamlessly and securely.

•	WhatsApp. WhatsApp Messenger is a fast, simple and reliable mobile messaging application that is used by people around the world and is available on a variety of mobile platforms.

•	Oculus. Our Oculus virtual reality technology and content platform power products that allow people to enter a completely immersive and interactive environment to play games, consume content, and connect with others.

•	Companies that offer products that replicate the full range of capabilities we provide. For example, Google has integrated social functionality into a number of its products, including search and Android, as well as other, largely regional, social networks that have strong positions in particular countries.

•	Companies that develop applications, particularly mobile applications, that provide social or other communications functionality, such as messaging, photo- and video-sharing, and micro-blogging.

•	Companies that provide web- and mobile-based information and entertainment products and services that are designed to engage people and capture time spent on mobile devices and online.

•	Traditional, online, and mobile businesses that provide media for marketers to reach their audiences and/or develop tools and systems for managing and optimizing advertising campaigns.

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Item 1A.	Risk Factors

•	users increasingly engage with other products or services;

•	we fail to introduce new products or services that users find engaging or if we introduce new products or services that are not favorably received;

•	users feel that their experience is diminished as a result of the decisions we make with respect to the frequency, prominence, format, size, and quality of ads that we display;

•	users have difficulty installing, updating, or otherwise accessing our products on mobile devices as a result of actions by us or third parties that we rely on to distribute our products and deliver our services;

•	user behavior on any of our products changes, including decreases in the quality and frequency of content shared on our products and services;

•	we are unable to continue to develop products for mobile devices that users find engaging, that work with a variety of mobile operating systems and networks, and that achieve a high level of market acceptance;

•	there are decreases in user sentiment about the quality or usefulness of our products or concerns related to privacy and sharing, safety, security, or other factors;

•	we are unable to manage and prioritize information to ensure users are presented with content that is interesting, useful, and relevant to them;

•	we are unable to obtain or attract engaging third-party content;

•	users adopt new technologies where our products may be displaced in favor of other products or services, or may not be featured or otherwise available;

•	there are adverse changes in our products that are mandated by legislation, regulatory authorities, or litigation, including settlements or consent decrees;

•	technical or other problems prevent us from delivering our products in a rapid and reliable manner or otherwise affect the user experience, such as security breaches or failure to prevent or limit spam or similar content;

•	we adopt terms, policies, or procedures related to areas such as sharing or user data that are perceived negatively by our users or the general public;

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•	we elect to focus our user growth and engagement efforts more on longer-term initiatives, or if initiatives designed to attract and retain users and engagement are unsuccessful or discontinued, whether as a result of actions by us, third parties, or otherwise;

•	we fail to provide adequate customer service to users, marketers, or developers;

•	we, developers whose products are integrated with our products, or other companies in our industry are the subject of adverse media reports or other negative publicity; or

•	our current or future products, such as our development tools and application programming interfaces that enable developers to build, grow, and monetize mobile and web applications, reduce user activity on our products by making it easier for our users to interact and share on third-party mobile and web applications.

•	decreases in user engagement, including time spent on our products;

•	our inability to continue to increase user access to and engagement with our mobile products;

•	product changes or inventory management decisions we may make that change the size, format, frequency, or relative prominence of ads displayed on our products or of other unpaid content shared by marketers on our products;

•	our inability to maintain or increase marketer demand, the pricing of our ads, or both;

•	our inability to maintain or increase the quantity or quality of ads shown to users;

•	changes to third-party policies that limit our ability to deliver or target advertising on mobile devices;

•	the availability, accuracy, and utility of analytics and measurement solutions offered by us or third parties that demonstrate the value of our ads to marketers, or our ability to further improve such tools;

•	loss of advertising market share to our competitors, including if prices for purchasing ads on Facebook increase or if competitors offer lower priced or more integrated products;

•	adverse legal developments relating to advertising, including legislative and regulatory developments and developments in litigation;

•	decisions by marketers to reduce their advertising as a result of adverse media reports or other negative publicity involving us, content on our products, developers with mobile and web applications that are integrated with our products, or other companies in our industry;

•	the degree to which users opt out of certain types of ad targeting;

•	the degree to which users cease or reduce the number of times they click on our ads;

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•	changes in the way advertising on mobile devices or on personal computers is measured or priced; and

•	the impact of macroeconomic conditions, whether in the advertising industry in general, or among specific types of marketers or within particular geographies.

