The 1929 trading day commonly called Black Tuesday was October 29, 1929.
On that date, roughly 16 million shares changed hands on the New York Stock Exchange, setting a trading-volume record that stood for decades. Prices fell heavily as investors rushed to sell, following major declines on Black Thursday, October 24, and Black Monday, October 28.
The crash did not by itself cause every feature of the Great Depression, but it became its best-known financial symbol. Weaknesses included excessive borrowing to buy shares, overproduction in parts of the economy, bank failures, and reduced demand. Black Tuesday is sometimes confused with Black Thursday, the first major panic day in the sequence. The broader Wall Street Crash refers to the series of collapses and market weakness that began in October and continued into the early 1930s.