The 29 October 1929 U.S. stock-market crash is known as Black Tuesday.
Black Tuesday followed Black Thursday, the panic-selling session on 24 October, and Black Monday, 28 October. On 29 October, about 16 million shares changed hands on the New York Stock Exchange, then an extraordinary volume, while the Dow Jones Industrial Average fell about 12.8%.
The crash did not single-handedly cause the Great Depression. It followed years of speculative buying, widespread use of borrowed money, weakening economic conditions, and fragile banks. The downturn then deepened through bank failures, falling production, and unemployment.
A common mix-up is treating Black Tuesday as the entire crash. Historians usually describe the Wall Street Crash of 1929 as a sequence of severe sessions in late October, with Black Tuesday serving as its most famous date.