Which U.S. stock index fell nearly 90% during the Wall Street Crash of 1929?

The Dow Jones Industrial Average ultimately fell nearly 90% from its 1929 peak during the Wall Street Crash.

The Dow reached a pre-crash high in September 1929 before falling dramatically through October and November. It did not reach its eventual low until July 1932, when it was roughly 89% below the peak. That long decline is why the crash is usually discussed as part of a wider bear market.

The best-known panic dates were Black Thursday, 24 October, and Black Tuesday, 29 October 1929. Heavy selling, margin buying, weakening economic conditions, and highly speculative share valuations all contributed to the disaster.

The Dow measured only a small group of industrial companies, so it was not a complete measure of every share. The S&P 500 did not yet exist in its modern form; it was introduced in 1957.