What was the nickname of the severe US stock-market decline on 28 October 1929?

The severe US stock-market decline on 28 October 1929 was nicknamed Black Monday.

On that day, the Dow Jones Industrial Average fell 38.33 points, or about 12.8%, then the largest percentage decline in its history. The loss came after renewed selling pressure following the previous week’s turmoil. A further collapse occurred on 29 October, which became known as Black Tuesday.

The 1929 crash did not by itself create every condition of the Great Depression, but it severely damaged confidence and helped deepen the economic downturn. Banks, businesses, and households became more cautious, while falling share prices reduced wealth and investment.

The event is sometimes described as a single-day disaster, but the Wall Street Crash unfolded across several trading sessions. Black Thursday occurred on 24 October, Black Monday on 28 October, and Black Tuesday on 29 October. These labels are calendar-based and should not be confused with the 1987 global crash, also widely called Black Monday.