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•	the popularity, usefulness, ease of use, performance, and reliability of our products compared to our competitors' products, particularly with respect to mobile products;

•	the size and composition of our user base;

•	the engagement of our users with our products and competing products;

•	the timing and market acceptance of products, including developments and enhancements to our or our competitors' products;

•	our ability to distribute our products to new and existing users;

•	our ability to monetize our products;

•	the frequency, size, format, quality, and relative prominence of the ads displayed by us or our competitors;

•	customer service and support efforts;

•	marketing and selling efforts, including our ability to measure the effectiveness of our ads and to provide marketers with a compelling return on their investments;

•	our ability to establish and maintain developers' interest in building mobile and web applications that integrate with Facebook and our other products;

•	our ability to establish and maintain publisher interest in integrating their content with Facebook and our other products;

•	changes mandated by legislation, regulatory authorities, or litigation, including settlements and consent decrees, some of which may have a disproportionate effect on us;

•	acquisitions or consolidation within our industry, which may result in more formidable competitors;

•	our ability to attract, retain, and motivate talented employees, particularly software engineers, designers, and product managers;

•	our ability to cost-effectively manage and grow our operations; and

•	our reputation and brand strength relative to those of our competitors.

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•	our ability to maintain and grow our user base and user engagement;

•	our ability to attract and retain marketers in a particular period;

•	fluctuations in spending by our marketers due to seasonality, such as historically strong spending in the fourth quarter of each year, or other factors;

•	the frequency, prominence, size, format, and quality of ads shown to users;

•	the pricing of our ads and other products;

•	our ability to maintain or increase Payments and other fees revenue;

•	the diversification and growth of revenue sources beyond advertising on Facebook;

•	the development and introduction of new products or services by us or our competitors;

•	increases in marketing, sales, and other operating expenses that we will incur to grow and expand our operations and to remain competitive;

•	our ability to maintain gross margins and operating margins;

•	costs related to acquisitions, including costs associated with amortization and additional investments to develop the acquired technologies;

•	charges associated with impairment of any assets on our balance sheet;

•	our ability to obtain equipment and components for our data centers and other technical infrastructure in a timely and

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•	system failures or outages, which could prevent us from serving ads for any period of time;

•	breaches of security or privacy, and the costs associated with any such breaches and remediation;

•	changes in the manner in which we distribute our products or inaccessibility of our products due to third-party actions;

•	fees paid to third parties for content or the distribution of our products;

•	share-based compensation expense, including acquisition-related expense;

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

•	changes in the legislative or regulatory environment, including with respect to privacy and data protection, or enforcement by government regulators, including fines, orders, or consent decrees;

•	the overall tax rate for our business, which may be affected by a number of factors, including the financial results of our international subsidiaries and the timing, size, and integration of acquisitions we may make from time to time;

•	tax obligations that may arise from changes in laws or resolutions of tax examinations that materially differ from the amounts we have anticipated;

•	fluctuations in currency exchange rates and changes in the proportion of our revenue and expenses denominated in foreign currencies;

•	fluctuations in the market values of our portfolio investments and in interest rates;

•	changes in U.S. generally accepted accounting principles; and

•	changes in global business or macroeconomic conditions.

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•	increased costs and diversion of management time and effort and other resources to deal with bad transactions or customer disputes;

•	potential fraudulent or otherwise illegal activity by users, developers, employees, or third parties;

•	restrictions on the investment of consumer funds used to transact Payments; and

•	additional disclosure and reporting requirements.

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•	political, social, or economic instability;

•	risks related to the legal and regulatory environment in foreign jurisdictions, including with respect to privacy, tax, law enforcement, content, trade compliance, intellectual property, and terrestrial infrastructure matters;

•	potential damage to our brand and reputation due to compliance with local laws, including potential censorship or requirements to provide user information to local authorities;

•	fluctuations in currency exchange rates and compliance with currency controls;

•	foreign exchange controls and tax regulations that might prevent us from repatriating cash earned in countries outside the United States or otherwise limit our ability to move cash freely, and impede our ability to invest such cash efficiently;

•	higher levels of credit risk and payment fraud;

•	enhanced difficulties of integrating any foreign acquisitions;

•	burdens of complying with a variety of foreign laws;

•	reduced protection for intellectual property rights in some countries;

•	difficulties in staffing, managing, and overseeing global operations and the increased travel, infrastructure, and legal compliance costs associated with multiple international locations;

•	compliance with the U.S. Foreign Corrupt Practices Act, the U.K. Bribery Act, and similar laws in other jurisdictions; and

•	compliance with statutory equity requirements and management of tax consequences.

