October 19, 1987, saw the Dow Jones Industrial Average lose 22.6%, its largest one-day percentage decline.
The date is widely known as Black Monday. Selling spread through international markets, and the decline was amplified by program trading, portfolio insurance strategies, and investor fear. Unlike the 1929 crash, the 1987 episode did not lead to a comparable decade-long economic depression in the United States.
The Federal Reserve responded by publicly affirming its readiness to provide liquidity to the financial system. Exchanges also later introduced circuit breakers designed to pause trading during extreme price movements.
The 22.6% figure refers to the Dow’s one-day percentage loss, not its biggest point loss. Point losses depend on the index’s level, so comparisons using points can produce a different historical ranking. The date itself remains the standard reference for the 1987 crash.