Which 1929 crash index lost almost 90% of its value before reaching its low in July 1932?

The Dow Jones Industrial Average lost almost 90% from its 1929 peak before reaching its low in July 1932.

The Dow peaked at 381.17 on September 3, 1929. After the autumn panic, continued bank failures, falling production, deflation, and shrinking investment drove the index much lower. It reached 41.22 on July 8, 1932, a decline of roughly 89% from the peak.

The crash was a crucial early event in the Great Depression, but it did not single-handedly create every condition of the depression. The economic collapse involved monetary contraction, banking distress, international debt problems, reduced trade, and policy decisions in many countries.

The Dow eventually recovered its 1929 peak only in November 1954. This long recovery period is why the 1929 episode is often compared with later crashes, even though modern market structures, regulation, and central-bank responses differ substantially.