During Black Monday in 1987, the Dow Jones Industrial Average lost 22.6% in one trading session.
The collapse occurred on Monday, October 19, 1987, after sharp declines had already affected markets in Asia and Europe. The Dow fell 508 points, from 2,246.74 to 1,738.74, producing the largest one-day percentage decline in its history.
Several factors were associated with the fall, including overvalued shares, rising interest rates, trade tensions, and computerized portfolio-insurance strategies. No single explanation fully accounts for the speed and scale of the selling.
Black Monday is often confused with the 1929 crash or with later market declines. Unlike 1929, the 1987 plunge did not lead to a comparable decade-long economic depression, and the Dow eventually recovered its pre-crash level.