Crude fell 7% and the heavy end did not escape. Fuel oil's front month settled at 5,050 yuan/t, down 5.38%, and bitumen at 4,989 yuan/t, down 5.44%. The two fell almost in lockstep, which tells you this was a broad cost-side repricing, not a standalone move in one grade.

The FO-Bit spread compressed to 61 yuan/t. Normally one leg follows bonded-bunker demand and the other follows road-construction and waterproofing demand, so the spread can widen. Today both fell together and the spread actually narrowed, forcing independent refiners to re-slice residual between coking units and bonded bunker blending.

Which way the residual flows depends on where the marginal return is higher. Cheaper crude lowers the cost of coker gasoline and diesel, making the coking route attractive; but bonded bunker restocking demand persists and blending components still find a home. Refiners steer residual by the spot crack each day, with no fixed ratio.

For trading desks, the heavy-end signal today is that the crack did not strengthen on its own. Crude fell and products fell with it, so refiner margins were not automatically opened; if anything they stayed under pressure because products tracked crude down. A real margin bounce needs products to lag crude, and that only shows up over the next few sessions.