January 11, 1973, marked the start of the 1973–74 U.S. stock market crash because the Dow Jones Industrial Average peaked that day.
The Dow closed at 1,051.70 on January 11, 1973, beginning a prolonged bear market rather than a single-session collapse. By December 1974, the index had fallen to about 577, representing a loss of roughly 45% from its peak.
The decline unfolded amid high inflation, economic weakness, the 1973 oil crisis, and political uncertainty associated with the Watergate scandal. The end of the Bretton Woods monetary system also formed part of the broader financial background.
Calling January 11 the start does not mean every market fell continuously from that date. Markets moved up and down during the period. The date identifies the Dow's cycle high used to measure the crash, while the later trough identifies its eventual low.