Strategy
Part of Private marketplace auctions in UK programmatic buying
Private marketplace auctions in UK programmatic buying
How a private marketplace auction works in UK programmatic buying, how it compares with open and direct deals, and what buyers should check before signing.
What to take away
- A private marketplace deal is an invitation-only auction for inventory from named publishers, usually with a floor price agreed in advance.
- PMP deals sit between the open marketplace and programmatic direct, so compare all three on the same outcome metric.
- Ask for the publisher list, the floor logic, the full fee stack and the measurement rules before you commit budget.
- Run the deal alongside open marketplace buying for a fixed period so the difference shows up in your own data.
- A PMP changes the route to inventory, not the consent basis; check the consent and data arrangements before launch.
Where a PMP sits between open market and direct
A PMP is an invitation-only auction. Publishers or their sales houses release defined inventory to a chosen group of buyers, who bid inside that contained auction. The floor price, the publisher list and the deal ID are agreed in advance.
Deal types compared
Open marketplace
- How bought
- Open auction
- Pricing
- Clearing price
- Transparency
- Limited
- Best for
- Reach
Private marketplace
- How bought
- Invitation-only auction
- Pricing
- Agreed floor
- Transparency
- Named publishers
- Best for
- Controlled reach
Programmatic direct
- How bought
- Fixed deal
- Pricing
- Negotiated fixed
- Transparency
- Full contract
- Best for
- Guaranteed volume
In the UK, that inventory often arrives through a sales house representing several media owners. One negotiation then covers titles with different audiences, different data rules and different editorial standards.
On the buy side, DSP examples include Google Display & Video 360 (DV360), The Trade Desk and Amazon DSP; SSP and exchange examples include Magnite, PubMatic and Index Exchange. UK media owners to ask about include Guardian News & Media, News UK and Immediate Media; this does not imply that each offers every title through a PMP. If you use an agency, ask its programmatic team, for example at WPP or Omnicom Media Group, who controls the buying seat and has access to the deal.
The open marketplace works the other way. Any buyer can bid on any impression, which brings reach but also unknown placements, weaker curation and more exposure to low-quality inventory.
Programmatic direct removes the auction. You agree a fixed price and a guaranteed volume with one publisher, then deliver against that commitment.
Where a PMP sits
How inventory is bought
- Open marketplace
- Open auction on an exchange
- Private marketplace
- Invitation-only auction
- Programmatic direct
- Fixed deal, no auction
Pricing
- Open marketplace
- Clearing price set per impression
- Private marketplace
- Agreed floor, bids above it
- Programmatic direct
- Negotiated fixed price
Transparency
- Open marketplace
- Limited, domain lists vary
- Private marketplace
- Named publisher list, deal ID
- Programmatic direct
- Full, contract level
Best suited to
- Open marketplace
- Reach and cheap incremental volume
- Private marketplace
- Controlled reach on trusted titles
- Programmatic direct
- Guaranteed volume on premium placements
A five-step check before you sign
- Map the inventory. Ask which domains, apps and placements sit inside the deal, and whether video, display or audio is included.
- Benchmark the floor. In your DSP's reporting, compare the PMP floor with open-market clearing prices for the same domains over 30 days; check that the report uses comparable formats and placements.
- Read the fee stack. Separate the publisher floor, the supply-side fee, the demand-side fee and any data fee, because the headline price is not what you pay.
- Fix the measurement. Agree viewability, brand safety and outcome metrics in writing, and decide who pays for verification. Compare providers such as Integral Ad Science (IAS) and DoubleVerify, and check that the selected service works with your DSP. For a shortlist of partners, see our guide to programmatic brand safety tools for UK advertisers.
- Set a test window. Run the deal for a defined period with a matched control, then decide whether to scale or stop.
Deal transparency and the questions that matter
A floor price is not a rate card. It is the minimum bid a publisher accepts inside that deal, and it often shifts by format, daypart and device.
Ask how the floor is recalculated. Some publishers review monthly, others hold a floor for a quarter, and the difference changes how your bid strategy performs.
Request the exact fees applicable to the deal in writing. Take rates vary between supply paths, so a generic range would not tell you what this seller charges. If a seller will not separate platform fees from media cost, treat the deal as unverifiable.
Consent considerations for PMP buyers
A PMP narrows the inventory but not your legal duties. If you rely on consent for open marketplace buying, the same basis applies inside the deal. The ICO's UK GDPR guidance explains what counts as valid consent and how to record it.
Our guide to how GDPR consent works for programmatic advertising in the UK sets out the practical steps for UK buyers.
The Privacy and Electronic Communications Regulations 2003 cover cookies and similar technologies. A deal ID or encrypted identifier can fall inside those rules, so check how your tags behave before launch.
The CAP Code, published in the ASA's advertising codes, applies to the ad itself, whatever the deal type. That includes targeting choices and claims made in the creative.
Common questions
Is a PMP cheaper than the open marketplace?
Not usually on a pure CPM basis. You are paying for known inventory, tighter control and often better viewability, so judge it on cost per outcome instead.
What is the difference between a PMP and programmatic direct?
A PMP keeps an auction with a floor. Programmatic direct fixes the price and often the volume, so direct brings more certainty and PMPs bring more flexibility.
How long should a PMP test run?
Thirty to sixty days is usually enough to see whether delivery, viewability and outcomes hold up against your control. Shorter windows rarely give a reliable read.
What should I do if a PMP underperforms?
Ask the seller for a domain-level report first. Weak results often trace back to one or two placements, an unrealistic floor or a fee that swallowed the margin.
