U.S. refiner stocks have more than doubled in 2026, led by Valero Energy, which rose 2.3% to $391.61 Tuesday and reached a 140.6% year-to-date gain, exceeding its roughly 128% increase in 2005. Refining markets have tightened as the Hormuz disruption, the war in Ukraine, Russian export bans after drone strikes and winter restocking reduced fuel availability; more than 7 million barrels per day of refined-product flows are offline across the Middle East and Russia. The U.S. ultra-low-sulfur diesel crack spread rose to about $106 a barrel from $33 in January, while Phillips 66, Marathon Petroleum and Valero reported second-quarter earnings above consensus, more than doubled per-barrel refining margins and returned over $5 billion to shareholders. Analysts and industry executives describe the disruption as a supply shock rather than a demand shock and expect elevated margins to persist through year-end and potentially into next year, although normalization could take longer than after the 2022 Russian invasion of Ukraine.