Black Tuesday was the October 29, 1929, trading day with the largest point drop in the Dow Jones Industrial Average during the Wall Street crash.
On Black Tuesday, roughly 16 million shares changed hands, then an extraordinary volume for the New York Stock Exchange. The Dow fell nearly 12%, following major losses on Black Thursday, October 24, and Black Monday, October 28. The sequence shattered public confidence in stocks and helped end the speculative boom of the 1920s.
The crash did not by itself cause the entire Great Depression, but it was an important warning and financial shock. Bank failures, falling demand, debt problems, deflation, and policy mistakes deepened the later economic contraction. The Dow continued declining after October 1929 and did not regain its earlier peak until 1954.
Black Tuesday is often used as shorthand for the whole crash, although the Wall Street collapse lasted longer than one session. Black Thursday and Black Monday were also major days in the same episode.