U.S. stocks fell on Friday as disappointing results from Microsoft and American Express curbed sentiment a day after a rally took the Dow industrials <.DJI> above the key 9,000 mark.

Shares extended losses after a gauge of consumer sentiment fell in July, roughly in line with analysts' expectations.

Microsoft Corp shares tumbled 9 percent, a day after the world's top software maker posted a steeper-than-expected 17 percent drop in quarterly revenue. That was a shift after the technology sector had seen shining results from bellwethers like Intel Corp and Apple Inc.

The technology sector of the S&P 500 <.GSPT> dropped 1.5 percent, weighing the most on the broader index.

American Express Co and fellow credit card issuer Capital One Financial Corp said rising customer delinquencies reduced second-quarter earnings.

AmEx shares dropped 1.5 percent to $29.01, and the S&P financial sector index <.GSPF> fell 1.4 percent.

The Dow Jones industrial average <.DJI> dropped 51.24 points, or 0.56 percent, to 9,018.05. The Standard & Poor's 500 Index <.SPX> fell 8.01 points, or 0.82 percent, to 968.28. The Nasdaq Composite Index <.IXIC> lost 35.49 points, or 1.80 percent, to 1,938.11.

The market is overbought, and it's almost looking for an excuse to correct, said Doug Roberts, chief investment strategist at Channel Capital Research in Shrewsbury, New Jersey.

It's almost that this (consumer data) is a bit of an excuse. It's combined with the earnings disappointment by Microsoft and American Express last night.

U.S. consumer confidence waned in late July to its lowest reading since April as tracked by the Reuters/University of Michigan Surveys of Consumers, on growing pessimism about the long-term economic outlook.

Amazon.com shares fell 7.6 percent to $86.72 a day after the Internet retailer reported revenues that missed analyst estimates.

Winding down a week loaded with quarterly reports, Schlumberger Ltd shares fell 3.1 percent to $55.98 after posting a sharp drop in earnings and warning it did not expect any rebound in spending by its oil- and gas-producing customers this year.

U.S. Treasury Secretary Timothy Geithner said Friday he was willing to work with lawmakers on shaping an overhaul of financial regulations but insisted major changes are necessary.

Geithner, Federal Reserve Chairman Ben Bernanke and Federal Deposit Insurance Corp Chairman Sheila Bair are testifying before the U.S. House Financial Services Committee on regulatory reform.

The S&P 500 <.SPX> closed Thursday at its highest since the Election Day in November. The Nasdaq <.IXIC> has risen for 12 straight days, its longest run since 1992.

(Reporting by Rodrigo Campos; additional reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)