Social networking site Facebook is likely to file an IPO by the first quarter of 2012, with a valuation of over USD 100 billion, a media report said.

Facebook is likely to go public by next spring, CNBC quoted people familiar with the matter as saying.

"The company's IPO, were it to happen by next spring, would probably be triggered by a section of the 1934 Securities and Exchange Act known as 'the 500 rule'," which mandates that once a private company has more than 500 investors, it must begin releasing quarterly financial information to the Securities and Exchange Commission, just as public companies do, the report said.

Facebook has indicated that it expects to cross the 500-investor threshold this year. (PTI)