NEW YORK — Spot ethylene on the U.S. Gulf Coast fell almost 17 percent last week, its third consecutive weekly decline, as the surge in export demand that followed the outbreak of the Iran war gave way to a quieter June order book. Polymer-grade propylene, or PGP—a feedstock for polypropylene used in automotive parts, textiles and containers—dropped about 8 percent, its fourth straight week of declines or flat pricing.
Traders attribute the pullback to weakening June export demand. For months, the conflict in Iran disrupted global oil and chemical trade flows, pushing buyers toward low-cost U.S. feedstocks and plastic resins. That demand surge sent U.S. Gulf Coast ethylene exports to approximately 83,000 barrels a day in May—the highest level of 2026 and a 46 percent increase from April loadings, according to shipment data from analytics firm Kpler.
The May export spike now looks like the peak of the Iran-war premium rather than a new baseline. Export demand redirected to the Gulf Coast during the disruption is pulling back, and the result is a broad softening across petrochemical spot prices rather than a single commodity move.
Ethylene is the foundational building block for polyethylene plastics found in packaging and consumer goods. A sustained drop in its spot price compresses margins for Gulf Coast steam crackers—the facilities that convert ethane into ethylene and propylene. Cracker margins had expanded sharply during the Iran-driven price surge; that expansion is now unwinding as spot olefin prices fall faster than feedstock costs adjust.
On the feedstock side, ethane—the key input for ethylene production—ended the week slightly higher at about 21 cents a gallon. That move runs counter to the direction of the products crackers produce, narrowing the spread between input cost and output price. Higher ethane with lower ethylene is the margin-compression trade that cracker operators have been watching tighten.
The disruption around the Strait of Hormuz had amplified feedstock costs globally. Roughly half of LPG exports moving through the strait feed into petrochemical demand, according to data from the International Energy Agency. With that choke point under stress, buyers outside the United States faced higher landed costs for competing feedstocks, making U.S. Gulf Coast ethane-based production temporarily the cheapest source of olefins in the world.
That structural advantage has not disappeared. U.S. feedstocks remain competitive even after the Iran premium unwinds, because domestic ethane production is tied to natural gas output rather than crude oil pricing. At 21 cents a gallon, ethane sits well below the cost of naphtha—the dominant petrochemical feedstock in Europe and Asia—keeping Gulf Coast crackers in a favorable position on a cost-per-unit basis even as spot olefin prices retreat.
The concern for Gulf Coast producers is the demand side, not the cost side. Export volumes that reached 83,000 barrels a day in May were driven by buyers pulling forward purchases ahead of anticipated supply disruptions. That front-loading likely satisfied a portion of June demand before June arrived, leaving fewer open orders now. The question for the back half of the summer is whether underlying demand is strong enough to absorb current production levels at prices that support cracker profitability.
Operational issues along the Gulf Coast helped limit steeper declines last week. Unplanned outages and maintenance events at multiple facilities reduced available spot supply, providing a partial floor under prices that would otherwise have moved lower more quickly. The pace of decline in subsequent weeks will depend in part on how quickly that lost production returns to the market.
PGP's four-week streak of declines or flat pricing carries a separate set of implications. Polypropylene end markets—automotive parts, fiber and rigid containers—do not respond to spot price swings as quickly as commodity packaging films. Automotive buyers in particular negotiate on quarterly contracts, meaning a sustained PGP move takes time to feed through to production costs. If PGP spot prices hold lower through June, contract negotiations for the third quarter could shift in buyers' favor.
The bond market reads commodity deflation through a specific lens: falling petrochemical prices reduce input costs across a wide swath of manufacturing, which shows up with a lag in producer price indexes and eventually in core goods components of CPI. The Federal Reserve's preferred inflation gauge, core PCE, has been sticky on the services side. Any relief from goods deflation—amplified by softening petrochemicals, packaging costs and industrial inputs—would provide marginal downward pressure on the overall index without requiring any change in services dynamics. That is a small but real tailwind for the rate path if the petrochemical retreat holds into July data.
