The 1929 U.S. stock-market collapse day on October 29 was called Black Tuesday.
Black Tuesday followed Black Thursday, October 24, and Black Monday, October 28, during a period of frantic selling on the New York Stock Exchange. On October 29, roughly 16 million shares changed hands, a record at the time, and the Dow Jones Industrial Average fell about 12.8 percent.
The crash did not by itself cause every part of the Great Depression, but it sharply damaged confidence, reduced wealth, and exposed weaknesses in banks, businesses, and the wider economy. Stock prices had risen dramatically during the 1920s, helped by speculation and buying shares with borrowed money.
A common mix-up is treating Black Tuesday as the whole crash. The Wall Street Crash unfolded across several days in October 1929, while the economic depression deepened over the following years. The Dow did not regain its September 1929 peak until 1954.