The 1929 U.S. stock-market crash day associated with October 29's huge trading volume was called Black Tuesday.
On October 29, 1929, investors sold roughly 16 million shares on the New York Stock Exchange, and stock prices plunged. The session followed Black Thursday, October 24, and Black Monday, October 28, during a chaotic week of selling. The market's collapse continued after October 29 rather than ending instantly that day.
The crash marked the beginning of the most famous financial collapse of the twentieth century, although the ensuing Great Depression had many causes. Bank failures, reduced lending, falling demand, industrial contraction, and international economic problems all deepened the downturn.
A common mistake is to treat Black Tuesday as the entire Depression. It was a dramatic market event, but the Great Depression lasted for years and involved the wider economy. The Dow Jones Industrial Average did not recover its pre-crash peak until 1954.