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•	actual or anticipated fluctuations in our revenue and other operating results;

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

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

•	additional shares of our Class A common stock being sold into the market by us, our existing stockholders, or in connection with acquisitions, including shares sold by our employees to cover tax liabilities in connection with RSU vesting events, or the anticipation of such sales;

•	investor sentiment with respect to our competitors, our business partners, and our industry in general;

•	announcements by us or our competitors of significant products or features, technical innovations, acquisitions, strategic partnerships, joint ventures, or capital commitments;

•	announcements by us or estimates by third parties of actual or anticipated changes in the size of our user base, the level of user engagement, or the effectiveness of our ad products;

•	changes in operating performance and stock market valuations of technology companies in our industry, including our developers and competitors;

•	price and volume fluctuations in the overall stock market, including as a result of trends in the economy as a whole;

•	the inclusion or deletion of our Class A common stock from any trading indices, such as the S&P 500 Index;

•	media coverage of our business and financial performance;

•	lawsuits threatened or filed against us;

•	developments in anticipated or new legislation and pending lawsuits or regulatory actions, including interim or final rulings by tax, judicial, or regulatory bodies; and

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

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•	until the first date on which the outstanding shares of our Class B common stock represent less than 35% of the combined voting power of our common stock, any transaction that would result in a change in control of our company requires the approval of a majority of our outstanding Class B common stock voting as a separate class;

•	we have a dual class common stock structure, which provides Mr. Zuckerberg with the ability to control the outcome of matters requiring stockholder approval, even if he owns significantly less than a majority of the shares of our outstanding

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•	when the outstanding shares of our Class B common stock represent less than a majority of the combined voting power of common stock, certain amendments to our restated certificate of incorporation or bylaws will require the approval of two-thirds of the combined vote of our then-outstanding shares of Class A and Class B common stock;

•	when the outstanding shares of our Class B common stock represent less than a majority of the combined voting power of our common stock, vacancies on our board of directors will be able to be filled only by our board of directors and not by stockholders;

•	when the outstanding shares of our Class B common stock represent less than a majority of the combined voting power of our common stock, our board of directors will be classified into three classes of directors with staggered three-year terms and directors will only be able to be removed from office for cause;

•	when the outstanding shares of our Class B common stock represent less than a majority of the combined voting power of our common stock, our stockholders will only be able to take action at a meeting of stockholders and not by written consent;

•	only our chairman, our chief executive officer, our president, or a majority of our board of directors are authorized to call a special meeting of stockholders;

•	advance notice procedures apply for stockholders to nominate candidates for election as directors or to bring matters before an annual meeting of stockholders;

•	our restated certificate of incorporation authorizes undesignated preferred stock, the terms of which may be established, and shares of which may be issued, without stockholder approval; and

•	certain litigation against us can only be brought in Delaware.

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Item 1B.	Unresolved Staff Comments

Item 2.	Properties

Item 3.	Legal Proceedings

Item 4.	Mine Safety Disclosures

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

(1)	Unvested acquisition shares are subject to a right of repurchase by us in the event the recipient of such unvested acquisition shares is no longer employed by us. All shares in the above table were shares repurchased as a result of us exercising this right and not pursuant to a publicly announced plan or program.

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Item 6.	Selected Financial Data.

(1)	Total costs and expenses include $2.97 billion, $1.84 billion, $906 million, $1.57 billion, and $217 million of share-based compensation for the years ended December 31, 2015, 2014, 2013, 2012, and 2011, respectively.

(2)	See Note 3 of the accompanying notes to our consolidated financial statements for a description of our computation of basic and diluted earnings per share attributable to Class A and Class B common stockholders.

(1)

In November 2015, the FASB issued Accounting Standards Update No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes (ASU 2015-17), which simplifies the presentation of deferred income taxes by requiring deferred tax assets and liabilities be classified as noncurrent on the balance sheet. We early adopted this standard retrospectively and reclassified all of our current deferred tax assets to noncurrent deferred tax assets on our consolidated balance sheets data for all periods presented. As a result of the reclassifications, certain noncurrent deferred tax liabilities as of December 31, 2014, 2013, and 2012 were netted with noncurrent deferred tax assets.

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•	FCF does not reflect our future contractual commitments; and

•	other companies in our industry present similarly titled measures differently than we do, limiting their usefulness as comparative measures.

(1)

For the year ended December 31, 2012, net cash provided by operating activities was reduced by $451 million of income tax refundable from income tax loss carrybacks due to the recognition of tax benefits related to share-based compensation from restricted stock units granted prior to January 1, 2011. We received substantially all of this refund in 2013 which increased our net cash provided by operating activities and FCF for the year ended December 31, 2013.

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

•	Daily active users (DAUs) were 1.04 billion on average for December 2015, an increase of 17% year-over-year.

•	Mobile DAUs were 934 million on average for December 2015, an increase of 25% year-over-year.

•	Monthly active users (MAUs) were 1.59 billion as of December 31, 2015, an increase of 14% year-over-year.

•	Mobile MAUs were 1.44 billion as of December 31, 2015, an increase of 21% year-over-year.

•	Revenue was $17.93 billion, up 44% year-over-year (or 53% year-over-year on a constant currency basis), and ad revenue was $17.08 billion, up 49% year-over-year (or 59% year-over-year on a constant currency basis).

