Until recently, most investors assumed banks had put their troubles behind them, said Todd Salamone, director of research at Schaeffer's Investment Research. He pointed to JPMorgan Chase, the first large bank to release earnings. On Wednesday, the bank reported first-quarter results that beat forecasts, but chief executive officer Jamie Dimon warned that the bank could still take more losses from mortgages.
"That's one of the better banks," Salamone said, "so it makes you wonder what's going to happen."
Stock indexes were lower for most of the day after claims for unemployment benefits rose unexpectedly for the first time in three weeks.
Ford Motor Co. fell 1.1 percent. It said it was expanding its recall of its F-150 pickup truck because of a problem with air bags. Ford's F-Series truck is the best-selling vehicle in the United States.
Grocery chain Supervalu Inc., parent of Philadelphia-area Acme stores, said quarterly profits and sales had fallen compared with a year earlier, but analysts expected earnings to be worse. Supervalu rose nearly 17 percent.
Car-sharing company Zipcar Inc. shot up nearly 56 percent on its first day of trading.
Google Inc. fell 5 percent in after-market trading after it reported earnings that missed estimates.