Which U.S. stock index lost nearly 90% from its 1929 peak during the Great Crash?

The Dow Jones Industrial Average lost nearly 90% from its 1929 peak during the Great Crash.

The Dow reached a pre-crash high of 381.17 on 3 September 1929. After the market’s sharp declines in October, it continued falling through the early 1930s and did not regain its 1929 high until November 1954. The long recovery reflected both the stock-market collapse and the wider economic crisis of the Great Depression.

The crash was associated with speculative buying, purchases made on margin, weakening industrial conditions, and a loss of investor confidence. It was not caused by one single trading day. Black Thursday, Black Monday, and Black Tuesday were among the most famous sessions in the October collapse.

The Dow is a price-weighted index of selected major U.S. companies. It is distinct from the broader, capitalization-weighted S&P 500, which was not yet the same modern benchmark in 1929.