Black Monday was the 1929 market crash’s worst trading day by percentage loss, when the Dow fell nearly 13%.
On October 28, 1929, the Dow Jones Industrial Average dropped 12.8 percent. Selling intensified again on October 29, known as Black Tuesday, when the Dow fell another 11.7 percent. Together, those sessions marked the most dramatic stage of the Wall Street Crash of 1929.
The crash followed a long period of speculation and margin buying. Investors purchased shares with borrowed money, so falling prices forced additional selling when brokers demanded more collateral. The market’s collapse damaged confidence and helped deepen the economic contraction that became the Great Depression.
Black Monday in 1929 is distinct from Black Monday in 1987, which occurred on October 19 and produced a much larger one-day percentage decline. The repeated nickname refers to different crashes in different historical periods.