Say you benchmarked your polyethylene price when you renewed your two-year contract, about 14 months ago. You pushed hard and got a deeper discount off the index than before. Every invoice since then has followed the formula exactly, so nothing has given you a reason to re-benchmark resin pricing.
Meanwhile, the market kept moving. Not long after you signed, while producers were fighting for volume, a few buyers your size renewed and walked away with discounts a couple of cents deeper than yours. Your price slid from competitive to above market, and nothing on your invoices or in your contract showed it.
That slow slide, which we'd call drift, is how most benchmarks go stale. Because it never shows up as one big jump, waiting until your next renewal to check won't catch it until you've overpaid for months, but a simple rhythm will: a light check every month, a fuller review every quarter, and a deep one well before each renewal. A few market events should send you back early, too.
You did the work when you renewed, and your benchmark was right on the day you ran it. It went stale anyway, because the market, and sometimes your own business, kept moving while your contract stayed put.
A benchmark compares your net price with what buyers like you pay for the same grade, delivered the same way, and at similar volume. But producers keep each buyer's discount confidential, so you can't read that market number off your own contract. You have to estimate it from outside, using a second supplier's price, a fresh quote, or a resin price benchmarking service based on actual transactions.
That outside estimate won't add much on index moves, since a move in the published index reaches every buyer on that index for the same month, and your invoice and formula already show whether you were billed correctly. Instead, it catches your price drifting away from what other buyers pay while the index moves all of you alike.
Usually, that drift comes from the market shifting around a fixed deal. On a typical North American polyethylene contract bought direct, your price is set as a discount off a monthly index. When producers start offering bigger discounts to win business, the buyers who renew or switch suppliers lock in deeper discounts than yours, while yours stays right where you signed it.
Polypropylene drifts a little differently, because many PP contracts are priced as the monthly propylene contract price plus a margin. Where your contract fixes that margin for the term, accepting a bigger one than other buyers got at renewal costs you every month until the contract ends, and the propylene price won't show a thing.
Freight and packaging charges drift the same way, a little at a time, so no single month's change looks big enough to flag. Even your own growth can leave you overpaying. Unless your contract spells out its volume tiers, you usually have to ask for the lower price a higher tier should earn you. You'll only find any of this if you go looking.
So the question is how often to go looking. For most buyers, three layers of checks will catch drift. The monthly check stays on your highest-spend grades, while the quarterly and renewal reviews widen out to freight, terms, and the formula itself. If you've never benchmarked at all, a monthly check on your top two or three grades is the place to start, and a smaller buyer can simply keep it to those.
This is the check that would have caught those other buyers' deeper discounts within a month or two. Once a month, compare your net price on your highest-spend grades against an outside reference. Your own index won't work for this, because on an index-based contract you'd only be measuring your price against the formula it came from.
A fresh quote won't hold up monthly either, because suppliers you aren't buying from tend to stop sending serious ones when you ask that often. You'll get a steadier monthly read from benchmark pricing based on actual transactions, even if you buy through distributors, as long as it reflects distributor pricing on the same delivered basis and packaging rather than direct railcar prices. And if you buy from two suppliers, the other's price makes a useful cross-check, though both contracts can still sit above market at once.
Timing can throw the comparison off, too. Invoices are often billed provisionally and trued up once the month's index settles, sometimes a month or more later, so compare settled months only. Even then, a bad month may just be resin index lag, the delay while the monthly index catches up to spot, the open-market price. That lag hits every buyer on the same index alike, though, so we'd watch how far your net price sits from what comparable buyers pay that month, and if the distance grows two months running, it's time to look closer.
Since the monthly check only covers price on a few grades, every quarter we'd widen it to every grade you buy in meaningful volume, plus a fresh quote or two from suppliers you don't buy from, who'll take the request more seriously a few times a year than every month. Look past the price per pound, too, since freight, delivery mode, rebates, payment terms, and the premium you pay for packaged material all change what you actually pay.
A quarterly review is also a good time to give finance a fresh benchmark for the budget, because a cost forecast built on today's price carries any overpayment forward. Neither the monthly check nor the quarterly review changes your deal by itself, though. They give you the evidence to act on, whether that's mid-contract or at renewal.
Renewal is when you can actually change the deal, so it gets the deepest re-benchmark. Your contract sets a notice deadline for telling the supplier you want to renegotiate or exit, and it can fall well before the contract expires. If the contract has an evergreen or auto-renewal clause, meaning it renews on its own unless you give notice, missing that date can roll it over, sometimes for another full term. Our resin contract renewal playbook runs about 90 days, so count those days back from the notice deadline rather than the expiry date.
Before you negotiate, test the formula along with the price, starting with which index and month it references and whether your discount or margin still matches what similar buyers get. Then go through your clauses. Volume rebates should still fit what you buy, and if you have meet-or-release, meaning the supplier must match a competing offer or let you buy that volume elsewhere, its terms should still be workable. The same goes for any price cap, floor, or collar, which limit how far your price can rise, fall, or both.
That schedule is built for drift, which happens slowly. Some events, in the market or in your own business, move faster and can change where you stand within weeks, so when one hits, we'd check right away.
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Now say one of those checks, scheduled or not, shows you're above market mid-contract. A price is easiest to fix at renewal, but you've still got options before then, depending on the contract.
If you buy from two suppliers, we'd start by shifting volume toward the one closer to market, as long as your commitments, your customers' grade approvals, and your rebate tiers allow it. A meet-or-release clause can help too. To use one, you'll usually need a written offer from another producer on a comparable grade, volume, and term, and your supplier then gets time to verify it.
Even without that clause, you can ask your supplier to adjust your price, and some will rather than risk losing share at renewal. If none of that works right away, keep logging the numbers. Your monthly checks become a record of where you're overpaying going into renewal, which is when a live competing offer can fix it.
Of course, that record only exists if the checks keep happening, and when the monthly check means rebuilding your procurement benchmarking in a spreadsheet by hand, it tends to slip. ResinSmart gives procurement teams like yours market analytics that show how prices on your grades have moved, so you don't have to follow the market by hand. You need a benchmark to see where your own price sits against comparable buyers, though, so our higher-tier plans add resin pricing benchmarks informed by more than 3 billion pounds of transaction data, along with advisory support for renewals.
Start your free trial today and catch the market turns that should send you back to your benchmark.
Most buyers should check their top grades against an outside reference monthly, review every grade and cost term quarterly, and run an in-depth re-benchmark before each renewal. Increase letters, market turns, and supply disruptions should trigger an extra check.
A resin price benchmark goes stale because the market keeps moving after it's run while your contract stays fixed. Producers may offer deeper discounts to other buyers, and freight, packaging, and your own volume can shift.
Compare your net price against an outside reference each month, such as a transaction-based benchmark or a second supplier's price, and save fresh quotes for a quarterly review. On an index-based contract, comparing against your own index only measures your price against the formula it came from.
Start re-benchmarking before a resin contract renewal by counting back from the notice deadline, not the expiry date. Notice periods vary by contract, and missing one under an auto-renewal clause can roll the contract over, sometimes for another full term.
If a re-benchmark shows you're paying above market mid-contract, shift volume toward a second supplier where your commitments allow, use a qualifying offer to trigger a meet-or-release clause if you have one, or ask your supplier to adjust. If nothing changes, keep the record for renewal.
Smaller resin buyers can usually re-benchmark on the same schedule, just across fewer grades. Start with a monthly check on the two or three highest-spend grades.