The 1987 worldwide stock-market crash was known as Black Monday.
The name refers to October 19, 1987, when stock markets plunged across the world after an initial sharp fall in Hong Kong. The selling then moved through Europe before reaching the United States, where the Dow Jones Industrial Average suffered its record percentage decline.
The crash was not confined to one country or exchange. Australia, Canada, Hong Kong, the United Kingdom, and the United States all experienced severe losses, although their market calendars meant the dates were not identical everywhere.
Black Monday is sometimes confused with Black Tuesday of 1929. Those names describe different crashes: Black Monday generally means the 1987 event, while Black Tuesday refers to October 29, 1929.