The Dow Jones Industrial Average closed down 204.91 points, or 1.29 percent, at 15,666.44, with Merck plunging 5.2 percent as the greatest laggard and Apple and Walt Disney the only advancers. The Dow transports also reversed intraday gains to close down 1.7 percent, solidly in correction territory. The S&P 500 closed down 25.6 points, or 1.35 percent, at 1,867.61, with utilities plunging more than 3 percent to lead all 10 sectors lower. The Nasdaq closed down 19.76 points. or 0.44 percent, at 4,506.49.