Key takeaways
- A price index is an assessment — a price reporting agency's estimate of where deals could clear on a defined grade, location, Incoterm basis, and time window — not a record of any single transaction you can point to.
- The delivery basis is load-bearing: a CFR Far East Asia number already contains freight to the discharge port, an FD (free delivered) Northwest Europe number includes inland trucking, and an FOB number is at the loading port — never compare two indices without normalising them to the same basis.
- Most agencies publish a low–high range and a midpoint; the spread reflects assessed deal scatter and uncertainty, so a contract that settles on the mid is structurally fairer than one anchored to the high.
- Contract (monthly/quarterly settlement) and spot (this week's clearing level) assessments move differently — spot leads turning markets — so writing 'index flat' without specifying which series, which publication date, and which basis is how buyers quietly overpay.
A polymer price index is not a price you can buy at. It is an assessment — a price reporting agency's estimate of where deals for a defined grade could clear, on a specific delivery basis, in a specific region, over a specific time window. ICIS, S&P Global Platts (now part of S&P Global Commodity Insights), Argus, ChemOrbis and others run reporters who survey producers, converters, traders and brokers daily or weekly, filter the bids, offers and confirmed deals, and publish a number. That number is editorial judgement disciplined by methodology — closer to a surveyed estimate than to an exchange tick. Treat it as a reference point, never as an invoice.
The buyers who overpay are rarely the ones who ignore indices. They are the ones who anchor to an index without reading what is baked into it — the geography, the Incoterm, the contract-versus-spot distinction, and which part of the published range they are settling on. Each of those four choices can move the effective price materially per tonne. Get them explicit in the contract and the index works for you; leave them vague and the supplier's interpretation wins every month.
A reporting agency does not average a database of invoices. It defines a specification — say, blow-moulding HDPE of a stated melt flow and density range, in 25 kg bags or FIBC, on a CFR basis to a named port — and then assesses where that specification is trading. Reporters weigh confirmed transactions most heavily, then firm bids and offers, then talk. They normalise odd deals (unusual volumes, off-spec material, distressed cargoes, barter or countertrade) so a single fire-sale lot does not drag the print. The output is typically a low, a high, and a midpoint, plus a change-on-period figure.
The methodology matters because it tells you what the number excludes. A standard assessment usually assumes a benchmark volume (often a full container or a defined tonnage), standard packaging, prime (not wide-spec or recycled) material, and normal payment terms. Your actual deal may differ on every one of those — which is exactly why contracts are written as index plus or minus a differential, not as the bare index. The differential is where your grade premium, packaging, credit terms and freight quirks live. The same logic governs how a Certificate of Analysis and a quote should be read together: the headline number means little until you know the spec behind it.
An index tells you the temperature of the market. It does not tell you the price of your cargo — that is the index plus a differential you negotiate, not a number you inherit.
The single most expensive misread is comparing two indices on different delivery bases. The same tonne of polymer carries different headline numbers depending on the Incoterm the assessment is built on. FOB is at the loading port — before sea freight and marine insurance. CFR adds cost and freight to a named discharge port. CIF adds insurance on top. FD (free delivered) goes further, including inland haulage to the buyer's region, and is common in European resin assessments. The gap between an FOB Middle East Gulf number and a CFR Far East Asia number for the same grade is, in effect, the freight and insurance leg — and in a tight container market that leg is not small.
| Basis | Incoterm meaning | Costs included in the print | Typical use |
|---|---|---|---|
| FOB origin | Free On Board, loading port | Ex-works + port handling + loading | Comparing producer netbacks; origin arbitrage |
| CFR destination | Cost & Freight, discharge port | FOB + ocean freight to named port | Most Asian import benchmarks (e.g. CFR Far East / Southeast Asia) |
| CIF destination | Cost, Insurance & Freight | CFR + marine cargo insurance | Where insurance is bundled into the reference |
| FD region | Free Delivered to buyer's area | Landed cost + inland transport to region | European domestic assessments (e.g. FD NWE) |
| Delivered, domestic | Delivered local market | Full landed + local distribution | Domestic contract markets (US railcar, EU FD) |
Before reconciling any two quotes, normalise them to one basis. If a supplier quotes you CFR your port and a competing index publishes FOB origin, you cannot compare them until you add a realistic freight estimate. Our Incoterms 2020 guide for polymer buyers breaks down exactly where risk and cost transfer on each term, and our global polymer trade routes overview gives a feel for the freight legs that sit between FOB and CFR.
Most major resin markets carry both a contract assessment and a spot assessment, and they do not move in lockstep. Contract prices reflect the monthly or quarterly settlement negotiated between large producers and high-volume converters; they tend to move in steps and are often anchored to a feedstock contract reference such as the monthly ethylene or propylene contract price. Spot prices reflect where individual cargoes are clearing this week, and they react fast to feedstock swings, cracker outages, freight spikes and inventory builds.
