Black Monday was the most famous trading day of the 1987 global stock-market crash.
On October 19, 1987, stock markets around the world fell sharply. The Dow Jones Industrial Average dropped 22.6 percent in a single session, its largest one-day percentage decline at the time. Markets in Hong Kong, Europe, Australia, and other regions also experienced severe losses.
Explanations include overvalued shares, rising interest rates, trade tensions, portfolio insurance, and computerized trading strategies. No single cause fully explains the speed and international reach of the decline. Unlike the 1929 crash, the 1987 collapse was not followed by a decade-long depression.
Black Monday is sometimes confused with Black Monday on October 28, 1929, when the Dow fell substantially during the earlier Wall Street Crash. The 1987 event is specifically associated with October 19 and with the worldwide market break that year.