The trading day on 19 October 1987 when the Dow Jones Industrial Average lost 22.6% was Black Monday.
The fall was the largest one-day percentage decline in the Dow’s history. The index dropped 508 points, from 2,246.74 to 1,738.74. Selling spread rapidly across major markets, including Hong Kong, London, and Australia, making the event an international crash rather than an isolated U.S. shock.
Several factors were associated with the collapse, including high valuations, worries about interest rates and trade deficits, and computerized portfolio-insurance strategies that automatically sold as prices fell. Economists still debate how much each factor contributed.
Black Monday is often confused with the 1929 U.S. crash days called Black Thursday and Black Tuesday. The 1987 episode did not produce a Great Depression, partly because central banks supplied liquidity and markets later recovered.