The Wall Street Crash’s Black Tuesday occurred on 29 October 1929, when panic selling overwhelmed the New York Stock Exchange.
More than 16 million shares changed hands that day, then a record volume. The Dow Jones Industrial Average fell about 12%, following major declines on Black Thursday, Black Monday, and Black Tuesday itself. The market had reached a peak in early September before entering a steep collapse.
The crash followed years of speculation, widespread use of borrowed money, and rapid growth in share prices during the 1920s. It did not by itself cause every feature of the Great Depression, but it severely damaged confidence and wealth and helped deepen the economic downturn.
Black Tuesday is sometimes treated as the single start of the Great Depression. In reality, the Depression developed through interacting banking, industrial, monetary, and international problems. The stock-market collapse was a major landmark, not the entire explanation.