October 19, 1987, the biggest one-day percentage fall in many major stock markets, became known as Black Monday.
The Dow Jones Industrial Average plunged 22.6% that day, its largest one-day percentage decline. Stock markets in Hong Kong, Australia, the United Kingdom, and other countries also suffered major losses, making the event international rather than solely American.
Researchers have linked the crash to several interacting factors, including high valuations, rising interest rates, trade tensions, and computerized portfolio-insurance strategies. These automated sell programs could intensify a decline as prices fell, although no single explanation accounts for every market.
Black Monday is often confused with the 1929 Black Monday and Black Tuesday episodes. The name is also used for other market declines, so the year matters. Despite the dramatic fall, the United States avoided a depression, and the Dow eventually recovered its pre-crash level.