October 19, 1987, is most commonly known as Black Monday.
On that Monday, the Dow Jones Industrial Average fell 508.32 points, or 22.6%, its largest one-day percentage decline. Stock markets in other countries also dropped sharply, making the event a global crash rather than a disturbance confined to the United States.
Several factors contributed, including worries about economic growth, rising interest rates, trade tensions, and an overvalued market. Computerized trading and portfolio-insurance strategies also accelerated selling once prices began to fall. The precise combination of causes remains a subject of financial-history research.
Black Monday is sometimes confused with the Black Monday of 1929, which occurred on October 28 that year. The 1987 crash was followed by rapid policy responses and did not develop into a depression like the 1929 collapse. The Dow recovered its pre-crash closing level by early 1989.