The 1929 New York trading day when a record 12.9 million shares were traded was Black Thursday, October 24, 1929. It was the first major panic day of the Wall Street Crash.
Heavy selling overwhelmed the New York Stock Exchange, and the Dow Jones Industrial Average fell sharply. A group of prominent bankers, including Richard Whitney of J.P. Morgan, attempted to stabilize prices by buying selected stocks. Their intervention helped the market recover part of its loss by the close.
The temporary recovery did not end the crisis. Selling returned on Black Monday, October 28, and intensified on Black Tuesday, October 29. The sequence showed that the market’s underlying confidence remained badly damaged.
Black Thursday is often overshadowed by Black Tuesday, but it marked the public beginning of the most famous phase of the 1929 crash. The 12.9 million-share figure was a trading-volume record for its era.