(Bloomberg)—The sell-off in global stocks deepened, leaving U.S. shares mired in the steepest two-day slide since February and European equities at a two-year low as concern mounted that the rate of global economic growth has peaked. Oil slid as OPEC ministers met in Vienna. The S&P 500 has tumbled more than 5 percent in two sessions, while the Dow Jones Industrial Average shed almost 1,500 points on bets that the trade truce between China and the U.S.