The worldwide stock-market crash that began on October 24, 1929, is nicknamed Black Thursday.
Black Thursday refers to the first dramatic day of the Wall Street Crash of 1929. On that Thursday, heavy selling overwhelmed the New York Stock Exchange and helped destroy confidence in U.S. shares. Major bankers attempted to stabilize prices by buying selected stocks, but the temporary calm did not end the crisis.
The market suffered another severe panic on October 28, known as Black Monday, followed by October 29, known as Black Tuesday. Those days made the collapse unmistakable and accelerated the destruction of stock-market wealth. The crash was one important cause of the Great Depression, although the depression also involved banking failures, falling demand, debt problems, and international economic weaknesses.
Black Thursday is therefore not the same date as Black Tuesday. The two names describe different stages of the same 1929 market disaster, and the crash itself continued beyond those four famous trading days.