What was the October 24, 1929 sell-off on the New York Stock Exchange commonly called?

The October 24, 1929 sell-off on the New York Stock Exchange was commonly called Black Thursday.

The day marked the first major break in the Wall Street crash of 1929. Heavy selling overwhelmed the exchange, and the Dow Jones Industrial Average fell sharply during the session. A group of leading bankers bought large blocks of shares late in the day, helping steady prices temporarily.

The panic returned the following week. October 28 became known as Black Monday, while October 29 became Black Tuesday, when the Dow suffered another severe decline. These labels describe separate days in the same crash, not alternative names for October 24.

The 1929 collapse developed after years of speculative buying, widespread use of borrowed money, and rising concern about the US economy. The crash did not single-handedly cause the Great Depression, but it became its most famous financial symbol.