Google "recession."

No one—except maybe I.B.M.—is immune to the economic slump gripping the nation. Now even Google, whose growth has seemed unstoppable, may be facing some significant headwinds if the reaction of investors is any indication.

Google reported strong second-quarter results, but its earnings fell short of forecasts while its revenue number only slightly topped the consensus estimate. Shares of Google tumbled 10 percent in after-hours trading.

The disappointment over Google may heighten fears that the economic downturn is deepening and causing advertisers to cut back on internet spending, as well as on print and television.

Such fears were fanned earlier today when ValueClick, an online advertising services agency and competitor to Google's DoubleClick, blamed the economic downturn for weak advertising spending.

Google said paid clicks grew 19 percent in the quarter from a year ago and fell 1 percent from the first of the year.  Google has 62 percent of the search market, according to ComScore, nearly double the share of Yahoo.

For the quarter, Google earned $1.25 billion, or $3.92 per share, up 35 percent from $925 million, or $2.93 per share in the quarter a year earlier. Excluding stock-based compensation costs, Google earned $4.63 per share, short of Wall Street estimates.

Sales, when the revenue that is passed on to partner sites is excluded, rose 43 percent to $3.9 billion, in line with forecasts.

"Strong international growth as well as sustained traffic increases on Google's Web properties propelled us to another strong quarter, despite a more challenging economic environment," said Eric Schmidt, chief executive of Google. "As we continue to focus on innovating in our core business of search, ads and apps, we also look forward to enhancing the experience of our users and expanding the reach of our advertisers and partners with new technologies and formats, particularly as our integration of DoubleClick gains momentum and creates new opportunities in display advertising and elsewhere."