The global stock-market crash known as Black Monday occurred in 1987.
The defining session was October 19, 1987, when the Dow Jones Industrial Average fell 22.6%, its largest one-day percentage decline. The selling was not limited to New York: major markets in Hong Kong, London, Australia, Canada, and elsewhere also suffered steep losses around the same period.
Before the crash, markets had risen strongly and valuations were high. Investors were also concerned about interest rates, the U.S. trade deficit, and a falling dollar. Computerized portfolio-insurance strategies added mechanical selling pressure as prices declined, although historians and regulators continue to debate the exact weight of each cause.
The crash led to important changes in market structure. Regulators created circuit breakers designed to pause trading during exceptionally rapid declines, and exchanges improved coordination. Unlike the 1929 crash, the 1987 event did not produce a comparable long economic depression, and many markets recovered relatively quickly.