In an announcement that Facebook hopes will be “liked” by many, the world’s largest social network filed to become a publicly listed company late Wednesday. Documents filed with the U.S. Securities and Exchange Commission provide investors and Facebook users the first public glimpse of the company’s financial state, technological challenges, and ambitions.

In its S-1 filing, Facebook said it is trying to raise $5 billion through an initial public offering of shares, which would make it the biggest Internet IPO to date. The stock will trade on either the Nasdaq Stock Market or New York Stock Exchange, most likely under the ticker symbol “FB.” The $5 billion figure may change by the time Facebook’s stock begins trading— something that typically happens several months after a company files its registration statement.

A company’s S-1 filing contains details of the company’s financials and statements about its goals, assets, and any potential dangers to the business. Technology Review read Facebook’s and found these interesting tidbits:

• A total of 845 million people used the site every month, as of the end of 2011—an increase of 39 percent over 2010. A total of 483 million people used Facebook daily, as of the end of 2011—an increase of of 48 percent compared with the same period a year earlier.
• Facebook is making money. The company reported in its filing that its net income totaled $1 billion in 2011, compared with $606 million in 2010. In 2011, revenue rose 85 percent to $3.7 billion. Mobile use of Facebook is big, and getting bigger. In December, over 425 million of the company’s monthly active users accessed Facebook through a mobile device, such as a phone or tablet. The company expects its ranks of mobile users to grow faster than its active monthly user count “for the foreseeable future,” partly because it is so focused on getting more mobile users. Facebook doesn’t currently bring in much revenue from its mobile apps, though, so it will need to find ways to change that as this growth continues.
• Facebook is concerned about its dependence on Apple’s iOS software and Google’s Android operating system, which power mobile phones and tablets, saying that its mobile growth depends on its apps being able to work on those platforms. The social network said that it would suffer if Apple of Google made changes that hinder the functionality of its mobile apps or favor competitors.
• Last year, 12 percent of Facebook’s revenue came from one source: Online games company Zynga, which itself went public in December. This revenue, which comes from the sale of virtual goods in Zynga’s games and ads Zynga bought, is up from less than 10 percent in 2010 and 2009. Having such a large chunk of revenue come from a single source could concern investors, because if Facebook’s relationship with Zynga sours it could significantly hurt Facebook’s financials. Zynga’s own S-1 filing noted its dependence on Facebook as a risk.
• In a letter to investors contained in the filing, founder and CEO Mark Zuckerberg, 27, said that his company doesn’t “build services to make money; we make money to build better services.” He also noted the company’s “Hacker Way” culture and management style, which involves constantly improving and iterating.
  
• Facebook’s headcount rose to 3,200 as of December 31, from 2,127 a year earlier. The company expects this growth to continue, and said it plans to hire a “significant” number of engineers and salespeople this year.
• The company, which last year opened its first data center to cut the cost of the computing power required to run its website, has big plans to ramp up its infrastructure spending and to design and own more data centers. This is a complicated undertaking, though, and the company warned that any issues could raise anticipated costs and hurt its user experience.
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