The 1987 global stock-market crash, when the Dow Jones Industrial Average fell 22.6% in one day, was called Black Monday.
The fall occurred on October 19, 1987. It remains the largest one-day percentage decline in the Dow’s history. Markets elsewhere also plunged, showing how quickly electronic trading, international investment, and linked financial systems could transmit fear across borders.
Analysts debate the precise balance of causes, including overvalued shares, rising interest rates, trade tensions, portfolio insurance, and automated selling. Black Monday did not produce a depression comparable to the 1930s, partly because central banks supplied liquidity and the U.S. economy continued growing. The date is sometimes confused with Black Monday in 1929, but the 1987 event was a separate crash.