Facebook's stock hit a record low Friday, sinking to just over half the IPO price, as insiders and the first investors in the company became eligible to unload the shares "locked up" by federal trading restrictions since the commencement of sales. Experts said in response to the drop that the value of the stock and company could plummet further if early purchasers and employees saturate the market with their shares of stock as more lockups expire before the end of the year.