The S&P 500 traded below its lowest point for May at 1,311.80 as nervous investors honed in on key market levels to manage risk a day after stocks suffered their worst one-day fall in nearly a year.

The Dow Jones industrial average <.DJI> was down 74.09 points, or 0.60 percent, at 12,216.05. The Standard & Poor's 500 Index <.SPX> was down 5.75 points, or 0.44 percent, at 1,308.80. The Nasdaq Composite Index <.IXIC> was down 3.76 points, or 0.14 percent, at 2,765.43.

(Editing by Kenneth Barry)