When Brent crude climbed back above $100 per barrel, the substitution relationship between cotton and polyester was repriced once again. On September 9, the ICE December cotton contract settled at 87.28 cents per pound, up 0.96 cents or 1.11% in a single session, recovering from a three-week low of 85.56 cents. On the surface, this was a short-term lift driven by oil and a softer dollar. In substance, it reveals the core support logic for cotton prices today: not a demand surge, but a passive parity repair after the cost of substitute fibers rose.
Parity Logic: How Oil Transmits to Cotton
Polyester fiber derives its core feedstock from the petrochemical chain. Each step up in crude prices pushes the cost center of polyester staple fiber and chips higher. When oil breaks $100 per barrel, textile mills become more willing to accept cotton in their fiber blending, particularly in yarn categories where the blend ratio is flexible. This substitution elasticity shows up most directly in blended yarns.
At the same time, the dollar index hovering near two-week lows effectively lowers the cost of dollar-denominated commodities for overseas buyers. For spinning mills in Southeast and South Asia, the purchasing window becomes more attractive amid this currency swing. This means the near-term support for cotton comes not from a recovery in end-market apparel orders, but from a dual transmission through costs and exchange rates.
Supply Side: Falling Crop Ratings vs. Brazilian Abundance
The USDA's weekly crop progress report showed that as of September 6, the U.S. cotton good-to-excellent rating fell to 34%, down from 39% the prior week and 54% a year earlier. The harvest rate stood at 7%, unchanged year-on-year and slightly above the five-year average of 6%. The consecutive decline in crop ratings signals uncertainty over new-crop quality in the Northern Hemisphere, underpinning premium expectations for high-grade cotton.
But the Southern Hemisphere sends an opposite signal. Consultancy Agroconsult raised its 2025/26 Brazilian cotton production estimate by about 300,000 tonnes to a record 4.5 million tonnes, citing improved yields from field surveys. The significance of this increment lies in the marginal loosening of global supply forming in South America. The offset between expected U.S. crop losses and Brazilian abundance means cotton prices lack a fundamental basis for a one-way breakout.
Inventory data is equally calm. ICE reported that deliverable No. 2 cotton contract stocks stood at 54,414 bales as of September 8, unchanged from the previous session. The absence of visible destocking suggests the current rebound is driven more by capital flows and sentiment than by physical tightness.
Report Window: The Market Awaits Direction
Traders' attention has shifted to the USDA's upcoming World Agricultural Supply and Demand Estimates report. This report will provide the latest balance sheet for U.S. and global cotton supply and demand. The market needs it to gauge how much of the Northern Hemisphere harvest will materialize and whether recent price weakness has fully priced in bearish factors.
Before the report lands, the tug-of-war between support and resistance levels will persist. The Cotlook A Index stood at 96.10 cents per pound on September 9, up 10 points. The limited spot-market follow-through suggests physical traders remain cautious about confirming the futures rebound. For textile enterprises, what matters more than daily futures moves is the direction of the cotton-polyester spread over the coming quarter, as the oil price center shifts higher.