U.S. banks were the S&P 500's worst performing sector. Investors feared that weak euro zone growth would hamper countries dealing with heavy debt loads and the banks exposed to those debts.
"We're very concerned around the markedly deteriorating credit fundamentals in Europe," said Steven Baffico, chief executive officer at Four Wood Capital Partners in New York.
Data showing weakness in the euro zone services and manufacturing sectors overshadowed the day-old deal to bail out Greece.
After touching a near 7-month high on Tuesday, the KBW bank index .BKX fell 2 percent. A key European bank index .SX7P declined 2.5 percent.
The S&P 500 index failed again to hold above 1,360, the high reached last May and a key resistance point that could spark further gains if broken. The benchmark index is up about 8 percent for the year and gained more than 20 percent from its October lows.
The Dow Jones industrial average finance/markets/index?symbol=us%21dji">.DJI/a> lost 27.02 points, or 0.21 percent, to 12,938.67. The S&P 500 Index .SPX dropped 4.55 points, or 0.33 percent, to 1,357.66. The Nasdaq Composite .IXIC fell 15.40 points, or 0.52 percent, to 2,933.17.