News that Spain's economy entered another recession renewed worries about the fragility of Europe's finances on Monday and nudged stocks lower.
The Dow Jones industrial average slipped 35 points to 13,192 shortly after noon Eastern.
The Spanish government said that country's economy shrank 0.3 percent in the first three months of the year, the second straight quarter of contraction.
Spain is the fourth-largest economy among the 17 countries that use the euro. The worry is that Europe's bailout funds won't be big enough to rescue Spain if it needs help.
A sharp drop in an index of Midwestern manufacturing and a slowdown in U.S. consumer spending last month added to worries that the U.S. economy is slowing down. Weaker earnings reports from health insurer Humana and the owner of the New York Stock Exchange, NYSE Euronext, also weighed on stock indexes.
The Standard & Poor's 500 index fell seven points to 1,396 and the Nasdaq composite fell 18 points to 3,051.
The losses were broad. Nine of the ten industry groups in the S&P 500 fell, led by materials. Only telecoms rose. The dollar and U.S. Treasury prices edged up slightly as investors parked money in low-risk assets.
European markets were mainly lower over growing concerns about Spain. Stocks were off 1.9 percent in Spain, 1.6 percent in France and 1.3 percent in Italy.
Ratings agency Standard & Poor's downgraded Spain's government debt to just three notches above junk Friday. On Monday S&P lowered its rating for 11 Spanish banks, which are loaded with bad debt from a collapsed housing market.
The stock market is coming off its best week in a month. The S&P 500 rise 1.5 percent last week and is still up 11 percent this year. If the S&P finishes lower Monday it will be the first loss after four days of gains.
Stocks to watch include Barnes & Noble, which is teaming up with Microsoft to create a unit to house the digital and college businesses of the bookseller and include a Nook application for Windows 8. The companies said they may separate those businesses entirely. That could mean a stock offering, sale, or some other kind of deal.
Barnes & Noble jumped 69 percent to $23.10. Microsoft was flat.
Health insurer Humana fell 8 percent to $80.73 after reporting a 21 percent drop in first-quarter profit as the company paid out more in claims, falling short of Wall Street expectations.
NYSE Euronext, owner of the New York Stock Exchange, fell 5 percent to $25.57 after reporting that its income plunged 44 percent in the first three months of the year. Trading business was weak and the company had to abandon a merger deal with the European exchange operator Deutsche Boerse.
Sunoco jumped 19 percent to $48.80, the most of any stock in the S&P 500, on news that the fuel-refining company agreed to be bought by Energy Transfer Partners, a natural gas pipeline partnership, for $5.3 billion.