The 1987 stock-market crash is known as Black Monday. On October 19, 1987, the Dow Jones Industrial Average fell 508 points, or 22.6%, its largest one-day percentage decline. The drop followed sharp losses in markets across Asia and Europe, making it an international event rather than an isolated Wall Street shock.
Several forces were involved. Investors worried about interest rates, trade tensions, and an overvalued market, while computerized portfolio-insurance strategies automatically sold futures as prices declined. Those sales added pressure to an already nervous market. The crash was severe, but it did not produce the prolonged economic collapse associated with 1929.
The Federal Reserve, led by Alan Greenspan, issued a statement supporting the financial system and supplied liquidity. Exchanges later introduced circuit breakers to pause trading during unusually rapid declines. Black Monday is sometimes confused with the 1929 Black Tuesday, but the two crashes occurred nearly six decades apart.