TOKYO, Japan - August 4, 2011 - Asian stock markets tumbled Friday amid fears the U.S. is mired in Depression and Europe’s debt crisis is worsening. The sell-off follows the biggest one-day points decline on Wall Street since the 2008 financial crisis.

Oil extended sharp losses to fall below $86 a barrel amid expectations a slowing global economy will undermine demand for crude.

Japan’s Nikkei 225 stock average slid 3.7% to 9,303.95 and Hong Kong’s Hang Seng dived 4.8% to 20,844.59. China’s Shanghai Composite Index lost 1.9% to 2,633.52.

“Losses today have been indiscriminate,” said IG Markets strategist Ben Potter in a report. “The big question on everyone’s mind is what will happen across European and U.S. markets tonight and will there be any form of emergency policy response?”

The Dow closed Thursday down 512.76 points, at 11,383.68. It was the steepest point decline since December 1, 2008.

Thursday’s decline was the ninth-worst by points for the Dow. In percentage terms, the decline of 4.3% does not rank among the worst. On Black Monday in 1987, for example, the Dow fell 22%.