Black Monday was the 1987 stock-market crash in which the Dow Jones Industrial Average fell 22.6% in one session.
The collapse occurred on October 19, 1987. It was the largest one-day percentage decline in the Dow’s history, exceeding the percentage loss recorded on Black Tuesday in 1929. Markets also fell sharply in other countries, making the event a genuinely international crash.
Several forces contributed, including high valuations, rising interest rates, trade tensions, and computerized portfolio-insurance strategies that automatically sold futures as prices dropped. Those programmed sales may have accelerated the decline, although no single cause explains the event completely.
Unlike the 1929 crash, the 1987 collapse was not followed by a decade-long depression. The U.S. economy continued expanding, and the Dow recovered its pre-crash closing level by 1989. Regulators later introduced circuit breakers to pause trading during extreme market movements.