The first major panic day of the 1929 stock-market crash was called Black Thursday, on October 24, 1929.
Selling accelerated that morning on the New York Stock Exchange after weeks of falling prices. The market's decline was briefly moderated by a group of leading bankers who bought large blocks of shares, but the intervention did not end the broader collapse.
The crash continued with Black Monday on October 28 and Black Tuesday on October 29. On Black Tuesday, approximately 16 million shares changed hands, a record at the time. The market then lost most of its value over the following years, reaching a low in 1932.
Black Thursday is not the same as Black Tuesday, even though both belong to the same crash. The names refer to separate trading days in the sequence of the 1929 panic.