Black Thursday was the nickname of the first major Wall Street crash day in October 1929, before Black Tuesday.
On October 24, 1929, heavy selling overwhelmed the New York Stock Exchange. The Dow Jones Industrial Average fell sharply, and trading volume reached a then-record level. Leading bankers later attempted to stabilize prices by buying major stocks, producing a temporary recovery during the session.
That intervention did not end the crisis. Selling returned the following week, with Black Monday on October 28 and Black Tuesday on October 29 becoming even more destructive sessions. The crash damaged confidence and helped deepen the economic contraction that became the Great Depression.
Black Thursday is not the same as Black Tuesday. Both names refer to separate trading days in the same historic 1929 collapse.