The sharp U.S. stock-market decline of October 24, 1929, is commonly called Black Thursday.
On Black Thursday, heavy selling hit the New York Stock Exchange after weeks of market weakness. Trading volume reached a then-record level, and the Dow Jones Industrial Average fell sharply during the session. A group of major bankers later attempted to restore confidence by buying leading stocks, and prices temporarily stabilized.
That intervention did not end the crash. Selling returned on the following Monday and intensified on Black Tuesday, October 29. The two later sessions became more famous because the declines were even larger and helped define the public memory of the 1929 collapse.
Black Thursday is therefore a specific date, not another name for the entire Great Depression. The economic depression had many causes, including debt, bank failures, reduced demand, and international financial strain. The stock-market crash was a major accelerator rather than the sole explanation.