The most telling move today is the split inside the complex. Fuel oil at 4,986 rose 0.59% and bitumen at 4,488 rose 0.85% — both heavy-oil lines firming. Natural rubber held near 19,865, while butadiene rubber dropped 1.78% to 15,720. Within one chemical board, the heavy-oil leg and the synthetic-rubber leg went their own ways.

The cause sits at the feedstock level. Fuel oil and bitumen track the heavy cut of crude, so today's crude gains passed straight through. Butadiene rubber is built on butadiene, a by-product of ethylene cracking, which does not move with crude. Domestic unit run rates have recovered lately, and the moment supply loosened, price gave way.

For SNSUC's 13-category pricing sheet, one curve cannot cover everything. The heavy-oil family uses delivered crude cost plus the crack spread; the rubber family needs a separate read on butadiene units and downstream tire operating rates. Today we pulled butadiene rubber's quote weight out of the crude-linked formula and gave it its own butadiene factor, so the listed price stops drifting off the real driver.