What was the nickname of the 1987 stock-market crash’s worst day?

The nickname of the 1987 stock-market crash’s worst day was Black Monday.

Black Monday occurred on October 19, 1987, when stock markets around the world plunged. The Dow Jones Industrial Average lost 22.6 percent in a single session, its largest one-day percentage decline in its history. Markets in Hong Kong, the United Kingdom, Australia, Canada, and other countries also suffered severe losses.

Analysts have linked the crash to several factors rather than one universally accepted cause. These included rising interest rates, an overvalued market, trade concerns, and computerized portfolio-insurance strategies that accelerated selling.

Black Monday is sometimes confused with the 1929 crash days called Black Thursday and Black Tuesday. Despite its severity, the 1987 crash did not lead to an economic depression comparable to the Great Depression.