The 24 October 1929 U.S. stock-market collapse is known as Black Thursday.
On that Thursday, panic selling overwhelmed the New York Stock Exchange. A group of leading bankers bought large quantities of heavily traded shares to calm the market, and prices temporarily stabilized. The intervention did not end the underlying weakness.
Black Thursday was followed by renewed selling, including Black Monday on 28 October and Black Tuesday on 29 October. Together, these episodes became central landmarks of the Wall Street Crash, although the market’s decline continued for years afterward.
The crash did not by itself cause every feature of the Great Depression. Falling investment, bank failures, debt problems, reduced trade, and policy choices also mattered. A common mistake is to treat 24 October as the entire crash; it was the first famous panic day in a longer collapse.