In midmorning trading, the Dow Jones industrial average fell 443.08, or 4.29 percent, to 9,882.30, dropping below 10,000 for the first time since Oct. 29, 2004. At one point, the Dow was down nearly 600.
Broader indexes also tumbled. The Standard & Poor's 500 index shed 53.12, or 4.83 percent, to 1,046.11; and the Nasdaq composite index fell 101.07, or 5.19 percent, to 1,846.32. The Russell 2000 index of smaller companies dropped 29.31, or 4.73 percent, to 590.09.
The MSCI World Index lost 2.7 percent to 1,107.98 at 12:09 p.m. in London as all 10 industry groups decreased. National markets in China, Germany, France, Japan, South Korea and the U.K. fell more than 4 percent.
National benchmark indexes sank in all 18 western European markets. France's CAC 40 slumped 8.13 percent, and Germany's DAX fell 7.39 percent.
U.K. stocks plummeted, heading for their lowest close in almost four years, led by banks and mining companies on concern the credit-crisis is deepening and as metals prices plunged. FTSE 100 decreased 5.1 percent to 4,677.24.
Canadian stocks had their biggest drop since the ``Black Monday'' crash of October 1987, led by commodity producers, on concern their profits will be hurt by a global recession. The main index fell more than 1,000 points. The Standard & Poor's/TSX Composite Index fell 1,086.94, or 10 percent, to 9,716.94 at 10:48 a.m. in Toronto for its biggest drop since October 1987.
Brazil's Bovespa index tumbled 10 percent. Trading was halted 20 minutes after the open as the Bovespa tumbled 4,491.84 points to 40,025.48, the lowest since November 2006. Russia's Micex Index plunged 18 percent before trading was halted for a second time today.
Australian stocks fell, dragging the benchmark index to the lowest in almost three years, on concern the credit crisis will slow global growth and curb demand for raw materials as it spreads to Europe. The S&P/ASX 200 Index fell 3.3 percent to 4,540.40 at the close in Sydney, the lowest since Nov. 9, 2005.
Japan's stocks dropped, driving the Topix index below 1,000 points for the first time since December 2003, after the global credit crisis deepened in Europe and the yen jumped, cutting the value of overseas sales. The Topix fell 48.92, or 4.7 percent, to close at 999.05 in Tokyo. Only 93 of 1,714 members included in the index rose. The Nikkei 225 Stock Average declined 465.05, or 4.3 percent, to 10,473.09.
China's stocks fell, giving the benchmark index its biggest loss in seven weeks, as commodity prices slumped amid concerns the global credit crisis is widening. China's CSI 300 Index fell 5.1 percent, as trading resumed after a one-week holiday.
India's stock benchmark slumped to its lowest in more than two years as the credit crisis deepened in Europe reinforcing concern the global economy will slow. The Bombay Stock Exchange's Sensitive Index, or Sensex, tumbled 724.62 points, or 5.8 percent, to 11,801.70, the lowest since Sept. 12, 2006.
The MSCI Emerging Markets Index headed for its steepest drop in at least two decades. BHP Billiton Ltd. slid 7.8 percent and UBS AG lost 10 percent as commodities producers and banks dropped the most in the MSCI World Index.