The worldwide stock-market crash of October 19, 1987, when the Dow Jones Industrial Average fell 22.6%, is called Black Monday.
The Dow Jones Industrial Average dropped 508 points that day, its largest one-day percentage decline in history. Selling spread rapidly from Hong Kong and Australia to Europe and the United States, making the episode an international crash rather than a purely American event.
Several factors contributed, including computerized trading, portfolio insurance, high valuations, and concerns about interest rates and the dollar. The crash is often confused with the 1929 Wall Street Crash, but Black Monday occurred nearly six decades later. Regulators subsequently introduced circuit breakers to slow extreme market declines.