North American crude sold-off through May as the Iran-war risk premium deflated. Ceasefire optimism and a late-month 60-day memorandum took WTI roughly 16.5% lower over the month, both benchmark futures closing May at their respective lows. OPEC+ adding 188 kbd for June, the UAE's exit, softer Chinese imports, and rising Venezuelan output all reinforced the move.
Differentials confirmed the war premium fading from physical markets: WTI at Corpus, East Houston, and Midland surrendered the wide premiums carried earlier in the month, while deeply discounted grades such as Southern Green Canyon recovered, the complex returning toward normal grade relationships.
The next leg depends on Hormuz transit confirmation: sustained reopening prices out the residual $25-30 risk premium toward $80, while renewed closure tests $108-110.
Market Activity
Even as prices relaxed to more normal levels, trade activity responded month-over-month (m-o-m) to market demand for North American oil.
North American crude spot activity rose 11% month-over-month to more than 2.8 million bpd across key grades. Mars, Canadian Sour at both Cushing and Houston, and Southern Green Canyon together added roughly 150 kbd, claiming a larger share of the traded complex as refiners continued to source heavier domestic barrels to offset reduced Middle Eastern supply.
Midland-quality WTI activity rose across Midland, Houston, and Ex-Basin, though Ex-Basin volume nearly doubled to roughly 103 kbd as the mid-continent drew stronger interest in light barrels, consistent with seasonal refinery run increases with the onset of summer driving demand.
Price Action
The war premium unwound across physical markets: light-sweet grades surrendered their early-month premiums as the ceasefire took hold, while deeply discounted grades recovered ground, SGC climbing from a steep discount toward flat. Mars told a different story, opening the month at an unusual premium, widening further before pulling back, yet still closing above its typical range, a residual bid for heavier barrels that the ceasefire has not fully erased.
Cross-Market Dynamics
Cross-market, USGC refined products were the clearest echo of crude's headline-driven swings in May, delivery period differences notwithstanding. Gasoline and diesel both firmed modestly, 87 conventional rising from $1.82 to $1.88/gal and ULSD from $1.82 to $1.87/gal, while jet fuel was the lone decliner, slipping from $1.90 to $1.89/gal. The flat close obscured more than it revealed: all three products spiked sharply mid-month, jet touching $2.06/gal, before giving back nearly the entire move by month end.
Cross-Regional Dynamics
The WTI Midland export arb to Europe held essentially flat in May. The CIF Rotterdam premium to Dated Brent barely moved, slipping from +$1.10 to +$1.01/bbl, meaning US barrels remained competitive in the European market throughout the month with no meaningful deterioration or improvement in the transatlantic spread. The absolute price rise of $3.15/bbl largely tracked crude's broader move rather than any change in the US-to-Europe relationship.
The Asia picture is more interesting but also more complex. The USGC-assessed WTI Midland price for Singapore delivery rose $5.05/bbl, outpacing the European move, which suggests the long-haul arb to Asia may have improved slightly across the month. The Singapore-assessed WTI Midland was $68.81 at month end versus $63.16 for the USGC-assessed equivalent, a roughly $5.65/bbl spread that reflects freight.
Curve Structure
- Benchmark futures sit in steep front backwardation, ICE HOU (Jul to Oct 2026) falling about $2.50 a month. Cushing light-sweet diffs are flat (Bakken Light Sweet Cushing at -$0.10) and ride that backwardation; Mars is the lone contango grade vs Cushing (+$3.43 to a +$3.85 plateau from M2), though gently backward vs ICE HOU (+$2.78 to +$2.17).
- Heavy-sour and Gulf Bakken carry the front: Canadian Sour Houston tightest at -$4.56, widest at M2 (-$7.79), narrowing to -$6.28; Bakken Beaumont/Nederland +$0.29 prompt to -$3.08. Both price May heavy strength as temporary.
Price Volatility
Volatility stayed elevated but kept normalizing in May. The regime break was March, not February: following the 28 February strikes, prompt CV jumped to 9.6% on NYMEX WTI and 10.2% on ICE HOU as flat price roughly doubled from the mid $60s to the low $90s. It has since eased for two straight months, to 7.8% and 8.4% in April and 6.1% and 6.5% in May. Even after that pullback, May still runs near triple the calm 1.5 to 2.3% band that held through late 2025 and again in February, with January (4.1%) already stirring ahead of the break. Hedging and VaR models calibrated to that sub-3% regime continue to understate tail risk, and that gap will not close until Hormuz normalizes and the geopolitical premium drains out of the front.
Something To Watch
- Prompt structure: WTI East Houston flat price, as an example, compressed from about $35 front-to-back (M1 to M24) on 18 May to about $16 late month, a $21 prompt sell-off against a near-static back end, the first sign near-term premium is eroding. Watch the roll and prompt-to-CMA spreads through the summer months.
- Hormuz is the binary. The strait has been closed or only partially open since Iran shut it after the 28 February strikes; the fragile April ceasefire holds, but the late-May framework to de-mine and reopen it (a 60-day extension) is still unratified and could collapse. A clean reopening extends the light-sweet compression as waterborne supply and risk premium drain from the front. A breakdown re-inflates the premium across the curve and widens the Mars premium most, since shut-in Gulf sour keeps domestic medium-sour bid.
Note: All figures, prices and market activity referenced in this report are based on the period 1 to 26 May 2026.
