During the 1987 global stock-market crash, the Dow Jones Industrial Average suffered its largest one-day percentage drop on October 19, 1987.
That Monday became known as Black Monday. The Dow fell 508 points, or 22.6%, in a single trading session, a percentage decline that remains the largest in its history. Selling spread rapidly among major markets, including Hong Kong, London, and Australia, making the event an international crash rather than an isolated Wall Street decline.
Several pressures were present, including high interest rates, anxiety about the dollar, and program trading strategies that automatically sold futures and shares. The exact combination intensified the fall, but no single cause explains the entire episode.
Black Monday is sometimes confused with the 1929 crash dates. The 1987 event happened decades later, and its aftermath led regulators to develop circuit breakers designed to pause trading during extreme market moves.