The biggest mover today was not crude but fuel oil. At ¥5,349/t it rose 6.38% on the day, leaving bitumen (+3.61%) behind and pushing the FO-BIT spread to ¥583/t. That size of move is unusual inside the residue chain and points to two forces.

One is the delayed-coker feed switch. As fuel oil runs richer than bitumen, independents weigh residue allocation between coking and bunker blending—a wider FO-BIT spread argues for sending residue to the coker for gasoline and diesel rather than to marine fuel. The counterforce is winter VLSFO bonded-bunker stocking, which pulls low-sulfur residue out toward Zhoushan bunkering demand ahead of season.

The two forces fight, and fuel oil gets bid up one-sidedly. For SNSUC's bonded receipts, the amplified volatility tests pledge liquidity—a T+0 receipt pledge compresses the 50,000-tonne working-capital cycle from T+3 to same day, cutting the capital tie-up by nearly a third.

Operationally, first check whether this fuel-oil run is panic bidding. If coking margins are genuinely repairing, the spread holds in the ¥400–600 band; if it is bunker panic, the move is shorter. Lock receipts on dips, not on the spike.