What was the name of the 1987 stock-market crash's famous Monday trading day?

The famous Monday trading day of the 1987 stock-market crash was called Black Monday.

Black Monday occurred on October 19, 1987, when stock markets around the world plunged. The Dow Jones Industrial Average fell 508 points, or 22.6%, making it the largest one-day percentage decline in the index's history. Hong Kong and other markets had already experienced major falls before the New York session.

Analysts identify several contributing pressures rather than one universally accepted cause. Valuations were high, interest rates had risen, trade tensions worried investors, and computerized trading strategies accelerated selling. Portfolio insurance was designed to limit losses but could add more sell orders as prices declined.

Black Monday is often confused with Black Tuesday, the climactic day of the 1929 Wall Street Crash. The names refer to different crashes separated by nearly six decades. Despite the severity of the 1987 fall, monetary intervention and economic resilience helped prevent a repeat of the Great Depression.