Facebook shares have lost more than half of their value since their initial public offering three months ago.
The stock slid 7 cents to 18.98 dollars (£12.08) in trading. Earlier, it hit 18.75 dollars, a new low. The social networking site's much-anticipated IPO turned sour amid technical problems on the NASDAQ stock market and high expectations. The stock has not surpassed its 38 dollar (£24.19) IPO price since its first trading day.
Investors are worried about Facebook's ability to grow revenue quickly, especially when it comes to garnering mobile advertising dollars as users flock to smartphones and tablet computers.
There are also looming expirations of the IPO lock-up periods. Lock-ups preventing many Facebook employees from selling stock expire this autumn, potentially flooding the market with more shares.