What was the name of the first major sell-off during the Wall Street Crash of 1929?

The first major sell-off during the Wall Street Crash of 1929 was called Black Thursday, October 24, 1929.

On that day, almost 13 million shares changed hands on the New York Stock Exchange, a record at the time. The Dow Jones Industrial Average opened sharply lower, and intense selling created fear that the market’s long boom had ended.

A group of prominent bankers intervened by buying heavily near the market’s low. Their purchases temporarily stabilized prices and helped calm the exchange, but the relief did not last. Renewed selling returned the next week, leading to Black Monday on October 28 and Black Tuesday on October 29.

Black Thursday was not the single largest percentage fall of the crash. Its importance comes from its role as the first dramatic break in the final autumn collapse. The event is also separate from the 1907 panic, which helped inspire later financial reforms.