October 19, 1987, is known as Black Monday, the day global stock markets suffered their biggest one-day percentage collapse. The Dow Jones Industrial Average fell 22.6%, its largest single-day percentage decline.
Selling spread rapidly across international markets. Hong Kong fell first among major markets, and losses then moved through Europe and North America. The crash was intensified by computerized trading strategies, portfolio insurance, high valuations, and concerns about economic conditions and currency movements.
Black Monday is often confused with the Black Monday associated with the 1929 crash, but the 1987 event has its own date and scale. Unlike the 1929 collapse, the 1987 crash was followed by a relatively short recession, and the Dow eventually recovered. Regulators later introduced circuit breakers and other safeguards intended to slow panic selling.