October 29, 1929, is known as Black Tuesday during the Wall Street Crash.
On that day, roughly 16 million shares changed hands on the New York Stock Exchange, overwhelming trading systems and intensifying public panic. The Dow Jones Industrial Average fell about 12%, after already suffering a steep decline on Black Monday, October 28.
Black Tuesday did not begin the entire crash. Prices had already weakened after the market peak in September 1929, and the collapse continued for years. The Dow eventually reached its low in July 1932, about 89% below its 1929 peak.
A common mix-up is treating Black Tuesday as the only crash day. Black Thursday, October 24, and Black Monday, October 28, were also major turning points. The 1929 crash helped deepen the Great Depression, although historians identify multiple causes, including falling demand, debt, bank failures, and industrial overproduction.