Black Tuesday, the most famous plunge of the 1929 Wall Street Crash, occurred on October 29, 1929.
On that day, about 16 million shares changed hands on the New York Stock Exchange, a record at the time. Prices collapsed after weeks of mounting fear, heavy speculation, and forced selling by investors who had bought shares with borrowed money.
The crash did not cause the Great Depression by itself, but it became its defining financial symbol. Falling share prices damaged confidence, reduced household wealth, and weakened businesses and banks. The economic downturn deepened through the early 1930s.
Black Thursday, October 24, and Black Monday, October 28, were also important days in the collapse. A common mix-up is treating Black Tuesday as the entire crash; it was the climactic trading day in a broader decline that began in September 1929 and continued afterward.