NEW YORK (AP) - Facebook's stock plunged to an all-time low Thursday after the expiration of a lock-up period that has provided some early investors and insiders with an opportunity to exit.
Firms ranging from Accel Partners to Goldman Sachs, Zynga CEO Mark Pincus and Facebook board members James Breyer, Peter Thiel and Reid Hoffman are among those free to sell stock they own.
Microsoft Corp., an early Facebook investor, is another one, though it's unlikely to sell because of partnerships it has with social-networking leader.
It's not yet known whether anyone had sold shares. The stock price decline could reflect investors' anticipation of such a move.
It's conceivable no one would sell those extra shares, but if too many do, Facebook's stock could decline because the market would be flooded with additional shares.
Facebook Inc.'s stock traded as low as $19.69 before bouncing back to $19.99 in Thursday morning trading.
That's still nearly 6 percent down, or $1.21, from Wednesday's close and about 48 percent below its initial public offering price of $38. If the stock hits $19, it will have lost half its value since Facebook went public in May.
It's been a rough run for Facebook. After one of the most-anticipated IPOs in history, Facebook suffered what may be the most-botched public offering as trading glitches marred its first day.
It's been almost all downhill for the Menlo Park., Calif., company since then. Investors have been concerned about Facebook's ability to keep increasing revenue and make money from its growing mobile audience, even as many analysts hold positive long-term views.
Those eligible to sell additional shares Thursday were the investors and directors who had participated in the May IPO. The exception was CEO Mark Zuckerberg, who will be ineligible until November. Other shareholders, including many Facebook employees, will be able to sell beginning in October.
The last lockup period expires next May, a year after the IPO. In all, up to 1.91 billion more shares could flood the stock market over the next several months - more than four times the 421 million shares that have been trading since Facebook's IPO.
Of the 1.91 billion, 271 million shares became eligible for sale Thursday.