Facebook shares were down 15 percent to just below $23 in trading Friday after the company's lack of a financial forecast reinforced concerns about its mobile strategy, which will result in rapid cash burn in the near term.
The decline pulled the stock to its lowest price since its IPO in mid-May.
The social network, which reported its first quarterly results as public company on Thursday, managed to just beat revenue expectations.
"Based on the aftermarket reaction to the earnings it appears that investors wanted more than a slight beat," Piper Jaffray & Co analysts said in a client note.
Investors who have been worried about how the social network would make money from mobile advertising had also hoped that the company would signal that revenue growth was picking up.
JPMorgan Securities analysts said the stock could also be coming under pressure because of a lock-up expiring on August 19 when some early investors will be able to sell their shares, flooding the market with stock.
Reuters contributed to this report.