The 1987 worldwide stock-market crash was known as Black Monday.
Black Monday began on October 19, 1987, when major markets fell sharply. The Dow Jones Industrial Average dropped 22.6 percent in a single session, its largest one-day percentage loss in its history. Hong Kong’s market fell first in the sequence, and selling then spread through Europe and North America.
Possible contributing factors included high valuations, rising interest rates, trade tensions, and the growing use of computerized portfolio-insurance strategies. Those automated strategies could increase selling as prices declined, although no single explanation accounts for every market’s behavior. Trading systems also struggled with the unprecedented volume.
Black Monday is often confused with Black Tuesday, October 29, 1929, during the Wall Street Crash. Despite the shared color-based nickname, the two crashes occurred nearly six decades apart and in different technological environments. Authorities responded to 1987 by improving market safeguards, including circuit breakers and coordinated international supervision.