The S&P 500 and Nasdaq turned negative for the year on 2011's highest volume and the Dow suffered its worst performance since August on Wednesday as investors sold stocks on fears Japan's nuclear crisis could worsen.

The Dow Jones industrial average <.DJI> dropped 242.12 points, or 2.04 percent, to 11,613.30, according to the latest available figures. The Standard & Poor's 500 Index <.SPX> lost 24.99 points, or 1.95 percent, to 1,256.88. The Nasdaq Composite Index <.IXIC> fell 50.51 points, or 1.89 percent, to 2,616.82.

(Reporting by Chuck Mikolajczak; Editing by Kenneth Barry)