Stocks fell 2 percent on Wednesday and the S&P turned negative for the year as worries about Japan's nuclear crisis escalated.
The Nasdaq was also negative for the year, while the Dow briefly dropped under its 2010 closing level. The CBOE Volatility index <.VIX> surged 28 percent to 31.07.
The Dow Jones industrial average <.DJI> tumbled 284.65 points, or 2.40 percent, at 11,570.77. The Standard & Poor's 500 Index <.SPX> slid 31.38 points, or 2.45 percent, at 1,250.49. The Nasdaq Composite Index <.IXIC> sank 61.46 points, or 2.30 percent, at 2,605.87.
(Reporting by Ryan Vlastelica)