The 1929 Wall Street trading session known for its enormous selling wave was Black Tuesday.
Black Tuesday occurred on October 29, 1929, when roughly 16 million shares changed hands on the New York Stock Exchange. The Dow Jones Industrial Average fell about 12%, extending the severe declines that had begun the previous week. The session followed Black Thursday on October 24 and Black Monday on October 28.
The crash did not single-handedly cause the Great Depression, but it became its most famous financial symbol. The wider economic downturn also involved falling production, bank failures, debt problems, unemployment, and collapsing international trade.
Black Tuesday is often treated as the single start of the Depression, although historians generally describe the crash as one event within a broader sequence. It is distinct from Black Thursday, the earlier October 24 session, and from Black Monday in 1987.