October 19, 1987, is commonly known as Black Monday, when global stock markets suffered their sharpest one-day falls of the modern era.
On that Monday, the Dow Jones Industrial Average fell 508 points, or 22.6%, the largest one-day percentage decline in its history. Markets in other countries also dropped dramatically, making the event an international crash rather than an isolated U.S. sell-off. The Hang Seng Index fell 46%, while the FTSE 100 later lost 26.4% over the crash period.
Several forces contributed, including rising interest rates, concerns about the U.S. trade deficit, rapidly expanding computer-assisted trading, and investor behavior that reinforced the decline. No single event has been established as the sole cause.
The name can be confused with other market dates. Black Thursday refers to October 24, 1929, while Black Tuesday refers to October 29, 1929, during the earlier Wall Street Crash. October 19, 1987, is specifically associated with Black Monday.