The name of the 1929 stock-market crash’s October 29 panic day was Black Tuesday.
On October 29, 1929, investors sold roughly 16 million shares on the New York Stock Exchange. The Dow Jones Industrial Average fell about 12%, intensifying the collapse that had begun with heavy selling on October 24, often called Black Thursday.
Black Tuesday did not single-handedly cause the Great Depression. The crash destroyed enormous paper wealth, weakened confidence, and exposed financial vulnerabilities, while bank failures, falling demand, debt problems, and policy mistakes deepened the subsequent economic contraction.
A common mix-up is calling October 29 Black Monday. In the standard naming convention, October 28, 1929, was Black Monday, while October 29 was Black Tuesday. The Dow continued declining after both days before eventually reaching a low in 1932.