The global stock-market crash on 19 October 1987 was called Black Monday.
The Dow Jones Industrial Average fell 508 points that day, a decline of 22.6 percent. It remains the largest one-day percentage drop in the Dow’s history. Markets in other countries also fell sharply, making the event an international crash rather than an isolated Wall Street decline.
Several factors contributed, including high share valuations, rising interest rates, trade tensions, and the growing use of computerized trading strategies. Portfolio insurance programs amplified selling when prices began to drop.
Black Monday is sometimes confused with the 1929 crash days called Black Thursday and Black Tuesday. Regulators later introduced circuit breakers designed to pause trading during exceptionally rapid declines.