The October 24, 1929 sell-off that preceded Black Tuesday in the Wall Street Crash was called Black Thursday.
On Black Thursday, roughly 12.9 million shares were traded on the New York Stock Exchange, then an extraordinary volume. Prices plunged in the morning, but a group of major bankers intervened by buying leading stocks and temporarily steadied the market. That intervention helped prevent an even sharper immediate collapse, although it did not solve the underlying problems.
The market became unstable again the following week. Black Monday, October 28, brought another severe decline, and Black Tuesday, October 29, produced the crash’s most famous selling wave. The sequence showed how quickly margin calls and fear could overwhelm attempts to restore confidence.
The crash followed a speculative boom in which stock purchases were often financed with borrowed money. When prices fell, investors had to provide more cash or sell holdings, creating a feedback loop. Black Thursday therefore refers to the first major public shock of the late-October collapse, not the final bottom of the market.