The stock-market collapse on October 24, 1929, the first major selling day of the Wall Street Crash, is called Black Thursday. Heavy selling overwhelmed the New York Stock Exchange, and roughly 12.9 million shares changed hands, a record at the time.
Prices had risen dramatically during the 1920s, encouraged by speculation and widespread buying on margin. On Black Thursday, leading bankers attempted to restore confidence by purchasing large blocks of major stocks. That intervention briefly steadied the market, but the decline resumed the following week.
Black Thursday was followed by Black Monday on October 28 and Black Tuesday on October 29. The crash did not single-handedly create the Great Depression, but it damaged wealth, confidence, and financial institutions while worsening an already fragile economy. The separate 1987 crash is also associated with Black Monday, so the date is essential when identifying this term.