U.S. consumer sentiment stumbled for the first time in five months in early February, market sources said on Friday, as a struggling stock market and lingering pessimism about the economy dented Americans' hopes for a vigorous recovery.

The University of Michigan's preliminary February consumer sentiment index fell to 90.9 from 93.0 in January, bucking consensus forecasts of a rise to 93.4. The report is released directly to subscribers only.

Watched closely by economists and investors, sentiment can give clues on future consumer spending, which underpins two-thirds of the U.S. economy. American consumers have consistently surprised forecasters by spending through the current recession, despite a sharp fall in business spending.

Amid mounting evidence that the economy is beginning to improve, stocks came under pressure in early February amid concerns about Corporate America's accounting practices. That dented some growing optimism for a strong recovery from recession, analysts said.

"With the stock market and 'Enronitis', they cause a lot of consumers to be a little cautious here," said Wayne Ayers, chief economist at FleetBoston Financial. "We are in the beginning of a recovery but it's going to be tepid one."

The report followed news on Wednesday that retail sales nationwide rose by 1.2 percent in January excluding automobile sales, taking many by surprise.

U.S. Treasuries surged after the Michigan sentiment report was released, since it underscored concerns that a recovery could be slow and arduous, which could prompt the Federal Reserve to keep interest rates low for some time. Stocks fell after the report, but the dollar, slightly firmer on the day, was undeterred.

The University's current conditions index, which measures consumers' attitudes about their present financial situation, rose to 97.2 in early February from 95.7. This component of the index has remained trapped in a range for months as a weak job market and sluggish income growth have weighed on consumers.

The expectations index, which tracks attitudes about the year ahead, fell to 86.8 in February from 91.3 in January, when it surged 12 points. But it remained far above a reading of 75.5 in October after the Sept. 11 attacks.

The consumer sentiment survey is based on telephone interviews with roughly 500 Americans across the country on personal finances, business conditions and buying conditions. The preliminary index tracks about 250 of those 500.