Facebook Inc.'s 6.3 percent drop yesterday, after the end ofrestrictions on share sales by its biggest investors, was thesecond-largest post-lock-up decline among companies that have gonepublic since January 2011.

Only social-game maker Zynga Inc. tumbled more, losing 7.9percent, on the first day that insiders could start selling theirstakes, data compiled by Bloomberg show. That was the largestone-day post-lock-up descent among the 20 biggest initial publicofferings since January 1, 2011. The slump yesterday left MenloPark, California-based Facebook at a record low after a 60 percentincrease in the number of shares available for trading.

Under restrictions worked out with IPO underwriters, earlyinvestors agree not to sell their holdings for a preset periodafter a market debut to keep from flooding the market with shares.Facebook's decline reflects concern that more sales will follow inthe coming months as additional lock-ups expire and as the companystruggles to wring sales from a growing customer base, said RoryMaher, an analyst at Capstone Investments Inc.