U.S. stocks fell for a second day on Tuesday, after a batch of disappointing results was released, including microchip maker Texas Instruments Inc, health insurer UnitedHealth Group Inc and Coach Inc., which increased concerns about the health of the economy.

Apple Inc. also fell for the first time in seven days after the maker of its popular iPhone handset, American Technology Research, said it may not beat earnings estimates enough to increase the stock.

The Standard & Poor's 500 Index declined 8.93 points, or 0.6 percent, to 1,379.24 at 11:23 a.m. in New York. The Dow Jones Industrial Average slipped 76.05, or 0.6 percent, to 12,748.97. The Nasdaq Composite Index decreased 16.97, or 0.7 percent, to 2,391.07.

Texas Instruments reported higher quarterly earnings that met estimates on Monday. The company warned that its second quarter would be weaker than expected due to an uncertain economic situation, citing weaker demand for high-end cell phones. The company's shares fell 2 percent to $28.63

Meanwhile, UnitedHealth Group Inc, the biggest U.S. medical insurer, tumbled on forecasts that trailed estimates. The company posted a lower-than-expected first-quarter profit as sales to employers and individuals wavered causing the group to slash its full-year earnings forecast. Its shares tumbled 10.2 percent to $33.96.

McDonald's Corp, part of the Dow Jones Industrial Average, beat analyst expectations by posting quarterly profit above expectations, said it earned $946.1 million or 81 cents a share, up from $762.4 million or 62 cents in the first quarter of 2007.

The Oak Brook, Ill.-based franchise citied stronger overseas sales, but its shares dropped 0.3 percent to $58.51, after the company noted sales fell slightly in March at U.S. restaurants open at least 13 months.

Coach, the largest U.S. maker of luxury leather handbags, dropped after retailers discounted products. The company declined $1.42 to $31.08.