Which 1973 event intensified the global stock-market crash by restricting oil supplies?

The OPEC oil embargo intensified the global stock-market crash that began in 1973.

In October 1973, Arab members of the Organization of Petroleum Exporting Countries imposed an oil embargo on countries viewed as supporting Israel during the Yom Kippur War. Several oil producers also cut production, and the price of crude oil rose sharply. The disruption contributed to inflation, slower economic growth, and severe pressure on oil-importing economies.

Stock markets were already weakened by monetary uncertainty, poor economic conditions, and the end of the postwar expansion. The energy shock deepened the downturn and helped produce the combination of inflation and stagnation known as stagflation. In the United States, the bear market from 1973 to 1974 became one of the worst postwar market declines.

The embargo did not single-handedly cause every market loss. It was one major factor in a broader economic crisis. The embargo was lifted in March 1974, although oil prices remained much higher than before the crisis.