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.