October 29, 1929, was called Black Tuesday, the day the U.S. stock market suffered its most famous crash-era sell-off.
Nearly 16 million shares changed hands on the New York Stock Exchange, a record at the time. The Dow Jones Industrial Average fell about 12%, following a 13% drop on Black Monday, October 28.
Black Tuesday did not single-handedly cause the Great Depression. The crash exposed severe speculation, buying on margin, weak banking practices, and slowing economic conditions. It was part of a broader collapse that continued into 1932, when the Dow reached its low for the period.
A common mix-up is confusing Black Tuesday with Black Thursday, October 24, the first major panic day of the 1929 crash. Black Monday and Black Tuesday together produced the most dramatic losses of that week.