Black Monday, the most famous day of the 1987 global stock-market crash, occurred on October 19, 1987.
The Dow Jones Industrial Average fell 508 points, or about 22.6%, that day. It was the largest one-day percentage decline in the Dow’s history, and major markets around the world also suffered steep losses. The crash followed several days of weakness rather than appearing entirely without warning.
Analysts have associated the collapse with high valuations, rising interest rates, investor concerns about trade deficits, and computerized trading strategies such as portfolio insurance. No single explanation accounts for every market’s movements. Black Monday is sometimes confused with the 1929 Wall Street Crash, but the dates and financial conditions were different. Regulators later introduced circuit breakers designed to pause trading during exceptionally rapid declines.