The 1987 crash regarded as the first major global financial crisis of the modern electronic trading era was Black Monday.
On October 19, 1987, stock markets around the world fell sharply. The Dow Jones Industrial Average suffered its largest one-day percentage decline, while major markets in Europe, Asia, and elsewhere also recorded severe losses. The speed and international reach of the fall made it a landmark event in modern market history.
Several factors were discussed afterward, including high valuations, rising interest rates, trade tensions, and computerized portfolio-insurance strategies. Program trading may have amplified selling, but historians and economists do not identify one universally accepted single cause.
Black Monday is sometimes confused with the 1929 day labels Black Thursday and Black Tuesday. Those names refer to different events. Black Monday in this context specifically means the worldwide market crash of October 19, 1987.