On the rubber line today, butadiene rubber (BR) rose 1.87% while natural rubber (NR) rose only 0.53% — on the surface BR is the stronger leg. But at CNY 14,965/t BR is still CNY 3,885/t below NR at CNY 18,850/t, so this is "relatively strong off a weaker base," not genuinely expensive. The root is butadiene. Several units are in turnaround, merchant volumes are down, and the BR cost side is pushed up. Tire makers run a blend ratio: when natural rubber gets pricey they blend in more butadiene, and when butadiene tightens the swing reverses. BR strength now means the blend scale is tipping toward butadiene, but the absolute gap is not wide enough for BR to fully substitute. For SNSUC's rubber transshipment the read is structural. Southeast-Asian NR arrival timing and domestic BR ex-works must be tracked separately, and cargoes are allocated to whichever side is cheaper. We do not bet one direction; we schedule ships on the delivered, duty-paid spread.