The Dow Jones industrial average fell as much as 527 points, the second consecutive rout since the Federal Reserve announced a change in strategy for fighting the economic slowdown.
At the close of trading, the Dow was down 391.01 points, or 3.5 percent, at 10,733.83. The Standard & Poor's 500 index fell 37.18, or 3.2 percent, to 1,129.58. The Nasdaq composite fell 82.52, or 3.3 percent, to 2,455.67.
Nineteen stocks fell for every one that rose. Trading volume was high on the New York Stock Exchange, at 6.9 billion.
Oil and metals prices, which rely on economic demand, sank. Traders sought the safety of Treasury bonds.