Shengyishe published its September 8 sulfur benchmark at 8,201.75 yuan per tonne on Tuesday morning, a 437.25 yuan or 5.06 percent drop from the September 7 print of 8,639.00 yuan.
The national index is down 1.76 percent from the September 1 month-start level of 8,349 yuan, reversing most of the early-September bounce that had carried the benchmark 3.47 percent higher through September 7.
Shengyishe's daily change field put the session move at negative 5.06 percent, the largest one-day percentage decline in the early-September window.
The platform's trailing-year statistics show a minimum of 2,627.67 yuan, a maximum of 11,084.33 yuan, and a median of 6,856 yuan, placing the September 8 print in the mid-high band on a one-year horizon.
Shengyishe's September 8 technical read classified the structure as a deep correction with bearish oscillation, a reversal from the strong-consolidation signal published September 7.
The five-day average spread collapsed to negative 342.47 from 14.67, the ten-day spread turned negative at negative 17.05 from positive 6.33, and the twenty-day spread narrowed to negative 303.87 from negative 312.17.
That (-, -, +) combination is what Shengyishe labels deep correction oscillation, distinct from the (-, +, +) strong-consolidation read that held through September 7.
Position reference put the sixty-day and three-month cycles in the lower price band, implying limited further downside after the sharp session, while the one-year cycle remains mid-high with callback pressure from the June peak.
Port inventory at 965,700 tonnes on September 7 remains a supply-side weight even as the national benchmark corrects, a pairing PriceSeek flagged as bearish on September 7.
Longzhong's September 4 review had described early September firming as a bounce with autumn phosphate fertilizer stocking below expectations. Tuesday's drop tests whether that bounce has exhausted.
For the Vancouver stem, a national index that falls below 8,300 yuan would narrow the Pacific nomination window that opened when FOB quotes lagged domestic moves through August.
SMM's open H1 2026 account described Canada as a swing supplier with annualized export volume near 5.22 million tonnes, so Pacific loadings still correlate with Chinese import appetite even when Hormuz seaborne remains impaired.
Middle East seaborne through Hormuz stays impaired in open trade reporting, which keeps Chinese domestic refinery output and port stocks as the primary demand signal for Pacific nomination timing.
Desk read: September 8 confirms a sharp one-day correction in Shengyishe's national benchmark. Watch whether port granular prices follow the index lower or whether the sixty-day lower-band reference limits further downside.