Polyester Filament Desensitized to Crude Oil: A Pricing Power Shift Driven by Inventory Cycles

When Brent crude plunged 7.3% to $81.55 per barrel on the morning of August 3, the calmest group in the textile circle was surprisingly the buyers of polyester filament. Conventional logic suggests that crude oil, as the source of the polyester industry chain, should quickly transmit its price volatility to filament quotes. Yet in reality, filament prices only adjusted by 50-100 yuan per ton per day, and even remained nearly flat on the day of the oil crash. This 'desensitization' is not accidental, but the result of combined effects of inventory structures, capacity cycles, and demand expectations across the chain.

Event Background: Oil Price Rollercoaster vs. Filament's Cold Treatment

The oil price plunge on August 3 was directly triggered by Trump's policy reversal on Iran—from threatening to strike energy facilities to announcing imminent negotiations within 48 hours, causing drastic fluctuations in the financial market. WTI fell below $80 per barrel, down 6.25%, while Brent recorded one of its largest single-day drops in recent times. However, during the same window, mainstream polyester filament prices only edged down slightly, and some varieties held steady.

This divergence is not new. Since 2024, repeated US-Iran conflicts have caused oil prices to swing wildly, but polyester filament has maintained a rhythm of 'small steps up, basically no move down.' From an industry perspective, this reflects a declining sensitivity of the polyester segment to upstream costs—because the pricing power of filament has shifted from 'cost-push' to 'inventory and demand-driven.'

Industry Impact: Inventory Cycles Rewriting Pricing Logic

Behind filament's 'immunity' to oil lies a profound change in inventory patterns upstream and downstream. Currently in the traditional off-season, downstream weaving mills operate at less than 50% capacity, with most factories only making replenishment purchases, insensitive to minor price fluctuations. This means that even if oil crashes, without downstream buying, filament lacks demand support for price increases, and no one is willing to accept price drops, so prices naturally remain in a narrow range.

More critical changes are in grey fabric inventories. Data show that due to large-scale production cuts in the weaving sector in the first half of this year, average grey fabric inventories at factories had fallen by more than 10 days compared with the same period last year by the end of July. This destocking implies that once downstream demand picks up, the market may shift from a buyer's market to a seller's market—historically, grey fabric prices tend to rise when the expectation of inventory depletion appears, not when inventories are actually exhausted.

For polyester mills, this 'desensitization' is both a risk and an opportunity. The risk is that if oil continues to fall while filament prices remain high, downstream resistance may intensify, further compressing demand; the opportunity is that if demand starts in late August, low inventories will give filament stronger pricing power, potentially leading to an independent upward trend.

Practical Recommendations

For Purchasers - Short-term procurement strategies should downplay oil price fluctuations and focus on polyester mills' inventory days and maintenance schedules; when inventories are low, avoid chasing price spikes or selling off. - Recommend extending procurement cycles to more than half a month, using the current off-season price stalemate to lock in forward contracts, mitigating the risk of price increases when demand picks up in late August. - Monitor the destocking pace of grey fabrics; if it accelerates, prepare raw materials in advance to cope with potential price transmission.

For Foreign Trade Enterprises - When quoting export prices, do not use oil prices as the sole adjustment basis; instead, refer to the weekly polyester filament price index published by the China Chemical Fiber Industry Association, and set linkage clauses for exchange rate and raw material fluctuations. - When communicating with clients, emphasize that current filament prices are relatively stable, and try to extend order price lock-in periods from 30 to 60 days to reduce price uncertainty for both sides. - Pay attention to the impact of the Strait of Hormuz blockade on oil transportation costs; although the short-term impact on filament prices is limited, if the situation escalates, it may push up PX import costs, so assess supply chain risks in advance.