A sudden, severe drop in the prices of most stocks traded on a stock market. During the stock market crash of 1929, the Dow Jones Industrial Average (DJIA) fell by 34 percent from its peak in September to the end of 1929. In the crash of 1987, the DJIA fell 31 percent from its peak in August to the end of 1987. A stock market crash may refer to a specific day when prices drop precipitously or to several days or months of substantial losses.