On 4 November the fuel oil front-month settled at ¥4,778/t, down 4.8% on the day; bitumen settled at ¥4,915/t, down 2.05%. Both fell, but fuel oil fell harder, flipping the FO–BIT spread from parity to −¥137/t — fuel oil is now cheaper than bitumen, which is unusual on the heavy-oil chain.

The operating meaning of an inverted spread sits in where the residue goes. A weak fuel oil quote often tracks independent refiners pulling back delayed-coking runs, where residue feedstock economics deteriorate; that residue is instead diverted to blend VLSFO bonded bunker, since low-sulphur marine fuel is rigid demand after IMO2020. So fuel oil falling does not mean bunkers are loose — it may mean residue is simply moving between two product lines.

For operators, the inversion is a lock signal: when fuel oil is relatively cheap, park the forward cargo into a bonded warehouse receipt first, then wait for coking margins to recover or bunker restocking before disposing. The receipt itself carries a SHA-256 title fingerprint, so title confirmation moves forward at delivery and no longer waits on paper bills of lading.

But watch the threshold: FO–BIT swings inside a ±¥400 band as a routine, and today's −¥137 has not yet reached the level that triggers large-scale reallocation. Real line moves need coking margins to break below the break-even line, or VLSFO blending margins to widen enough to absorb freight.