Black Monday, the day the Dow Jones Industrial Average fell 22.6% in 1987, occurred on October 19, 1987.
The worldwide market crash began in Hong Kong and spread through Europe before reaching the United States. The Dow Jones Industrial Average lost 508 points, or 22.6%, in one session. That percentage decline remains the largest single-day percentage fall in the index’s history.
Several forces contributed, including stretched valuations, rising interest rates, trade tensions, and computerized portfolio-insurance strategies. Selling fed on itself as automated and institutional trading increased the speed of price declines. The fall was not confined to the United States; markets around the world also dropped sharply.
The crash prompted regulators and exchanges to review market structure. Circuit breakers were later introduced or expanded to pause trading during exceptionally rapid declines. Despite the dramatic fall, the United States did not enter a depression comparable to the 1930s, and the economy continued to grow afterward.