The Dow plunged nearly 513 points Thursday, its biggest point decline since Oct. 22, 2008. Only three of the 500 stocks in the Standard & Poor's 500 index had gains. Oil fell by 6 percent. The yield on the two-year Treasury note hit a record low as investors sought out relatively stable investments.
All three major stock indexes are down 10 percent or more from their previous highs, a drop-off that is considered to be a market correction. A drop of 20 percent or more signifies the start of a bear market, an extended period of stock declines.
Investors are increasingly concerned about the possibility of another recession in the U.S. and a debt crisis in Europe.