During the 1987 stock-market crash, 19 October was nicknamed Black Monday.
On that Monday, the Dow Jones Industrial Average lost 508 points, or 22.6%, its largest one-day percentage decline in the index’s history. Selling spread rapidly across international markets, including Hong Kong, London, and Australia, making the event a genuinely global crash rather than an isolated U.S. decline.
Several factors were associated with the collapse, including high share valuations, anxiety about interest rates and trade deficits, and computerized portfolio-insurance strategies that generated more sell orders as prices fell. Researchers continue to debate how much each factor contributed, but the speed and scale of automated trading were especially important in discussions after the crash.
Black Monday is sometimes confused with other “Black” market dates, including Black Thursday in 1929 and Black Monday in 1929. The 1987 event is distinct because the Dow’s percentage loss exceeded the worst single day of the 1929 crash.