Black Tuesday occurred on October 29, 1929, during the Wall Street Crash of 1929.
The Dow Jones Industrial Average fell 11.7% that day as investors sold roughly 16 million shares on the New York Stock Exchange. The previous Thursday, October 24, is remembered as Black Thursday, while Monday, October 28, brought another exceptionally severe decline.
The crash followed years of rapidly rising share prices, widespread speculation, and extensive use of borrowed money to buy stocks. The collapse did not by itself cause the entire Great Depression, but it severely damaged confidence and helped intensify the economic downturn.
Black Tuesday is often treated as the single defining date of the crash, although the market continued falling after October 29. The Dow did not regain its September 1929 peak until 1954.