Which 1987 market crash began after Hong Kong’s Hang Seng Index plunged?

Black Monday was the 1987 market crash that followed a plunge in Hong Kong’s Hang Seng Index.

The Hong Kong market fell sharply on October 19, 1987, and trading was later suspended for several days. Selling then spread through international markets, reaching Europe and the United States. When New York trading ended that day, the Dow had suffered its largest one-day percentage decline.

The episode demonstrated how increasingly connected financial markets could transmit panic across time zones. Investors reacted to concerns about valuations, interest rates, currency arrangements, portfolio insurance, and computerized trading. No single explanation fully accounts for every market movement.

Black Monday is also used for the U.S. crash date of October 19, 1987. It should not be confused with Black Monday in 1929, which refers to October 28, or with later market declines that received the same nickname.