Stocks plunged on Monday, with the S&P down more than 6 percent for its largest drop in nearly three years on rising fears of a recession exacerbated by the United States' loss of its triple-A credit rating.

Panicked selling on heavy volume resulted in the S&P's worst day since December 2008 with every stock in the benchmark index's components ending in negative territory.

The Dow Jones industrial average dropped 634.76 points, or 5.55 percent, to end unofficially at 10,809.85. The Standard & Poor's 500 Index sank 79.92 points, or 6.66 percent, to finish unofficially at 1,119.46. The Nasdaq Composite Index lost 174.72 points, or 6.90 percent, to close unofficially at 2,357.69.

(Reporting by Chuck Mikolajczak; Editing by Jan Paschal)