The 1929 U.S. stock-market crash's most famous second plunge on October 29 was called Black Tuesday.
Black Tuesday followed Black Thursday, October 24, and Black Monday, October 28. On October 29, 1929, heavy selling overwhelmed the New York Stock Exchange. About 16 million shares changed hands, a record at the time, while the Dow Jones Industrial Average fell nearly 12%. The selling helped turn a severe market decline into the defining crash of the decade.
The crash did not single-handedly cause the Great Depression. Economic weakness, bank failures, falling investment, reduced consumer demand, and policy mistakes all contributed to the depression that followed. The stock market had also risen dramatically during the 1920s, encouraging speculation and purchases made with borrowed money.
A common mix-up is treating Black Tuesday as the entire crash. It was one especially dramatic trading day within a broader collapse that began in September 1929 and continued into 1932.