Disappointing earnings news and ambivalent economic reports joined forces Friday, causing investors to bail out of U.S. stock markets.

The Nasdaq fell 179.23, or nearly 5 percent, to 3,663. The Standard & Poor's 500 index dropped 29.73 to 1,419.89. The Dow Jones industrial average fell 74.96 to close at 10,511.17, led by Intel, which closed down $7.88 at $129.13. Microsoft rose 31 cents to $69.69. The Nasdaq closed down nearly 11 percent from its close of 4,094.45 last Friday. The Dow slipped 2 percent for the week, and the S&P 500 fell 4 percent. Unimpressive earnings news topped investor concerns. Big companies such as Lucent, Nokia and Ericsson have all recently warned investors that growth in the second half of the year may slow down. Several technology companies in the past two weeks have warned that parts shortages caused by voracious consumer demand will trim revenues for the remainder of the year. "People are starting to look toward future earnings, and that's what the market is reacting to today," said Tony Crooks, an analyst at First Call/Thomson Financial. Of the 78 technology companies in the S&P 500, 64 have reported earnings so far. Total earnings from those companies have grown 44 percent from last year's second quarter.