By Gerry Shih
SAN FRANCISCO, July 31 (Reuters) - Facebook Inc's (FB.O) shares dived 6 percent to another record low on Tuesday, sliding for the third straight day since a lackluster quarterly report showed decelerating user growth.
Investors have punished the stock of the No. 1 social network and other consumer-focused Internet companies such as Zynga Inc, questioning their ability to sustain growth and maintain lofty valuations. Last week, Facebook reported results but offered no outlook or forecast for the year, spooking investors who sought reassurance about growth in 2012.
Wall Street is also bracing for a potential deluge of millions of shares after Aug. 16, when a post-IPO lockup period on employee share sales expires.
Despite having shed 40 percent of its value since a May 18 IPO, Facebook still trades at about 47 times forward earnings, versus Google Inc's (GOOG.O) 15 times.
On Tuesday, Bernstein Research analyst Carlos Kirjner upgraded Facebook to market perform, but estimated the lockup's expiry could unleash up to 211 million shares.
He valued Facebook's core display business at just $19 a share. But he said the company's potential around its innovative social graph was worth a $4 premium. Bernstein set Facebook's 12-month target price at $23.
The size of the current float could be nearly tripled by November, as more and more employees begin to sell, Kirjner warned.
Facebook stock was off 5.8 percent at $21.81 in afternoon trade.
(Reporting By Gerry Shih; Editing by Alden Bentley)