•	Total costs and expenses were $11.70 billion.

•	Income from operations was $6.23 billion.

•	Net income was $3.69 billion with diluted earnings per share of $1.29.

•	Capital expenditures were $2.52 billion.

•	Effective tax rate was 40%.

•	Cash and cash equivalents, and marketable securities were $18.43 billion as of December 31, 2015.

•	Headcount was 12,691 as of December 31, 2015.

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•	Daily Active Users (DAUs). We define a daily active user as a registered Facebook user who logged in and visited Facebook through our website or a mobile device, or used our Messenger application (and is also a registered Facebook user), on a given day. We view DAUs, and DAUs as a percentage of MAUs, as measures of user engagement.

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Mobile DAUs. We define a mobile DAU as a user who accessed Facebook via a mobile application or via mobile versions of our website such as m.facebook.com, whether on a mobile phone or tablet, or used our Messenger application (and is also a registered Facebook user) on a given day. We define a mobile-only DAU as a user who accessed Facebook solely through mobile applications or mobile versions of our website on a given day, whereas a mobile DAU may have also accessed Facebook on a personal computer on that day.

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•	Monthly Active Users (MAUs). We define a monthly active user as a registered Facebook user who logged in and visited Facebook through our website or a mobile device, or used our Messenger application (and is also a registered Facebook user), in the last 30 days as of the date of measurement. MAUs are a measure of the size of our global active user community.

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Mobile MAUs. We define a mobile MAU as a user who accessed Facebook via a mobile application or via mobile versions of our website such as m.facebook.com, whether on a mobile phone or tablet, or used our Messenger application (and is also a registered Facebook user) during the period of measurement. We define a mobile-only MAU as a user who accessed Facebook solely through mobile applications or mobile versions of our website during the period of measurement, whereas a mobile MAU may have also accessed Facebook on a personal computer during the period of measurement.

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(1)

Financing obligation - building in progress - leased facility represents our commitment to lease an entire office building in London, United Kingdom, that is currently under construction. As of December 31, 2015, $62 million of the total obligation was recorded as a liability and is included in other liabilities on our consolidated balance sheets. See Note 10 of the accompanying notes to our consolidated financial statements for additional information related to this financing obligation.

(2)	Other contractual commitments primarily relate to network infrastructure for our data center operations and, to a lesser extent, construction commitments related to our data center sites.

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Item 7A.	Quantitative and Qualitative Disclosures About Market Risk

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Item 8.	Financial Statements and Supplementary Data

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Note 1.	Summary of Significant Accounting Policies

•	persuasive evidence of an arrangement exists;

•	delivery of our obligations to our customer has occurred;

•	the price is fixed or determinable; and

•	collectability of the related receivable is reasonably assured.

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Note 2.	Acquisitions

Note 3.	Earnings per Share

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Note 4.	Cash and Cash Equivalents, and Marketable Securities

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Note 5.	Fair Value Measurement

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Note 6.	Property and Equipment

Note 7.	Goodwill and Intangible Assets

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Note 8.	Liabilities

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(1)

In November 2015, the FASB issued ASU 2015-17, which simplifies the presentation of deferred income taxes by requiring deferred tax assets and liabilities be classified as noncurrent on the balance sheet. We early adopted this standard retrospectively, and as a result of the reclassifications, certain noncurrent deferred tax liabilities were netted with noncurrent deferred tax assets. See Note 1 in these notes to the consolidated financial statements for additional information.

Note 9.	Long-term Debt

Note 10.	Commitments and Contingencies

(1)

In 2015, we entered into an agreement to lease an entire office building in London, United Kingdom, that is currently under construction. As a result of our involvement during the construction period, we are considered to be the owner of the construction project for accounting purposes. The above financing obligation, building in progress - leased facility represents the total expected financing and lease obligation associated with this lease and will be settled through monthly

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Note 11.	Stockholders' Equity

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(1)	The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock option awards and the official closing price of our Class A common stock, as reported on the NASDAQ Global Select Market, of $104.66 on December 31, 2015.

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(1)	Unvested shares include inducement awards issued in connection with an acquisition in 2014 and are subject to the terms, restrictions, and conditions of separate non-plan RSU award agreements.

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Note 12.	Interest and other income/(expense), net

Note 13.	Income Taxes

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Note 14.	Geographical Information

(1)	No individual country, other than disclosed above, exceeded 10% of our total revenue for any period presented

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

Item 9A.	Controls and Procedures

Item 9B.	Other Information

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Item 10.	Directors, Executive Officers and Corporate Governance

Item 11.	Executive Compensation

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

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

Item 14.	Principal Accounting Fees and Services

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Item 15.	Exhibits, Financial Statement Schedules

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