During the 1987 global stock-market crash, the U.S. trading day when the Dow Jones fell 22.6% was called Black Monday.
The date was October 19, 1987. The Dow Jones Industrial Average lost 508 points, then the largest one-day percentage decline in its history. Selling also spread rapidly across markets in Europe, Asia, Australia, and Canada, making the event a genuinely global crash.
The fall followed sharp market gains earlier in the decade and occurred amid concerns about interest rates, trade deficits, economic growth, and expensive share prices. Computerized trading and portfolio-insurance strategies may have intensified the selling, although historians and economists continue to debate the relative importance of each cause.
Black Monday is often confused with Black Thursday, October 24, 1929, an important day in the Wall Street Crash. The 1987 crash did not lead to a depression comparable to the 1930s, and U.S. markets recovered much of the decline comparatively quickly.