High volatility marked the week, with the S&P 500 falling 2.3 percent on Monday in its worst day since November 7, which fueled talk that the market's long-awaited pullback had arrived.
Friday's trading volume, at 6.4 billion, was the lowest of the week, but in line with the average for the year. Much of Boston, a major U.S. financial center and home to a number of the country's biggest mutual fund companies, was under virtual lockdown as police killed one suspect in the Boston Marathon bombing in a shootout and mounted house-to-house searches for a second man.