The 19 October 1987 stock-market crash day that sent the Dow down 22.6% was Black Monday.
Black Monday was the largest one-day percentage decline in the Dow Jones Industrial Average. The index dropped 508 points, a fall of 22.6%, as markets around the world also suffered severe losses. Hong Kong was among the first major markets to plunge, and the selling spread westward through Europe and North America.
Several factors were associated with the crash, including overvalued shares, rising interest rates, trade tensions, and computerized portfolio-insurance strategies. These automated systems could intensify selling when prices declined.
The crash did not produce a depression like the 1929 collapse. The U.S. Federal Reserve, led by Alan Greenspan, supplied liquidity and reassured financial institutions. Markets eventually recovered, although the event changed trading safeguards and risk management.