Web search leader Google Inc. (search), in its first earnings report as a publicly held company, on Thursday posted quarterly net income and revenue that more than doubled on strong Web search advertising.  

Google shares were volatile after the company reported results, falling at first and then rising nearly 8 percent in after-hours trade. Analysts' estimates varied widely, and Google has said it will not issue financial forecasts.

"They were exceptional. They really surpassed most people's expectations by a really wide margin," said Marianne Wolk, an analyst with independent Susquehanna Financial Group (search).

Google, based in Mountain View, California, had net income of $52.0 million, or 19 cents a share, in the third quarter, up from $20.4 million, or 8 cents a share, a year earlier.

Revenue jumped to $805.9 million from $393.9 million.

Excluding the cost of a legal settlement with rival Yahoo Inc. (search) and other items, Google had a profit of $125 million, or 45 cents a share.

Wolk said if the company were also to exclude the cost of stock-based compensation, it would have earned 70 cents a share.

That compared with analysts' calls for a profit before items of 56 cents per share — within a range of 52 cents to 61 cents a share — on revenue of $751.7 million, according to figures compiled by Reuters Estimates.

Google, which sold shares in a $1.67 billion initial public offering in August, said before the debut of its stock that it would not issue financial forecasts, and it said so again on Thursday.

"We're not going to be offering future guidance today," Google Chief Executive Eric Schmidt said on a conference call with analysts to discuss results.

Google and rival Yahoo each get a significant portion of their revenue from Web search advertisements, a lucrative and fast-growing market.

Elsewhere, software giant Microsoft Corp. has made big investments in Web search and has made no secret of its intent to enter the market Google now dominates.

Google has moved into e-mail, a core business for both Yahoo and Microsoft. It also operates a comparison-shopping search engine called Froogle and recently announced a test of a new desktop search product — a move many analysts saw as a direct shot at Microsoft.

Google shares, which closed at $149.38 on the Nasdaq, rose to $160.80 in extended trade.