Google Incorporated, owner of the most-used Internet search engine, posted fourth-quarter profit that missed analyst estimates, snapping a streak that has propelled the stock since it went public in 2004.

The shares plunged 17% after the company’s 82% rise in net income disappointed investors seeking justification for a stock price that has more than doubled in a year. Today’s earnings are the first time Mountain View, California-based Google has missed estimates in six quarters.

The results represent a rare misstep for Google, whose advertising revenue linked to search results has given it a market value greater than Coca-Cola Co. and Cisco Systems Inc.

Google’s larger-than-expected spending on marketing and a jump in the company’s tax rate weighed on profit. Sales rose 86% to $1.92 billion, meeting estimates.

“There might be some realization that they are in the advertising business, not the rocket-ship business,” said Jane Snorek, who helps manage $110 billion, including Google shares, at US Bancorp Asset Management in Milwaukee.

Net income rose to $372.2 million, or $1.22 a share, from $204.1 million, or 71 cents, a year earlier, Google said today. Profit, excluding one-time items, was $1.54 a share, short of the $1.78 prediction of Jefferies & Co.’s Youssef Squali.

Google shares, up 31% in the fourth quarter alone, tumbled $72.38 to $360.28. They earlier rose $5.84 to $432.66 at 4 p.m. New York time in Nasdaq Stock Market composite trading.

The shares have surged since being sold at $85 in August 2004 and given Google a market value that stood at $128 billion yesterday.

“They have been handily been beating all of the estimates,” an analyst at Oppenheimer & Co. in Boston, Sasa Zorovic, said, who has a “buy” rating on the shares. “This is now the first time that this tradition at Google has been broken. The aura now is a thing of the past at Google.”

Mr. Squali, whom StarMine Corporation ranks among the most accurate Internet analysts, was 2 cents above the average $1.76 profit estimate of 31 analysts surveyed by Thomson Financial. Revenue, after sales passed on to other Web sites, doubled to $1.29 billion, matching analysts’ estimates.

“On the top line they did fairly well,” Zorovic said. “On the bottom line, it sure is a miss.”

Chief Financial Officer George Reyes said higher taxes caused the profit shortfall. The tax rate rose to 41.8% from 31% in the third quarter. International businesses contributed 38% of sales.