The 29 October 1929 New York stock-market crash is commonly known as Black Tuesday.
Black Tuesday followed Black Thursday, 24 October, and the especially severe selling on Black Monday, 28 October. On 29 October, about 16 million shares changed hands on the New York Stock Exchange, then a record, while the Dow Jones Industrial Average fell sharply.
The crash did not by itself create every hardship of the Great Depression, but it destroyed enormous paper wealth and damaged public confidence. Banks, companies, and households were already vulnerable because of speculation, buying shares on margin, and weakening economic conditions.
A common mix-up is treating Black Tuesday as the entire 1929 crash. It refers specifically to the dramatic Tuesday session, whereas the broader Wall Street Crash unfolded across several weeks. The market eventually fell much further, reaching its major low in July 1932.