New York - Facebook shares sunk over 6% by the midway point of trade on Thursday after a freeze on insiders selling shares was lifted.
By 16:00 GMT the stock stood at $19.90 a piece, almost half the $38 offering price when the company listed in May.
"Starting today, 271 million more shares may be traded on the open market," said analysts at Briefing.com
"Pressure caused by today's selling has dropped the shares of the social media company to an all-time low since its May IPO."