Black Monday was the trading day in 1987 when the Dow Jones Industrial Average fell 22.6% in one session.
The crash occurred on October 19, 1987, and it affected stock markets around the world. Hong Kong, London, Sydney, and other markets also suffered severe losses. The Dow’s percentage decline remains the largest single-day fall in its history.
Several forces contributed, including high valuations, rising interest rates, investor anxiety, and automated portfolio-insurance strategies that encouraged rapid selling. Program trading became a major focus of later investigations, although no single cause explains the entire crash.
Black Monday is often confused with the 1929 crash days known as Black Thursday and Black Tuesday. It also differs from “Black Monday” in 2020, when markets plunged during the early COVID-19 shock.