In what month did the 1987 stock market crash occur?

The 1987 stock market crash occurred in October.

Its defining day was Monday, October 19, 1987, which became known as Black Monday. The Dow Jones Industrial Average plunged 508 points, a one-day loss of 22.6 percent—the largest percentage decline in the index’s history.

The fall was global rather than limited to the United States. Asian and European markets had already suffered major declines, and selling pressure spread across futures, options, and stock markets. Computerized trading strategies, portfolio insurance, high valuations, trade and budget concerns, and rising interest rates were among the factors examined afterward.

The crash did not produce a repeat of the Great Depression. The Federal Reserve supplied liquidity, and the Dow began recovering in November. Regulators and exchanges later introduced or strengthened trading curbs designed to slow disorderly selling during extreme market moves.