The Dow Jones Industrial Average lost 22.6% on October 19, 1987, the U.S. market crash known as Black Monday. It was the largest one-day percentage decline in the index’s history, exceeding the losses recorded during major earlier crashes.
Selling spread rapidly through international markets. Hong Kong fell first in the global sequence, followed by markets in Europe and North America. In the United States, program trading, portfolio insurance, investor fear, and market-structure pressures contributed to the speed of the decline.
The percentage loss is calculated from the Dow’s closing level on the previous trading day to its close on October 19. The index fell 508 points, a large point move that was especially striking because the Dow stood at a much higher level than in earlier decades.
The crash did not lead to a depression comparable to the 1930s. The Federal Reserve supplied liquidity, and financial regulators later introduced circuit breakers designed to pause trading during extreme market moves.