OchAccording to preliminary calculations, the Dow Jones Industrial Average plunged 313 points, or 2.4%, to 12933, the S&P 500 slid 33.8 points, or 2.4%, to 1395 and the Nasdaq Composite fell 74.6 points, or 2.5%, to 2937. Volatility jumped 7.7% as tracked by the CBOE's VIX, regularly called Wall Street's fear gauge. Meanwhile, traders took shelter in the safety of U.S. Treasury bonds. The yield on the 10-year dropped 0.0113-percentage point to 1.638%.