The Dow Jones Industrial Average lost 22.6% on October 19, 1987, the largest one-day percentage decline in its history.
The date became known as Black Monday. Stock markets around the world also fell, making the event a global crash rather than a purely American sell-off. In the United States, the Dow dropped 508 points, a dramatic figure for the size of the index at the time.
Several factors were discussed afterward, including high valuations, economic concerns, portfolio insurance, and computerized trading. No single cause fully explains the speed and scale of the decline.
Unlike the 1929 crash, Black Monday did not lead to a prolonged depression. The U.S. economy continued growing, and market regulators introduced changes such as circuit breakers to pause trading during extreme moves.