U.S. stock markets experienced a significant drop on Thursday, as investors began factoring in the repercussions of escalating conflict in the Middle East. This shift came after Brent Crude oil prices surged past $100 per barrel, triggered by ongoing U.S. military strikes against Iran for 12 nights and reported attacks on tankers near Saudi Arabia. Although equities had previously shown resilience despite rising oil prices and Treasury yields, the renewed tensions and rising energy costs prompted a more cautious stance from market participants.

The surge in oil prices is substantial, with Western Texas Intermediate Crude futures climbing 6% to reach $92 per barrel, marking a more than 28% increase from earlier lows in July. The S&P 500 has declined roughly 2% since the strikes began mid-month, reflecting growing concerns about the economic cost of a prolonged conflict. This market reaction echoes March’s volatility when the U.S.-Iran war initially sparked fears of stagflation, as oil prices soared nearly 70%, potentially pressuring consumer spending and inflation simultaneously.

Market strategists point to multiple factors intensifying investor apprehension, including higher inflation expectations and tighter borrowing conditions. With the 10-year Treasury yield surpassing 4.7%, the highest since January 2025, and the likelihood of Federal Reserve interest rate hikes rising, companies could face costlier financing. Analysts like Steve Sosnick of Interactive Brokers emphasize the difficulty for markets to ignore these signals, which have begun to weigh heavily on stock valuations.

Some investors had previously bet on a diplomatic resolution to the conflict, especially under President Donald Trump’s administration, hoping for an off-ramp that would ease geopolitical tensions and support equities. However, with hostilities persisting, strategists like Wells Fargo’s Sameer Samana warn of a possible retreat in stocks as inflation pressures and the impact of higher gas prices on consumers become more apparent. Despite short-term headline volatility, experts like Michael Tanney of Pereon Wealth suggest that a sustained oil price above $120 per barrel would be the critical threshold for serious economic fallout.