The biggest single-day session of the 1987 global stock-market crash was called Black Monday.
Black Monday occurred on October 19, 1987. The Dow Jones Industrial Average fell 508 points, or 22.6 percent, its largest one-day percentage decline in its history. Major markets in Europe, Asia, and elsewhere also suffered sharp losses, making the event genuinely global rather than limited to Wall Street.
Several factors were discussed afterward, including high share valuations, worries about interest rates and trade deficits, program trading, and portfolio-insurance strategies. No single explanation accounts for every market’s movements, but automated selling helped amplify the fall.
Black Monday is often confused with the 1929 market episodes also given weekday nicknames. The 1987 crash did not produce a depression on the scale of the 1930s, and many markets recovered relatively quickly compared with the prolonged decline after 1929.