The 1987 event that caused global share markets to plunge, beginning with Hong Kong on October 19, was Black Monday.
On October 19, 1987, stock markets around the world fell sharply. Hong Kong experienced the earliest major collapse that day, and selling later spread through Europe and North America. The Dow Jones Industrial Average dropped 22.6 percent, its largest one-day percentage decline.
Several factors contributed, including high valuations, concerns about interest rates and trade deficits, and computerized portfolio-insurance strategies that encouraged additional selling. The precise balance among these causes remains debated, but the international speed of the fall made the episode historically distinctive.
This Black Monday is different from Black Monday dates associated with 1929 and 2020. The 1987 crash also differed from 1929 because it was not followed by a depression of comparable scale. Market regulators later introduced circuit breakers and other safeguards.