The 1987 global market crash was widely called Black Monday because its most dramatic day occurred on a Monday.
On 19 October 1987, stock markets around the world plunged. The Dow Jones Industrial Average fell 22.6% in a single session, its largest one-day percentage decline. Markets in Hong Kong, Europe, Australia, and elsewhere also recorded major losses, making the episode genuinely international.
The causes included high valuations, rising interest rates, trade tensions, and concerns about the U.S. dollar. Computerized portfolio insurance and other automated trading strategies may have amplified selling, although no single explanation accounts for every market movement.
Black Monday is distinct from Black Monday in 1929 and from the 2020 market decline. The shared nickname refers to separate crashes, so the year is important when identifying the event.