U.S. stocks fell on Monday as a resurgent U.S. dollar took a toll on commodity prices and investors paused to gauge if the outlook for corporate profits justified the market's recent run to 11-month highs.

Caterpillar Inc , down 2.5 percent, was among the top drags after the maker of bulldozers, excavators and other products said worldwide August sales of machinery to dealerships fell.

Crude oil futures shed 3.5 percent to $69.48 a barrel and spot gold prices dropped below $1,000 an ounce. The S&P materials <.GSPM> index fell nearly 2 percent.

Shares of Exxon Mobil Corp declined 1 percent to $69.26, while gold miner Newmont Mining Corp shed 3.1 percent to $43.55.

The Dow Jones industrial average <.DJI> lost 55.85 points, or 0.57 percent, to 9,764.35. The Standard & Poor's 500 Index <.SPX> declined 6.64 points, or 0.62 percent, to 1,061.66. The Nasdaq Composite Index <.IXIC> dipped 6.77 points, or 0.32 percent, to 2,126.09.

The Nasdaq's losses were curbed by a rise in shares of biotechnology companies after a brokerage raised its rating on Celgene Corp , up 3.6 percent at $54.46.

Through Friday, the benchmark S&P 500 <.SPX> had risen 58 percent since hitting a 12-year closing low in early March, partly because of strong second-quarter earnings and optimism that an economic recovery is gaining traction.

That optimism is beginning to come under some strain, however, as investors seek more clarity about the 2010 profit outlook and await hints of how strong results will be for the rest of this year.

Computer maker Dell Inc announced a $3.9 billion proposed takeover of Perot Systems Corp
. Perot Systems shares jumped 65.4 percent to $29.64, while Dell shares dipped 3.2 percent to $16.15.

Any benefit from that announcement, however, was tempered by the rising U.S. dollar. The dollar index, which measures the greenback against a basket of major currencies, rose 0.7 percent. <.DXY>

(Editing by Padraic Cassidy)