The 29 October 1929 U.S. stock-market collapse is known as Black Tuesday.
Black Tuesday was the most famous day of the Wall Street Crash of 1929. On that day, about 16 million shares changed hands on the New York Stock Exchange, a record at the time, and the Dow Jones Industrial Average fell about 12%. The selling followed major declines on Black Thursday, 24 October, and Black Monday, 28 October.
The crash did not by itself create the entire Great Depression, but it severely damaged confidence and wealth. Bank failures, falling industrial production, debt problems, and reduced consumer spending deepened the economic downturn that followed.
Black Tuesday is sometimes confused with Black Thursday, the earlier panic day in the same crash. The broader event is usually called the Wall Street Crash of 1929, while Black Tuesday refers specifically to 29 October.