29 October 1929 was called Black Tuesday, the day the U.S. stock market suffered its largest single-day sell-off of the crash.
The Dow Jones Industrial Average fell about 12% that day, following a fall of roughly 13% on Black Monday, 28 October. Heavy selling overwhelmed the New York Stock Exchange, as investors rushed to unload shares bought during the speculative boom of the 1920s.
Black Tuesday is often treated as the symbolic climax of the Wall Street Crash, although prices continued falling for years. The Dow eventually reached its low in July 1932, about 89% below its September 1929 peak.
A common mix-up is confusing Black Tuesday with Black Thursday, 24 October 1929, when panic selling first became especially prominent. The crash helped intensify the Great Depression, but economists also identify banking failures, declining demand, debt, and policy mistakes as important causes.