US stocks tumbled Thursday ahead of a much-anticipated speech by Federal Reserve Chairman Ben Bernanke on Friday and as European woes renewed global growth worries. After hovering near breakeven for the past three days, the main indices remained stuck in red from the opening bell. The Dow Jones Industrial Average shed 105.53 points (0.81 percent) at 13,001.95 in closing trade. The S&P 500-stock index slid 10.80 (0.77 percent) to 1,399.69, while the tech-heavy Nasdaq lost 32.48 (1.05 percent) at 3,048.71. Friday\'s eagerly anticipated speech by Bernanke in Jackson Hole, Wyoming was \"fostering caution on the Street,\" Charles Schwab analysts said. Stocks were also under pressure \"as global economic growth concerns are flaring up,\" they added.