American Express Co. had the largest move of the 30 stocks that make up the Dow Jones industrial average. The card issuer fell 3.4 percent to $42.50 after Stifel Nicolaus downgraded the company. New rules proposed by the Federal Reserve could limit fees the company charges merchants.
Aloca Inc. led the Dow index with a 1.4 percent gain to $14.77.
The Dow fell 13.78, or 0.1 percent, to 11,478.13. The Standard and Poor's 500-stock index rose 3.17, or 0.3 percent, to 1,247.08. The Nasdaq composite index gained 6.59, or 0.3 percent, to finish at 2,649.56.
The yield on the 10-year Treasury bond rose slightly to 3.34 from 3.33 percent late Friday.
Stocks have been rising strongly in December. The Dow has gained 4.3 percent so far this month and the S&P has hit seven new annual highs since Dec. 8.
Investors have been encouraged by improving economic data on retail sales, consumer confidence and factory production, as well as policy changes that will benefit stockholders. President Barack Obama signed a bill last week that will keep Bush-era income tax cuts in place for another two years. The law will also extend favorable tax rates on capital gains and dividends.
"The markets ... made quite a run," said Stephen Carl, principal and head of equity trading at The Williams Capital Group. But the tax cuts "can only go so far," Carl said, and are unlikely to continue sending stocks higher.
In corporate news, Boeing Inc. fell 2.7 percent to $63.27 even as the company said it was increasing the production rate for its 777 aircraft again in response to strong demand. Last week, the aerospace giant said that customers canceled orders for three 777s and one of its 787s.
Medtronic Inc. rose 0.6 percent to $37.62 after the world's largest medical device manufacturer said its chairman and CEO will step down in April after leading the company for three years.
Later in the week, investors will get reports from shoe maker Nike Inc., used car dealership chain CarMax Inc. and pharmacy operator Walgreen Co.
Markets will be closed on Friday in observance of Christmas.
The dollar gained 0.3 percent against an index of six heavily-traded currencies. Commodity prices rose 1.1 percent.
Rising and falling shares were even on the New York Stock Exchange. Trading volume came to 830 million shares.