Shengyishe's September 11 trend analysis put the five-day average spread at negative 14.95 yuan per tonne, the ten-day spread at negative 136.40 yuan, and the twenty-day spread at negative 261.53 yuan.
Compared with the prior session, the five-day gap improved from negative 109.90, the ten-day gap deteriorated from negative 72.42, and the twenty-day gap narrowed from negative 302.88.
The resulting (+, -, +) combination is classified as a stagnation warning with bearish tilt, distinct from September 10's negative-shrinkage inflection signal.
Shengyishe concluded the national sulfur index is oscillating because the three spread changes do not align for a clear directional call.
Position reference put sixty-day and three-month cycles in the lower price band, implying limited near-term downside after the September correction.
The one-year cycle remains in the mid-high band, implying limited upside from current levels after the June peak above 11,000 yuan.
September 10's benchmark rebound of 1.69 percent to 8,264.25 yuan had coincided with a narrowing of the ten-day minus twenty-day gap that Shengyishe labeled a potential inflection.
September 11's stagnation warning interrupts that inflection narrative without confirming a new downtrend, consistent with the benchmark's modest 0.30 percent daily gain to 8,289.25 yuan.
SMM's same-day account described upstream sulfur stabilizing while sulphuric acid weakened, a divergence that fits a market stuck between cost support and weak acid demand.
Port inventory at 966,200 tonnes on September 10 in open Shengyishe data continues to weigh on spot even as the national index stabilizes.
For Vancouver FOB netbacks, a Chinese market stuck in oscillation with a bearish tilt means Pacific buyers are not rushing to restock but are not walking away either.
Desk read: technical monitors are sending mixed signals after the early-September peak. Alberta tonnes on the Vancouver stem benefit from a buyer base that still needs sulfur even when Chinese spot hesitates.