The 1987 market crash that began in Hong Kong on 19 October and spread worldwide was called Black Monday.
Hong Kong’s Hang Seng Index fell 11.1% on 19 October 1987, its first trading day after major losses in the United States. The shock moved westward through international markets. By the time New York opened, investors were facing intense selling pressure, and the Dow Jones Industrial Average plunged 22.6%.
The name Black Monday is used for the global crash, although different countries experienced their largest losses on different calendar dates because of time-zone differences. In some markets, the most severe decline therefore occurred on 20 October.
The crash exposed weaknesses in trading systems and risk models. Afterward, exchanges developed circuit breakers and other procedures intended to pause trading when prices moved too quickly. Black Monday is distinct from Black Monday in 1929, which refers to the 28 October collapse during the earlier Wall Street Crash.