29 October 1929 is known as Black Tuesday, the final major selling day of the Wall Street Crash.
On Black Tuesday, investors traded roughly 16 million shares on the New York Stock Exchange, a record at the time. Prices collapsed as panic selling spread, wiping out billions of dollars in market value. The Dow Jones Industrial Average fell about 12% that day.
Black Tuesday followed Black Thursday on 24 October and Black Monday on 28 October. Although the crash did not by itself cause the entire Great Depression, it severely damaged confidence, reduced wealth, and contributed to a wider economic contraction.
A common mix-up is treating Black Tuesday as the beginning of the crash. The market had already fallen sharply from its September 1929 peak, and the sell-off continued after 29 October. The date is specifically remembered as the climactic trading session.