The worldwide stock-market plunge that began on October 19, 1987, was nicknamed Black Monday.
Black Monday began in Hong Kong before spreading westward through Europe and North America. In the United States, the Dow Jones Industrial Average lost 22.6% on October 19, its largest one-day percentage decline. Australia, Canada, Hong Kong, and the United Kingdom also recorded severe falls during the episode.
The crash followed a period of rising markets and growing concern about valuations, interest rates, trade tensions, and the U.S. dollar. Automated trading and portfolio-insurance strategies were widely examined because they could reinforce selling once prices started to fall.
The name can cause confusion because Black Tuesday refers to October 29, 1929, while Black Monday is also used for other market declines. In the 1987 context, the nickname specifically identifies the synchronized global crash centered on October 19. Coordinated central-bank action and market reforms helped prevent a longer systemic collapse.