Black Thursday was the nickname of October 24, 1929, when heavy selling overwhelmed buyers on Wall Street.
The Dow Jones Industrial Average had already fallen from its September peak, but the session on October 24 brought unusually intense selling. The ticker system lagged far behind trading, so many investors did not immediately know the latest prices. A group of leading bankers met at J. P. Morgan & Co. and announced a pooled stock-buying effort, which temporarily steadied the market.
The intervention did not end the crash. Selling returned on the following Monday and Tuesday, and the Dow continued falling for years before reaching its low in 1932. Black Thursday is sometimes confused with Black Tuesday, the later day that became associated with the deepest public shock. The 1929 crash was followed by the Great Depression, although historians identify many economic and financial causes rather than one single trigger.