Black Tuesday was October 29, 1929, the day massive selling struck the New York Stock Exchange during the Wall Street Crash.
About 16 million shares changed hands, setting a trading-volume record that stood for decades. Prices collapsed as investors rushed to sell, often accepting sharply lower bids. The session followed Black Thursday on October 24 and another severe decline on Black Monday, October 28.
The crash did not single-handedly cause the Great Depression. Economic weakness, bank failures, falling investment, international debt problems, and policy decisions all helped turn a stock-market collapse into a prolonged global depression.
Black Tuesday is sometimes used as if it names the entire crash, but it specifically refers to the October 29 session. The Dow continued declining after that date, reaching its eventual 1932 low nearly three years later.