Facebook stock rebounds after dropping below $19

Facebook Inc. hit a new low of $18.75 before bouncing back to $20.01 by the time the stock market closed. That's up 96 cents, or 5 percent, for the day.

The social networking icon's much-anticipated IPO turned sour amid technical problems on the Nasdaq stock market and high expectations. The stock has not surpassed its $38 IPO price since its first trading day.

Investors are worried about Facebook's ability to grow revenue quickly, especially through mobile advertising as users flock to smartphones and tablet computers. There are also looming expirations of the IPO lock-up periods. Lockups preventing many Facebook employees from selling stock expire this fall, potentially flooding the market with more shares.