That’s because the correlation between crude oil and stocks has not been stable over time. For several decades prior to 2000, for example, that correlation was negative, as you can see in the chart below. During those decades, higher oil prices in a given month led to below-average stock-market returns in the subsequent month.

U.S. oil prices retreated from weekly highs as markets assessed the potential for a reprieve in Middle East turmoil following a week of escalating tensions. The U.S. crude oil price benchmark, West Texas Intermediate,