Net income rose to $52 million, or 19 cents a share, from $20.4 million, or 8 cents, in the year-earlier quarter, the Mountain View-based company said. Revenue more than doubled to $805.9 million from $393.9 million, Google said in its first earnings report as a public company.

Revenue rose more than analysts had forecast and profit margins widened as Google fended off competition from Yahoo Inc., the second-most used search site. The two companies are trying sell more ads next to Internet search results, a $3.93 billion market in the U.S.

"Revenue growth was very powerful and because of the revenue growth, you can tell that the company is certainly continuing to maintain market share versus Yahoo," said Barry Randall, who manages about $100 million in stocks in U.S. Bancorp Asset Management's First American Technology Fund. Randall bought Google shares in the company's initial public offering in August.

Revenue excluding "traffic acquisition costs," fees that Google pays to other Web sites that display ads it sells, was $503 million. That was more than the average estimate of $456.3 million from 17 analysts.

Excluding a non-cash charge of $201 million to settle a contract dispute with Yahoo and some other expenses, Google said it would have earned $125 million, or 45 cents a share. That was less than the average estimate of 56 cents a share from 17 analysts surveyed by Thomson Financial.

Google's operating profit margin excluding the Yahoo settlement was 26.3 percent, compared with 16.9 percent a year ago.

Google shares, rose $12.06, or 8.1 percent, to $161.44 at 6:02 p.m. New York time in extended trading. Earlier, the stock rose $8.89 to $149.38 at 4 p.m. New York time in Nasdaq Stock Market composite trading.

The stock has risen 76 percent from Google's Aug. 18 initial public offering through the Nasdaq close Thursday, giving it a market value of $40.9 billion.