Black Tuesday, the final major crash day of 1929, occurred on October 29, 1929.
On that Tuesday, investors traded roughly 16 million shares on the New York Stock Exchange, an enormous volume for the period. The Dow Jones Industrial Average fell about 12%, following a 13% drop on Black Monday, October 28.
The crash did not cause the Great Depression by itself. It followed years of speculative buying, widespread use of borrowed money, weakening industrial conditions, and falling consumer demand. The market continued declining after October 29, reaching a major low in July 1932.
A common mix-up is treating Black Tuesday as the only crash day. Black Thursday, October 24, began the dramatic selling, while Black Monday and Black Tuesday produced the sharpest consecutive losses. The 1929 collapse also differed from the 1987 crash, which was much more concentrated in a single day.