Shengyishe's September 10 spread monitor put the ten-day minus twenty-day moving-average gap at negative 261.53 yuan per tonne.
The calculation uses M10 at 8,440.60 yuan minus M20 at 8,702.13 yuan, both derived from the platform's national sulfur index.
Shengyishe classified the session as a shift from negative expansion to negative shrinkage, indicating the pace of decline is slowing.
The platform labeled the combination a potential inflection signal, though it cautions that negative shrinkage alone does not confirm a trend reversal.
On September 9 the same monitor had put the gap at negative 302.88 yuan in negative expansion, signaling accelerating downward momentum after the early-September peak.
The 41.35 yuan narrowing in the spread gap coincided with the benchmark's 1.69 percent daily rebound to 8,264.25 yuan on the same session.
September 8's 5.06 percent one-day drop had been the largest single-session move in the correction, followed by a modest 0.91 percent decline on September 9.
Port inventory at 965,700 tonnes on September 7 in open Shengyishe data continues to weigh on spot even as the national index stabilizes.
SunSirs described a wait-and-see market on September 10, with geopolitical risk premiums anchoring import costs while downstream phosphate buyers limit acceptance of high-priced supplies.
For the Vancouver stem, technical inflection signals in the Chinese domestic index are secondary to Pacific netback math driven by Gulf FOB postings and freight.
Desk read: September 10 spread data supports a corrective pause, not a confirmed uptrend. Alberta export nominations still price on seaborne landed costs, not domestic Chinese technicals alone.