Key takeaways
- The price of every commodity polymer is built from three layers.
- Here is what moves each one and how the layers compress when markets tighten.
When a buyer asks why polyethylene moved up forty dollars last week, the answer is almost never "resin demand." It is one of three upstream layers, and the layer that moved tells you whether the move will hold or whether it will reverse inside a month.
Most of the world’s polyethylene and polypropylene starts from naphtha cracking or, in North America and the Middle East, from ethane and propane cracking. Naphtha is a refinery cut, so its price tracks crude oil with a refinery margin layered on. Ethane is a natural-gas cut, so its price tracks the Henry Hub gas market.
When crude rises and gas does not, the spread between naphtha-based polyethylene (Asia, Europe) and ethane-based polyethylene (US Gulf Coast, GCC) widens. That is why North American producers usually undercut Asian producers in cost terms, and why the export volumes from those origins move opposite to the spread.
Cracking produces ethylene and propylene. Those monomers are themselves traded commodities, with their own price benchmarks (Asian Contract Price for ethylene, MOPJ for naphtha-derived monomers, Mt Belvieu for US ethane-derived). When monomer is short — because a major cracker is in turnaround — monomer prices rise faster than feedstock, and downstream resin follows three to six weeks later.
Resin is the layer the buyer actually transacts in. Resin price is monomer plus a polymerisation margin (the resin spread). When demand is strong the spread widens; when producers are competing for orders it narrows. In commodity polyethylene the spread typically runs $80–$200 per tonne. In specialty grades it can be five times that.
If feedstock is stable and monomer is stable but resin is moving, the move is demand-driven and likely to last several quarters. If feedstock is moving but monomer is stable, the change has not yet been passed through and a price step is coming. If monomer is moving but feedstock is not, somebody upstream is in turnaround and the move will partly reverse when the unit restarts.
OmniaStrata’s pricing intelligence pulls all three layers daily. We do not publish a daily price index — the public ones (ICIS, Platts, Argus) cover that better than we could — but we use them in every active negotiation to tell a buyer why an offer moved, which is more useful than telling them how much it moved.
Pricing also interacts with origin geography. The GCC region’s ethane advantage is a structural cost feature, not a market one — it is why Saudi and Qatari volumes anchor the global polyethylene cost curve.