Donald Trump’s rejection of a diplomatic proposal with Iran sent Brent crude futures sharply higher as markets anticipated renewed Middle East tensions. The price climb reflects concerns over potential supply disruptions and geopolitical risk premiums.

The jump in oil costs triggered a broad selloff in U.S. airline equities, with carriers sensitive to fuel price swings among the hardest hit. Rising jet fuel costs often translate directly into increased operating expenses.

United Airlines shares underperformed peers as investors factored in higher fuel bills, which could erode profit margins if not offset by ticket-price increases or hedging gains. The company’s existing fuel hedges may soften near-term cost pressures but cannot fully shield against sustained price jumps.