Black Thursday is the nickname for October 24, 1929, the trading day when heavy selling first signaled the Wall Street Crash.
The New York Stock Exchange saw approximately 12.9 million shares traded that day, then an extraordinary volume. Prices fell sharply in the morning, but a group of leading bankers bought shares in an attempt to restore confidence. That intervention temporarily steadied the market, although it did not end the underlying collapse.
The panic returned with even greater force on Black Monday and Black Tuesday, October 28 and 29. Because all three names are associated with the same crash, dates are important: Black Thursday was October 24, Black Monday was October 28, and Black Tuesday was October 29. The market later fell much further, reaching its 1929–32 low nearly three years afterward.