Black Thursday was the 1929 trading day remembered as the start of the Wall Street Crash because of heavy selling.
Black Thursday occurred on October 24, 1929, when panic selling caused a sharp decline on the New York Stock Exchange. Trading volume reached a record at the time, and leading bankers attempted to restore confidence by buying heavily traded shares. That intervention briefly steadied prices, but it did not end the crisis.
The market suffered another major collapse on Black Monday, October 28, followed by Black Tuesday, October 29. Black Tuesday is often treated as the crash's most famous day because the Dow Jones Industrial Average lost roughly 12% and trading volume reached another record. The market then continued falling for years.
The crash did not alone cause the Great Depression. It damaged confidence and wealth, while banking failures, reduced demand, debt, and policy choices deepened the economic downturn. The names of the October days can also cause confusion: Black Thursday came first, while Black Tuesday marked the most notorious climax.