October 24, 1929, was the date of the first major sell-off of the 1929 Wall Street crash at the New York Stock Exchange.
The day became known as Black Thursday. Heavy selling overwhelmed the exchange, and the Dow Jones Industrial Average dropped sharply amid extremely high trading volume. A group of leading bankers later met and bought major stocks in an attempt to restore confidence, temporarily stabilizing prices.
That intervention did not end the crisis. Selling returned the following week, with Black Monday on October 28 and Black Tuesday on October 29. The Dow’s decline continued for years, reaching its eventual low in July 1932. The crash was one part of the wider economic catastrophe known as the Great Depression, although historians debate how much the crash itself caused versus reflected underlying economic weakness.
Black Thursday is therefore the opening day of the most famous sequence of 1929 crash sessions, not the final market low.