U.S. stocks fell on Tuesday after a disappointing revenue miss from Alcoa to start off the earnings season and a sell-off in commodities, coupled with Japan's upgrade of the severity of its nuclear crisis.

Shares in Alcoa Inc slipped 5 percent to $16.88 shortly after the open. The company reported revenue that missed forecasts after the closing bell on Monday.

Japan raised the severity of the Fukushima nuclear power plant accident to the highest level on the International Nuclear and Radiological Event Scale, putting it on par with the Chernobyl 1986 disaster.

Mining stocks fell as metals prices dipped on worries Japan's massive earthquake and a nuclear crisis would weaken recovery prospects in the world's third-largest economy.

Selling in key commodities were also triggered after Goldman Sachs warned its clients to lock in trading profits before oil and other markets reverse. U.S. traded shares of Rio Tinto fell 2 percent to $72.36.

The market is increasingly becoming concerned about the situation in Japan and that high oil prices and high commodity prices will eventually hurt economic growth, said Mark Bronzo, money manager at Security Global Investors in Irvington, New York.

The Dow Jones industrial average <.DJI> was down 64.56 points, or 0.52 percent, at 12,316.55. The Standard & Poor's 500 Index <.SPX> was down 6.89 points, or 0.52 percent, at 1,317.57. The Nasdaq Composite Index <.IXIC> was down 14.67 points, or 0.53 percent, at 2,756.84.

(Reporting by Angela Moon, Editing by Chizu Nomiyama)