Wall Street plummets as fear jumps on historic downgrade

(Reuters) - U.S. stocks plunged on Monday in the heaviest volume since last year's "flash crash," taking the S&P 500 down more than 6 percent on growing fears of a recession, - Wall Street plummets as fear jumps on historic downgrade -- US Stocks Plunge In Sixth Biggest DJIA Decline In History; DJIA Falls 634.76 WSJ