Buy side · what advertisers pay
Programmatic CPM
By Oliver Wakefield-Smith · updated July 2026
Benchmarks reviewed July 2026 · next review October 2026
The short answer
Open-exchange display clears one impression at a time in real-time auctions; no authority publishes a single current average, and this site does not either. What IS sourced, and matters more: the UK CMA's market study found adtech intermediaries capture around 35% of advertiser spend in the open-display chain. Your CPM is not the publisher's CPM.
The bid you pay vs the CPM the publisher receives
Between your DSP bid and the publisher's statement sit the DSP fee, the exchange take, the SSP fee, verification vendors and data costs. Apply the CMA's ~35% finding to a worked dollar:
publisher receipt ≈ advertiser CPM × (1 − intermediary take)
$4.00 advertiser CPM × (1 − 0.35) ≈ $2.60 to the publisher
$10.00 advertiser CPM × (1 − 0.35) ≈ $6.50 to the publisher
Take rate: CMA market study finding (~35%), applied to illustrative CPMs. Individual chains vary; the CMA also flagged spend it could not attribute at all.
This is why buyer-side CPM and seller-side eCPM never reconcile on the same impression: they are separated by the whole supply chain. The metric-level version of that divergence is worked at CPM vs eCPM, and the litigation record (the DOJ's adtech monopolization suit) is the running documentation of who charges what in the middle.
Why open-exchange CPMs run low
Infinite long-tail supply, degraded targeting signal since third-party-cookie deprecation began, and adverse selection: premium publishers push their best inventory into direct and PMP deals, so the open exchange concentrates what nobody reserved. A cheap open-exchange thousand is cheap for reasons.
Open exchange vs PMP vs programmatic guaranteed
- Open exchange: everyone bids, lowest friction, full fee chain, least inventory control.
- PMP: invitation-only auctions on curated inventory; floors higher, chain shorter.
- Programmatic guaranteed: fixed CPM, reserved volume; closest digital cousin of the old insertion order.
Related lanes: Google Display, Amazon DSP, and the publisher's side of this chain at eCPM. Full table: /rates.