Black Tuesday saw the largest number of shares traded on the New York Stock Exchange at that time during the 1929 crash.
On 29 October 1929, about 16 million shares changed hands on the exchange, a record that stood for decades. Prices collapsed as investors rushed to sell, and the Dow Jones Industrial Average fell nearly 12% that day.
Black Tuesday followed Black Thursday on 24 October and a temporary rebound on the following trading days. The continuing sell-off destroyed confidence and contributed to the broader economic contraction that became the Great Depression.
The crash did not by itself cause every feature of the Depression, and historians identify several additional factors, including bank failures, reduced demand, and international monetary problems. Black Tuesday is specifically the 29 October trading session, not the 24 October session often called Black Thursday.