The 1987 global stock-market crash is commonly called Black Monday because its most dramatic trading day was Monday, October 19.
Markets fell sharply across the world after earlier declines in Asia and Europe. In the United States, the Dow Jones Industrial Average dropped 22.6%, while other major indexes also suffered exceptional losses. The synchronized movement showed how increasingly connected financial markets had become.
The crash was associated with worries about economic conditions, high valuations, trade imbalances, and automated selling strategies. Portfolio insurance programs were designed to limit losses, but their sell orders could add to downward momentum when prices declined quickly.
The nickname can cause confusion because “Black Monday” is also used for other market collapses, including events in 1929 and 2020. In financial history, the 1987 reference is usually identified by the year or by the Dow’s record percentage fall.