The 24 October 1929 Wall Street trading day when heavy selling began the market’s historic collapse is called Black Thursday.
The day followed weeks of nervous trading and falling prices. Panic selling overwhelmed the New York Stock Exchange, and the Dow Jones Industrial Average dropped sharply, although a group of major bankers later bought shares to restore confidence temporarily. That intervention helped stabilize prices for a few days, but it did not end the underlying crisis.
Black Thursday is part of the wider Wall Street Crash of 1929, which also included Black Monday on 28 October and Black Tuesday on 29 October. Those later sessions produced even steeper losses. The crash did not by itself cause the entire Great Depression, but it damaged confidence, reduced wealth, and contributed to a broader economic contraction.
A common mix-up is treating Black Thursday as the single day of the greatest percentage fall. Black Monday and Black Tuesday were later sessions in the same collapse and are associated with larger one-day losses.