What name is given to the catastrophic Wall Street sell-off that began on Black Thursday in October 1929?

The catastrophic Wall Street sell-off that began on Black Thursday in October 1929 is called the Wall Street Crash of 1929.

The crash followed a long rise in U.S. share prices during the 1920s. Investors increasingly bought stocks on margin, borrowing money to purchase securities. That practice amplified gains during the boom but made the market vulnerable when prices turned downward. Warning signs appeared before the final October panic, including falling industrial production and weakness in some heavily traded shares.

On October 24, 1929, known as Black Thursday, trading volume surged and prices dropped sharply before a group of bankers attempted to stabilize the market. Selling intensified on October 28, Black Monday, and October 29, Black Tuesday. The Dow Jones Industrial Average lost nearly 13% on Black Monday and nearly 12% on Black Tuesday.

The crash did not by itself cause every aspect of the Great Depression, but it severely damaged confidence and wealth. Bank failures, deflation, falling production, and unemployment deepened the economic crisis during the 1930s.