Which 1987 crash saw the Dow Jones lose 22.6% in one trading day?

Black Monday was the 1987 stock-market crash in which the Dow Jones Industrial Average lost 22.6% in one trading day.

The fall happened on October 19, 1987, and remains the largest one-day percentage decline in Dow history. Markets around the world also plunged, including major exchanges in Hong Kong, London, and Australia. Unlike the 1929 crash, the 1987 decline was not followed by a decade-long depression in the United States.

Several explanations have been studied, including overvalued shares, rising interest rates, trade tensions, and computerized portfolio-insurance selling. Program trading could intensify downward momentum by automatically selling as prices fell. The phrase “Black Monday” is sometimes used for other market collapses, but in stock-market history it most commonly refers to October 19, 1987.