The 1987 event that caused a single-day 22.6 percent fall in the Dow Jones Industrial Average was Black Monday.
Black Monday occurred on October 19, 1987, when stock markets around the world plunged. The Dow’s 22.6 percent fall remains its largest one-day percentage decline. Analysts have identified several contributing factors, including rising interest rates, worries about trade deficits, portfolio insurance, computerized trading, and market contagion from other exchanges.
The crash did not develop into a depression comparable to the 1930s. The U.S. Federal Reserve, led by Alan Greenspan, issued a statement supporting market liquidity, and financial institutions continued operating. Regulators later introduced circuit breakers, which can temporarily halt trading after unusually large price movements. Black Monday is distinct from the 1929 Black Tuesday and from the 2010 Flash Crash.