Zynga files for IPO

After months of anticipation, Zynga is going public. The social game giant today filed its Form S-1 with the Securities and Exchange Commission, proposing an initial public offering of stock in the company. There are still details yet to be determined, like how many shares will be sold and for how much.

Zynga is the creator of the wildly popular casual games FarmVille, CityVille, and Mafia Wars, which are played on the Facebook social network. CNBC expects the game company's public offering to be huge, in the range of $15 billion to $20 billion. Previously, the privately held company was valued at $10 billion--more than megapublisher Electronic Arts' market capitalization.

For 2010, Zynga reported revenues of more than $597 million, up dramatically from 2009's $121 million and $19 million in 2008. Last year was also the first profitable campaign for the company, which declared a net income of nearly $91 million after losses of $53 million and $22 million in 2009 and 2008, respectively. The company's games also boast a cumulative user base of 232 million active players a month.

As part of the filing, Zynga also reported a wealth of risk factors to its business. Chief among those is that if the company fails to remain on good terms with Facebook, its business could suffer. Among the other concerns cited are the company's still-evolving business, dependence on "a small percentage of players for nearly all our revenue," and relatively low barriers to entry for those who would seek to compete in the social gaming space.

In April, Zynga hired away EA's COO John Schappert. The company is also negotiating with the city of San Francisco for an exemption to a payroll tax that affects payments gleaned from IPOs.