The Yom Kippur War helped trigger the oil shock that deepened the 1973–74 stock-market crash.
Egypt and Syria attacked Israel on October 6, 1973, beginning the Yom Kippur War. In response to Western support for Israel, Arab members of OPEC imposed an oil embargo on several countries, including the United States, and oil prices rose sharply.
The resulting energy shock contributed to inflation, weaker economic growth, and recession in many industrial economies. Stock markets were already under pressure from monetary tightening, the end of the postwar boom, and the collapse of confidence connected with the Watergate scandal.
The war itself did not mechanically cause every market loss. Instead, it helped produce the oil-price shock that worsened existing economic problems. The bear market that began in 1973 lasted into 1974, and the Dow ultimately lost almost half its value from its 1973 peak.