Stocks took a sharp nosedive in another choppy day Monday to finish at session lows as investors fled from risky assets following S&P's downgrade of U.S.'s credit rating last week in addition to ongoing economic jitters.

The Dow Jones Industrial Average plunged 634.76 points, or 5.55 percent, to finish at 10,809.85, well-below the psychologically-significant 11,000 mark. The move marks the blue-chip index's biggest point and percent drop since Dec. 1, 2008.  [cnbc]