What was the name of the 24 October 1929 US stock-market crash day?

The 24 October 1929 US stock-market crash day was called Black Thursday.

On that Thursday, panic selling sent prices sharply lower on the New York Stock Exchange. A group of leading bankers bought major stocks to support prices, temporarily calming the market. The intervention did not end the crisis: further dramatic declines followed on 28 October, called Black Monday, and 29 October, called Black Tuesday.

The Wall Street Crash developed after years of rapidly rising share prices, widespread speculation, and buying stocks with borrowed money. The market had reached a peak in September 1929 before turning downward. The crash damaged confidence and was an important event at the beginning of the Great Depression, although historians identify multiple causes for that worldwide economic disaster.

Black Thursday is therefore not the same date as Black Tuesday. The two names are often mixed up because both belong to the same sequence of October 1929 sell-offs and because Black Tuesday became the most famous label in popular histories.