Shengyishe published its September 15 sulfur benchmark at 7,869.00 yuan per tonne on Tuesday morning, down 483.33 yuan or 5.79 percent from the September 14 print of 8,352.33 yuan.
The benchmark is down 5.75 percent from the September 1 level of 8,349.00 yuan in open Shengyishe statistics.
The platform's September 15 trend analysis classified the market as clearly declining, with five-day, ten-day, and twenty-day spreads all negative and moving in the same direction from the prior session.
The five-day spread widened to negative 431.43 yuan per tonne from negative 27.15 yuan on September 14, while the ten-day spread moved to negative 36.86 yuan from negative 34.81 yuan.
The twenty-day spread deepened to negative 183.36 yuan per tonne from negative 171.36 yuan on September 14.
Shengyishe said the structure met its rules for a clearly declining signal because all three spreads were negative and each moved further negative from the prior day.
The benchmark sits in the middle-high band of its one-year range, with a one-year minimum at 2,627.67 yuan and maximum at 11,084.33 yuan.
The correction ends three sessions of flat sample averages near 8,352 yuan through September 14, when the platform had classified the market as strong consolidation with a bullish tilt.
Middle East shipping risk through Hormuz and Bab el-Mandeb continues to floor import-cost math even as the domestic Chinese benchmark corrects.
SMM's prior weekly reviews described upstream sulfur stabilizing in Shandong while sulphuric acid weakened, a divergence that fits a correcting rather than collapsing domestic market.
Port inventory near 966,200 tonnes in open Shengyishe data from September 10 continues to weigh on spot even as the national benchmark moves lower.
For Alberta recovered sulfur on the Vancouver stem, a lower Chinese benchmark signals buyers are not chasing offers higher even as Pacific demand remains structurally tight.
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 15 is the largest one-day percentage move in the early-September window after three flat sessions. The corridor read is unchanged: Alberta tonnes still compete into a Pacific market that needs sulfur even when Chinese benchmarks fall.