Black Tuesday during the 1929 Wall Street Crash was Tuesday, October 29, 1929.
On Black Tuesday, roughly 16 million shares changed hands on the New York Stock Exchange, a record at the time, while the Dow Jones Industrial Average fell about 12 percent. The selling followed Black Thursday on October 24 and Black Monday on October 28, making the crash a sequence of violent market declines rather than a single isolated session.
The market had reached a peak in September 1929 after years of rising share prices and widespread speculation. Falling prices damaged confidence, and investors who had purchased shares with borrowed money faced margin calls. Forced selling added to the downward pressure.
The crash did not by itself cause every feature of the Great Depression, but it helped undermine banks, businesses, and consumer confidence. The Dow continued falling until 1932, when it reached a low far below its 1929 peak.