On what date did the 1987 stock-market crash's most famous day, Black Monday, occur?

Black Monday, the most famous day of the 1987 stock-market crash, occurred on October 19, 1987.

On that Monday, stock markets around the world plunged. The Dow Jones Industrial Average fell 508 points, a decline of 22.6 percent, which was its largest one-day percentage loss at the time. Hong Kong, London, and other markets also experienced severe falls as financial markets became increasingly interconnected.

Researchers have linked the crash to overvaluation, investor anxiety, trade imbalances, rising interest rates, and computerized portfolio-insurance strategies. The exact cause remains debated, so it is misleading to attribute the event to a single factor. Unlike 1929, the 1987 crash did not lead to a similarly prolonged depression.