The sudden U.S. stock-market collapse on October 19, 1987, was called Black Monday.
The Dow Jones Industrial Average fell 508 points, or 22.6%, in a single session, the largest one-day percentage decline in its history. Selling spread rapidly through international markets, and computerized portfolio-insurance strategies amplified the downward pressure. The crash followed a sharp rise in prices earlier in the decade and growing concern about interest rates and trade deficits.
Unlike the 1929 crash, Black Monday did not lead to a decade-long depression. Federal Reserve Chair Alan Greenspan announced that the central bank was ready to provide liquidity, helping calm banks and markets. Trading rules were later changed, including circuit breakers designed to pause trading during extreme declines. The date is distinct from Black Monday in October 1929, so the year matters.