Shengyishe published its September 13 sulfur commodity index at 458.29 on Sunday, unchanged from the September 12 print.
September 13 sample prices ranged from 2,100 to 9,700 yuan per tonne with an average quote of 8,352.33 yuan, also flat from September 12.
The index remains 24.65 percent below the cycle peak of 608.19 reached on June 15, 2026.
It sits well above the February 24, 2020 trough at 25.79, when the same index series bottomed during the early pandemic demand shock.
The flat print follows a 15.74-point drop on September 12 from 474.03 and interrupts two sessions of modest recovery from the September 3 low at 472.01.
September 11 carried a stagnation warning on Shengyishe's spread monitor, classifying the market as oscillating with a bearish tilt after the early-September peak at 8,639 yuan.
SMM's September 11 weekly review described upstream sulfur stabilizing in Shandong even as sulphuric acid weakened, a divergence that fits a correcting rather than collapsing domestic market.
Middle East shipping risk through Hormuz and Bab el-Mandeb continues to floor import-cost math even as domestic Chinese indices pause their decline.
SMM put CIF Indonesia sulphur at 1,000 to 1,050 dollars in the September 11 week, the first softening in the Indonesian import band after months of stalemate.
Port inventory near 966,200 tonnes in open Shengyishe data from September 10 continues to weigh on spot even as the national index stabilizes.
For Alberta recovered sulfur on the Vancouver stem, a flat Chinese index does not remove Pacific demand but it signals buyers are not chasing offers higher.
Canadian export volumes through Vancouver rose in 2025 and early 2026 on inventory draws and supportive FOB margins while Gulf seaborne stayed impaired.
Desk read: September 13 is a pause print. The corridor read is unchanged: Alberta tonnes still compete into a Pacific market that needs sulfur even when Chinese indices stop falling.