The highest single-day percentage loss of the Dow during the Wall Street Crash of 1929 was 12.8%.
That decline occurred on October 28, 1929, which became known as Black Monday. The Dow Jones Industrial Average fell sharply as investors reacted to continuing weakness and rushed to sell. The following day, Black Tuesday, brought another enormous fall and record trading volume.
The 1929 crash is often summarized through several dramatic dates: Black Thursday on October 24, Black Monday on October 28, and Black Tuesday on October 29. The percentages differ because each session began from a different index level. This is why the 1929 crash’s largest one-day percentage decline is not the same as the 1987 record.
The market’s collapse harmed confidence and reduced wealth, but the Great Depression also reflected banking failures, deflation, falling production, international debt problems, and policy choices. The crash was a crucial event within a larger economic catastrophe.