What nickname was given to the 1987 crash’s record one-day fall in U.S. stocks?

The record one-day fall in U.S. stocks on October 19, 1987, was nicknamed Black Monday.

The Dow Jones Industrial Average lost 22.6% in a single trading session, a percentage decline larger than any other day in the index’s history. The S&P 500 and Nasdaq Composite also suffered major losses, while markets in Europe, Asia, and Australia were affected by the same worldwide wave of selling.

The nickname can cause confusion because “Black Monday” is also used for other market declines, including October 28, 1929, and October 27, 1997. In standard financial-history usage, however, Black Monday most often means October 19, 1987. The crash prompted investigations into trading mechanisms and helped produce modern market-wide trading halts, commonly called circuit breakers.