Dow plunges 634 points; Nasdaq, S&P fall almost 7%

Final numbers: Dow closed at 10,809.85, a loss of 634.76 points, or 5.55%.

The S$P 500 ended at 1,119.46, a drop of 79.92 points, or 6.66%. (Uh-oh, the "devil's number" ...)

The Nasdaq finished at 2,357.89, a daily loss of 174.72 points, or 6.9%.