The October 29, 1929, peak day of the Wall Street Crash is commonly called Black Tuesday.
On that day, about 16 million shares changed hands on the New York Stock Exchange, a record at the time. The Dow Jones Industrial Average fell 12%, following the severe losses of Black Thursday, October 24, and Black Monday, October 28.
The crash followed years of rapid speculation and heavy buying on margin. Many investors borrowed money to purchase shares, so falling prices created demands for additional collateral and forced more sales. Bank failures, reduced lending, and weakening economic activity deepened the wider downturn.
Black Tuesday was dramatic, but it was not the only important date in the crash. The Dow continued falling after October 1929 and reached its low in July 1932, when it stood roughly 89% below its September 1929 peak. The crash became a defining early event of the Great Depression.