The U.S. stock-market crash that began on October 19, 1987, was known as Black Monday.
The Dow Jones Industrial Average fell 508 points that day, a decline of 22.6%. Markets in Hong Kong, Europe, and other regions had already experienced substantial losses, making the event a global equity-market shock rather than an isolated U.S. episode.
Explanations for the crash include elevated valuations, investor anxiety about interest rates and trade deficits, portfolio insurance, and computerized selling. No single cause fully accounts for the speed and scale of the decline.
Regulators responded by developing circuit breakers and other trading safeguards. Despite the dramatic fall, the U.S. economy did not enter a depression, and the Dow eventually recovered its pre-crash closing level.