What was the name of the 1929 crash's first major day of panic on October 24?

The first major panic day of the 1929 crash, October 24, was called Black Thursday.

On Black Thursday, selling pressure overwhelmed the New York Stock Exchange. The Dow Jones Industrial Average lost about 11% of its value at the opening, and approximately 12.9 million shares changed hands—a record at the time. The ticker tape fell hours behind actual trading, leaving many investors unaware of current prices as they tried to sell.

Leading bankers then coordinated purchases of major stocks to signal confidence and slow the panic. Their intervention helped produce a temporary recovery, but it did not end the underlying collapse. Selling intensified again on October 28, known as Black Monday, and reached another historic peak on October 29, Black Tuesday.

Black Tuesday is therefore the date most often associated with the crash’s climax, not its first major panic. Black Friday is usually associated with post-Thanksgiving retail shopping and is unrelated to the 1929 market episode. The crash continued to weigh on confidence and was followed by a prolonged decline; the Dow eventually reached its twentieth-century low in July 1932.