The U.S. market crash that began on October 19, 1987, was called Black Monday.
The Dow Jones Industrial Average fell 22.6 percent that day, its largest one-day percentage decline in its history. Selling also spread to other major markets, making the event a global stock-market crash rather than an isolated American drop.
Several forces contributed, including high valuations, concerns about interest rates and trade deficits, portfolio insurance strategies, and increasingly rapid computer-assisted trading. The precise balance among these factors remains debated, but automated selling amplified the downward move.
Unlike the 1929 crash, Black Monday did not lead to a decade-long depression. Central banks supplied reassurance and liquidity, and regulators later introduced circuit breakers designed to pause trading during extreme declines. The Dow recovered much of its loss over the following months.