On Thursday, the market soared 3 percent after a long-awaited agreement was struck to help contain Europe's two-year debt crisis. The S&P 500 is up more than 13 percent this month, on pace for its biggest monthly gain since October 1974.
But investors remained skeptical over the debt deal as many details were still to be worked out before the region can show its ability to contain the crippling crisis.
"The rally really started even before we got the news from Europe. There is a strong (upside) bias in the market and people are acting on that basis," said Stanley J.G. Crouch, who oversees $2 billion as the chief investment officer of Aegis Capital in New York.
"But I think we have a long way to go with this (European debt) mess. I still see huge risks," he said.
The Dow Jones industrial average was down 21.64 points, or 0.18 percent, at 12,186.91. The Standard & Poor's 500 Index was down 5.93 points, or 0.46 percent, at 1,278.66. The Nasdaq Composite Index was down 11.62 points, or 0.42 percent, at 2,727.01.
The latest economic data showed U.S. consumer sentiment improved in October for the second month in a row as consumers felt more upbeat about the economy's prospects.
In earnings news, shares of Merck & Co Inc rose 1.8 percent to $34.93 after the No. 2 U.S. drugmaker reported quarterly profit and sales that beat estimates.
Chevron Corp, the second-largest U.S. oil company, said quarterly earning more than doubled, topping expectations, but The stock was off 0.4 percent at $108.58.
Shares of MF Global Holdings Ltd fell 6.3 percent to $1.34. Some customers are moving money from the futures brokerage, rivals, hedge fund officials and analysts said, though the extent of the outflows is unclear.
(Reporting by Angela Moon; editing by Kenneth Barry)