Which 1929 stock-market day saw the largest trading volume recorded up to that time?

The 1929 stock-market day that saw the largest trading volume recorded up to that time was Black Tuesday.

Black Tuesday occurred on October 29, 1929, during the Wall Street Crash. Panic selling overwhelmed the New York Stock Exchange, and about 16 million shares changed hands, a record at the time. Prices fell sharply as investors tried to exit positions simultaneously.

Black Tuesday followed Black Thursday on October 24 and Black Monday on October 28. Although the crash unfolded across several sessions, October 29 became its most famous date. The Dow Jones Industrial Average fell about 12 percent that day.

The crash did not by itself cause every feature of the Great Depression, but it destroyed wealth and confidence and intensified economic weakness already present in the United States. The Dow continued falling until 1932, when it reached a low far below its 1929 peak.