The Trading Economics Crack Spread Index—which measures the difference between crude oil prices and the value of refined products for the average U.S. refinery—soared to a record high of $75 per barrel in September 2026. This represents an increase of nearly 200% since mid-February, before the United States escalated its threats of strikes on Iran.
The ensuing conflict triggered naval blockades that effectively halted crude oil exports from GCC countries through the Persian Gulf. This disruption sharply curtailed crude feedstock supplies to refineries in major oil‑importing nations and forced U.S. refiners to operate above 100% of nameplate capacity.
The resulting spike in domestic gasoline and diesel prices led the presidential administration to consider imposing a ban on diesel exports. Nevertheless, crack spreads remained at record highs. Markets grew increasingly concerned that any curtailment of U.S. diesel exports would undermine global diesel consumption patterns and, in turn, cloud the outlook for gasoline production. With Gulf Coast and West Coast refineries lacking sufficient flexibility to shift yields toward gasoline, the constraints threatened to reduce overall crude runs.