The behavioural rule of thumb: spot leads contract in turning markets. When feedstock surges or a cracker turnaround tightens supply, spot moves first and contract follows the next settlement. When demand softens, spot falls ahead of contract. A buyer on a spot-linked formula feels both the upside and the downside sooner. Which clock you tie your contract to is a risk decision, not just a price decision — and it should be conscious. The link between feedstock and resin pricing is unpacked in naphtha vs ethane feedstock and in how polymer pricing works.
| Dimension | Contract assessment | Spot assessment |
|---|---|---|
| Settlement period | Monthly or quarterly | Weekly or daily |
| Counterparties | Producers ↔ large converters | Traders, distributors, opportunistic buyers |
| Volatility | Lower; moves in steps | Higher; reacts to feedstock & freight |
| Typical anchor | Monomer contract price + delta | Live cargo bids/offers |
| Leads or lags | Lags in turning markets | Leads in turning markets |
| Best for | Steady high-volume offtake | Topping up, arbitrage, spot demand |
The published range is information, not decoration. The low and high mark the assessed band of credible deals; a wide spread signals a thin, volatile or fragmenting market, while a tight spread signals consensus. The midpoint is the agency's central estimate and the most defensible neutral anchor for a contract — settling on the high systematically favours the seller, settling on the low favours the buyer, and neither survives a renewal negotiation cleanly.
To use an index in a contract without quietly overpaying, make every variable explicit. Vague language like 'priced at index, flat' is an invitation to be quoted the high print of the most expensive series on the supplier's preferred basis.
- Name the exact series: publication (e.g. ICIS or Platts), grade specification, region, and delivery basis (e.g. 'CFR Southeast Asia') — not just 'the HDPE index'.
- Pick the statistic: low, mid, or a stated percentile. Default to mid unless you have leverage; never accept an unstated 'index' that resolves to the high.
- Define the window: settle on the simple average of all weekly prints across the delivery month, not a single cherry-picked publication date. This neutralises timing games.
- Separate the differential: write price = index ± a stated currency/tonne differential for your grade, packaging and freight, so the premium is visible and negotiable each renewal.
- Fix the FX and timing: state the currency, the conversion source if any, and the exact publication used (and a fallback if that issue is skipped or the series is discontinued).
- Add a sanity clause: the right to re-baseline if the agency changes methodology or the assessed spread blows out beyond a defined threshold.
Indices are a discipline, not a crutch. The number on the screen is a surveyed estimate on someone else's chosen basis; your job is to pin down which series, which basis, which statistic and which window before you sign, then negotiate the differential in daylight. Buyers who do that turn the index into a shared, auditable reference — and stop paying the quiet premium that lives in the word 'flat'. For the broader market picture these assessments feed into, see polymer market data 2026, and when you are ready to benchmark a live requirement against current index levels, the OmniaStrata desk can map a quote back to its true basis.
Frequently asked
Questions on the desk
What is the difference between a contract price index and a spot price index?
A contract assessment reflects the negotiated settlement for a delivery period — typically a calendar month or quarter — agreed between large producers and converters, and it tends to move in steps. A spot assessment reflects where discrete cargoes are clearing right now, often weekly or daily, and it reacts faster to feedstock and freight swings. In a rising market spot usually leads contract upward; in a falling market spot leads it down. Always confirm which series a supplier is quoting before you accept 'at index'.
What do CFR, FOB, and FD mean on a polymer price assessment?
They are the Incoterm/delivery basis the price is built on. FOB is at the loading port (free on board, before sea freight). CFR includes cost and freight to a named discharge port. FD, or free delivered, includes inland transport to the buyer's region — common in European resin assessments. The same tonne of HDPE can carry three different headline numbers purely because of basis, so see our [Incoterms 2020 guide for polymer buyers](/blog/incoterms-2020-for-polymer-buyers) before reconciling quotes.
Why does an index show a low, a high, and a mid price?
Price reporting agencies survey many deals, bids, and offers across a market that is never a single cleared price. The low and high mark the assessed range of credible transactions for that grade and basis; the mid is the agency's best central estimate. A wide spread signals a thin or volatile market. Anchoring a contract to the mid — rather than the high — is the most defensible neutral reference for both sides.
How do I use a published index in a supply contract without overpaying?
Name the series precisely: the exact grade, the delivery basis (e.g. CFR Far East Asia), the publication, the frequency, and whether you use the low, mid, or a specified percentile. Settle on the midpoint of a defined window — for example the simple average of the weekly assessments across the delivery month — rather than a single cherry-picked print. Add a differential (plus or minus) for your grade and freight rather than letting the supplier embed an opaque premium. See [how polymer pricing works](/blog/how-polymer-pricing-works) for the full mechanics.
Are ICIS or Platts prices the actual prices producers charge?
No. They are independent assessments — informed estimates of market level — not a producer's invoice or a binding offer. Actual transaction prices vary by volume, credit terms, grade, packaging, and relationship. The index is a neutral reference point both sides agree to anchor against; the real price is the index plus or minus a negotiated differential.
General market commentary from the OmniaStrata desk, provided for information only. It is not legal, financial, tax, or trading advice, and it is not an offer or a commitment to any terms. Figures such as price ranges, spreads, financing costs, and credit periods are illustrative market context, not OmniaStrata's rates or terms. Actual contract terms — including price, payment instrument, credit, insurance, and Incoterms — are agreed in writing on a per-transaction basis and at OmniaStrata's discretion. Market conditions change; figures reflect the publication date.