Black Tuesday, the most famous day of the 1929 Wall Street Crash, occurred on October 29, 1929.
On that Tuesday, about 16 million shares changed hands on the New York Stock Exchange, then an extraordinary volume. Prices fell sharply as investors rushed to sell, following major declines on Black Thursday and Black Monday. The crash shattered confidence in the booming market of the 1920s.
The collapse did not single-handedly cause the Great Depression, but it weakened banks, businesses, and investors. Economic contraction, bank failures, falling production, and unemployment continued for years afterward. The market also kept declining after October 29.
Black Tuesday is sometimes treated as the entire crash, but it was one particularly dramatic day within a broader episode. Black Thursday refers to October 24, while Black Monday refers to October 28, 1929.