Gasoline flat price fell through May (CARBOB Los Angeles −20.5% open-to-close, USGC CBOB Pasadena −15.8%), but the move was a crude story, not a gasoline one: the RBOB NYH–Dated Brent crack averaged $37.17/bbl versus April's $13.34/bbl (+179% MoM), peaking at $42.84/bbl on 11 May before easing to a $33.78/bbl final-week average. Gasoline outperformed crude into the driving-season ramp; the margin, not the screen, is where the month happened. Crack volatility collapsed alongside (May daily CV 10.7% vs April's 113%), signalling the violent March-April crack transition resolved into a high, stable summer range rather than a spike. The premium-regular octane spread on CARBOB widened within May from +$0.11 to +$0.26/gal (month average +$0.276/gal), consistent with octane scarcity into summer blending, while the West Coast premium over USGC compressed from +$0.67 to +$0.44/gal as Gulf gasoline firmed (CBOB +7.5% MoM) and the WC eased. The NYH barge basis to NYMEX flipped to a +$0.065/gal screen premium on the final session after a month at a discount, an early sign of East Coast prompt firmness. With the crack establishing a ~$37/bbl floor entering hurricane season (1 June) and driving season, crack sustainability and the NYH basis are the things to watch.
Price Trends
Flat price fell 16-20% open-to-close on a softer crude tape, while the crack tripled; the story is margin, not screen.
- CARBOB LA opened $4.1452/gal (1 May), closed $3.2944/gal (29 May), −20.5% open-to-close; May average $3.8616/gal vs April $3.8517/gal (+0.3% MoM, effectively flat on average despite the within-month slide).
- CARBOB high $4.2882/gal (4 May), low $3.2944/gal (29 May); the low was the close, with declines accelerating to −10.8% in the final week.
- USGC CBOB Pasadena opened $3.5653/gal, closed $3.0005/gal (−15.8%); May average $3.4211/gal vs April $3.1830/gal (+7.5% MoM), the USGC grade firmer on average even as it sold off late.
- The crack ($/bbl) rose to a mid-month peak then eased; the weekly path diverged from flat price, so phases are tabled below.
- Crack peaked W20 (mid-May, daily high $42.84/bbl on 11 May) then gave back roughly $8/bbl into month-end; flat price fell every week, confirming the late-month softness was crude-led with gasoline margin holding most of its gain.
Cross-Commodity Dynamics
RBOB-Brent crack tripled and its volatility collapsed; the octane premium widened as summer blending bid for high-octane components.
- Crack averaged $37.17/bbl vs April $13.34/bbl (+179% MoM); April spanned −$7.89 to +$32.13/bbl (CV 113%) as the spring crack transition repriced from near-zero, while May held a $30.07 to $42.84/bbl band (CV 10.7%), a regime that settled rather than spiked.
- The compression of crack CV by roughly 10x is the analytical tell: hedging models calibrated to April's swing are oversized for May's range; the elevated crack is now the baseline, not an event.
- Premium-regular octane (CARBOB) widened within May from +$0.11/gal (open) to +$0.26/gal (close), May average +$0.276/gal; the widening into month-end is consistent with octane scarcity as summer-spec blending pulls high-octane components.
Market Activity
Buy-side tilt softened from 1.26 to 1.05 as coverage front-loaded into April's crack expansion.
- Bid/offer ratio 1.05 in May vs 1.26 in April.
- The easing toward balance fits consumer and blender coverage having been front-loaded into April, when the crack repriced from near-zero to the $30s; with the bid largely in place, May flow was more two-sided even as the crack held elevated.
- Completed-trade conversion stayed high (73% of transactions in May), consistent with an actively clearing market rather than a thinning one.
Cross-Market Dynamics
NYH barge basis to NYMEX flipped to a screen premium on the final session, an early East Coast prompt-tightness signal.
- RBOB NYH barge differential to NYMEX futures sat at a $0.05-0.065/gal discount through April and most of May (May average −$0.0425/gal), dipped to −$0.08/gal on 27 May, then flipped to +$0.065/gal on 29 May.
- A cash premium to screen is the standard read for East Coast prompt firmness or Colonial constraint; one print is not a trend, but the month-end flip is the first positive basis of the window and worth tracking against Colonial line space.
Cross-Regional Dynamics
West Coast premium over USGC compressed from +$0.67 to +$0.44/gal as Gulf gasoline firmed faster.
- CARBOB-CBOB spread averaged +$0.4405/gal in May vs +$0.6687/gal in April (−$0.228/gal MoM); within May it compressed from +$0.58/gal (open) to +$0.29/gal (close).
- The compression was USGC-led: CBOB averaged +7.5% MoM on driving-season and crack strength while CARBOB was flat-to-lower, shifting relative tightness toward the Gulf; the WC retains a structural premium but the gap is narrowing.
Something To Watch
- Crack sustainability against the new ~$37/bbl floor:
- Observation: RBOB-Brent crack settled into a $30-43/bbl May range, CV down to 10.7%
- Why it matters: the crack, not flat price, carries the gasoline barrel May-September; a sustained break below ~$30/bbl would signal driving-season demand disappointing, while a hold above $35/bbl confirms the margin regime.
- What to monitor: daily RBOB-Brent crack; EIA Wednesday product supplied (gasoline) and gasoline stocks vs 5-year (10:30 ET).
- NYH barge basis and Colonial as the East Coast prompt signal:
- Observation: NYH barge-to-screen flipped to +$0.065/gal on 29 May after a month at a discount.
- Why it matters: a sustained positive basis signals East Coast prompt tightness and an open Gulf-NYH arb; reversion to discount means the flip was noise.
- What to monitor: daily NYH barge differential; Colonial line space (positive cpg = arb open); PADD 1 gasoline days of supply.
- Hurricane season open (1 June) into peak driving demand:
- Observation: season opens with the crack already elevated and USGC the relative-tightness leg.
- Why it matters: Gulf refinery shut-ins drive RBOB cracks higher on lost supply; with margins already firm, the crack has less cushion before spiking.
- What to monitor: NOAA tropical outlooks for Gulf landfall (not cone-of-uncertainty); USGC CBOB basis; refinery utilisation in the EIA print.
- Octane spread as the summer-blending scarcity gauge:
- Observation: premium-regular CARBOB widened to +$0.26/gal at month-end.
- Why it matters: a widening octane premium signals tight high-octane component supply into peak blending; compression would signal the summer octane bid easing.
- What to monitor: weekly premium-regular CARBOB spread; alkylate and reformate availability proxies.
Note: All figures, prices and market activity referenced in this report are based on the period 1 to 29 May 2026.
.webp)
