Web search leader Google Inc. (GOOG) Thursday said its quarterly profit more than quadrupled, fueled by growth in online search advertising, but shares fell 6.5 percent as revenue was not as strong as some had hoped.

Google posted second-quarter net profit of $342.8 million, or $1.19 a share. The company, which has been publicly held since mid-August, had a net profit of $79.1 million, or 30 cents per share, in the year-earlier period.

Shares of Google rose initially in extended trading on the Inet electronic brokerage network (search), then dropped to $293.40 from its Nasdaq close of $313.94, a record high close.

Google's revenue was a little better than published expectations, but there "was not as much upside as some had hoped," said Marianne Wolk, Internet analyst at Susquehanna Financial Group.

Revenue, which comes almost exclusively from Web search advertising, was $1.38 billion, compared with $700.2 million in the year-ago period.

Analysts had forecast net earnings on average of $1.12 per share, within a range of 98 cents to $1.27, according to Reuters Estimates. Revenue was estimated at $1.32 billion.

Google paid out $494 million of quarterly revenue in fees, referred to as traffic acquisition costs, to sites that carry its ads.

Excluding the effect of stock options, Google's profit would have been $1.29 to $1.35 per share. On that basis, analysts had predicted $1.23 per share, within a range of $1.12 to $1.37.

Google's stock options expenses are significantly higher than its peers because it recently went public, but those expenses are declining over time.

Google has expanded its services beyond Web search to free e-mail, Web logs, video search and comparison shopping, but search advertising remains its key revenue driver.

Google currently trades at about 59 times its projected 2005 net earnings per share while rival Yahoo Inc. (YHOO) trades at about 56 times its estimated 2005 net earnings per share.