Shares in the social networking company ended their first day flat, after an initial surge to $43 (£27).
The company has a host of high-profile investors, including Apple (NasdaqGS: AAPL - news) co-founder Steve Wozniak and U2 frontman Bono, and more than 500 million shares exchanged hands on the stock's first day of trading.
The Nasdaq exchange has apologised for a glitch in its system affected trading in newly-issued Facebook shares on Friday.
The US stock exchange is planning to revamp its technology systems that handle IPOs after trading in Facebook shares was delayed by half an hour as the company went public and investors were left unaware for hours as to whether their buy and sell orders had been executed.
With shares at $38 (£24) a piece, the company was valued at $104bn (£66bn) on Friday, making it more valuable than Amazon, Disney (NYSE: DIS - news) , McDonalds or the Ford Motor Company.
Facebook has more than 900 million active users globally who log in at least once a month. But the firm makes only a tiny proportion of its income from its users - mainly through advertising.
The founding of the social networking site by Mark Zuckerberg in a Harvard dorm room was made into a film in 2010.
http://uk.finance.yahoo.com/news/facebook-shares-fall-below-ipo-133830402.html