Which stock-market index lost about 89% of its value during the Wall Street Crash from 1929 to 1932?

The Dow Jones Industrial Average lost about 89% of its value during the Wall Street Crash from 1929 to 1932.

The Dow reached a record closing high of 381.17 on September 3, 1929. After speculative buying, margin debt, weakening economic conditions, and growing concern among investors, prices began to fall. The most famous panic sessions occurred on Black Thursday, October 24, and Black Tuesday, October 29.

The index continued declining after those October sessions and reached a low of 41.22 on July 8, 1932. That represented a fall of roughly 89% from its 1929 peak. The crash was a major financial event, but the broader Great Depression also involved bank failures, deflation, unemployment, and falling industrial output.

The Dow is often mistaken for a complete measure of the U.S. stock market. It is a price-weighted index of selected large companies, whereas later benchmarks such as the S&P 500 cover a broader group. The Dow did not regain its 1929 closing high until 1954.