Facebook dropped 6.2 per cent to a record low, the third straight day of declines after the world's largest social-networking service reported second-quarter results that showed slowing growth.
Shares slumped to US$21.71 yesterday as of the close in New York, the lowest closing price since Facebook held an initial public offering on May 17.
Facebook disappointed investors last week when it reported sales growth of 32 per cent, down from 45 per cent in the first quarter, and refrained from providing a sales or profit outlook for the year.
The company also posted slower user growth and is grappling with concerns about how well it can boost advertising on mobile devices.
"There were obviously some people who didn't want to sell on the first day in anticipation that you would see some stabilisation and the stock price sort of return a little bit," said Mark Harding, an analyst at JMP Securities who has a market outperform rating on the stock.
"Perhaps they're disappointed by the lack of a recovery, and maybe now they're using the opportunity to perhaps pare back."
Facebook has lost 43 per cent since the IPO.
Carlos Kirjner, an analyst at Sanford C. Bernstein & Co, lowered his Facebook price target by US$2 to US$23 a share even as he upgraded the stock to a market perform from an underperform.
Facebook is worth US$19 a share, based on its value as an online-display ad company that's gaining market share, he said.
Growth opportunities, including new advertising markets, add another US$4 to the stock price, Kirjner said.
Facebook shares could fall in the coming months with the expiry of lockup periods, which bar insiders from selling shares for a period after the IPO, Kirjner said. More than 200 million shares will come on the market in August alone, he said.
Facebook on July 26 reported revenue of US$1.18 billion, topping an estimate of US$1.16 billion, according to Bloomberg.