Dow Jones Industrial Average Plunges 350 Points As Greek Exit Fears Rise, S&P Slashes Greece's Credit Rating

U.S. stocks closed sharply lower Monday, with the Dow Jones Industrial Average plunging 300 points after Standard & Poor's slashed Greece's credit rating -- again -- amid the country's ongoing debt turmoil. The rating agency estimated there's a 50 percent chance of a Greek exit from eurozone, sending U.S. stocks spiraling 2 percent lower in the last hour of trading.