Shares of the social media giant plunged as the post-IPO lock-up period ended, allowing early investors to sell their shares and making more than 271 million new shares eligible for trading.
The stock hit a low of $19.69 -- down $1.20, or 6 percent.
Facebook opened at $38 a share in May. The first day of trading was marred by a Nasdaq computer glitch, and then an unimpressive earnings report followed, causing the stock to spiral downward.
Facebook stock was trading at just under $20 in early afternoon trading in New York.
