Method · version 0.2 · published before the first number

How the spreads are derived, and what they cannot tell you.

XV-SAF-BASIS does not assess the price of SAF. Platts, Fastmarkets, BNEF and EASA already publish that. It publishes the relationships between those published numbers: the spread between the traded price and the cost of making the fuel, between SAF and the jet it replaces, between one delivery basis and another, and between regions. Those spreads are what an airline, a lender or a producing refinery actually negotiates over, and no single publisher reconciles them.

Spread definitions

Spread	Leg A	Leg B	Definition
tradedOverCost	safCifNwe	safCostNl	What the market pays for delivered HEFA SAF minus the published base production cost of making it. The margin available to a producer before logistics, blending, certification and intermediation.
safOverJet	safCifNwe	jetCifNwe	The green premium in its simplest form: the same basis, the same assessor, the same day, two molecules.
cifOverFob	safCifNwe	safFobAra	What delivery into Northwest Europe adds over loading at ARA-Ghent. Freight, insurance and the small basis premium for delivered product.
europeOverAsia	safFobAra	safFobSingapore	The regional arbitrage that would justify moving molecules, before freight. Negative spreads mean the market is not clearing on transport economics.
californiaOverEurope	safCalifornia	safFobAra	What policy design is worth per tonne. California's incentive stack against the European mandate.

Qualification test

An observation enters the index only if it carries all six of the following. Missing any one, the spread is withheld rather than filled.

1  assessor        a named publisher, not an anonymous market source
2  value           a number, not a range expressed as a midpoint by us
3  unit            USD or EUR per metric tonne
4  basis           CIF NWE, FOB ARA-Ghent, FOB Singapore, California, ex-works
5  observed date   the date the assessor assessed, not the date we read it
6  url             a public address where the number can be checked

Unit discipline

A spread is computed only between legs carrying the same unit. The EASA reference is published in EUR per tonne and is listed but not used in any spread, because converting it would introduce an exchange-rate assumption we would then have to defend. It is shown; it is not combined.

Mixed dates

Where the two legs carry different observation dates the spread is computed and published with the mixed_dates flag, and both dates are shown on the row. The spread is not smoothed, not annualised and not restated to a common date.

Publication rule

cadence   Weekly, Wednesday, 17:00 London

rule      A spread is published only when both inputs are published observations carrying an assessor, a date and a basis. No input is estimated. Where the two inputs carry different dates the spread is published with the mixed_dates flag and both dates shown.

revision  A published spread is never overwritten. A correction is issued as a new record carrying the original, the corrected value and the reason.

What this does not include

We do not run a pricing panel, take bids or offers, or assess what traded.
We do not estimate a price for any market where no assessor has published.
We do not convert currencies. EUR-denominated references are listed and excluded from spreads.
We do not net out EU ETS support, UK buy-out value or any regulatory transfer. Those change what a buyer pays, not what the fuel costs.
We do not adjust for freight, quality, volume or term. A published basis is taken as published.
We do not claim any spread is achievable. A spread between two assessments is not a trade, and it is not a margin any specific company earned.

The widest error this index can make is treating two assessments of different things as two assessments of the same thing. The basis field exists to make that visible rather than to hide it.

Known limitations, stated plainly

Five observations do not make a series. This is a first publication. It establishes the method and the arithmetic. A spread is only informative once it has been published weekly for several quarters, because the change in the spread is the signal and the level is not.

We are downstream of the assessors. If Platts revises a price, our spread changes. We publish the revision as a new record rather than overwriting, so the history shows who moved first.

Freight is inside the CIF–FOB spread. That spread is not pure basis premium. It contains freight, insurance, and whatever the delivered market will bear. We do not decompose it, because no publisher gives us the legs.