What was the largest one-day percentage fall in the Dow before 1987, during the 1929 Wall Street Crash?

Black Monday, October 28, 1929, brought the largest one-day percentage fall in the Dow before 1987.

The Dow Jones Industrial Average dropped 38.33 points, or 12.82 percent, on October 28. The next day, Black Tuesday, brought another enormous decline as panic selling continued. Together, the two sessions marked the most dramatic phase of the Wall Street Crash of 1929.

The market had risen rapidly during the 1920s, encouraging widespread speculation and buying on margin. When prices began falling, investors faced demands for additional cash and were forced to sell. That process increased downward pressure and undermined confidence.

Black Monday is often overlooked because Black Tuesday is more famous. The two dates are distinct, however: October 28 produced the larger percentage decline, while October 29 produced the larger trading volume and became the crash’s best-known label.