How many sites should a private marketplace deal include? It is one of the most useful questions a luxury brand can ask its agency, and one of the least asked. A private marketplace, or PMP, is sold as a premium, invitation-only slice of programmatic supply. Some are exactly that: a few dozen high-quality publishers, priced fairly and reported transparently. Others are open-exchange inventory with a deal ID and a higher price. The difference usually comes down to one number: how many domains and apps the deal contains. This guide explains what the research says, what the right range looks like for high-consideration brands, and how to check what is actually inside the deals you are paying for.
Why Does the Number of Sites in a PMP Matter?
A private marketplace is a deal between a buyer and a seller, usually set up in a supply-side platform and activated in the buyer's DSP with a deal ID. The deal defines who can bid, the floor price and the inventory included. Nothing in the mechanism limits how much inventory goes in. A single publisher can offer a PMP covering its own flagship site. A curator or SSP can package thousands of domains into one deal and still call it private.
That flexibility is why size matters. The more sites a deal contains, the more it starts to resemble the open marketplace, with the same mix of premium publishers, long-tail sites and made-for-advertising (MFA) inventory, but at PMP prices. If you have read our guide to open exchange vs private marketplace programmatic, you know the PMP premium is only worth paying when the supply is materially better.
What Did the ANA Find About PMP Size and Quality?
The clearest evidence comes from the ANA's 2023 Programmatic Media Supply Chain Transparency Study, which analyzed actual log-level data from participating advertisers. Its findings on private marketplaces are blunt:
- Large PMPs looked like the open market. According to TAG TrustNet's summary of the study, PMPs with more than 500 domains delivered quality similar to open marketplace deals, but at roughly double the cost.
- MFA exposure tracked deal size. As Reed Smith's review of the ANA findings reports, open marketplace buys averaged 26.8% MFA impressions, PMPs with more than 500 domains averaged 19.8%, and PMPs with 11 to 500 domains averaged 1.3%.
- PMPs were not automatically clean. An average of 14% of spend within PMPs went to MFA inventory across the study.
- Campaigns were spread far too wide. The average campaign ran on about 44,000 sites. The ANA suggested most advertisers could work with a far smaller set of trusted sellers and should prioritize inclusion lists over exclusion lists.
The pattern since then has not reversed. The ANA's quarterly Programmatic Transparency Benchmark, summarized for Q2 2026 by Fiducia, found that higher-performing advertisers operated across roughly 19,000 fewer domains and apps than lower performers. Concentration and quality go together.
How Many Sites Should a Private Marketplace Deal Include for a Luxury Brand?
There is no single correct number, but there are clear bands. For a luxury or high-consideration brand, the right size depends on what the deal is for. The table below summarizes how we think about it. These are Stillwater planning ranges based on our own buying, not an industry standard.
| Deal type | Typical domain or app count | What it is good for | Main risk |
|---|---|---|---|
| Single-publisher PMP | 1 to 10 | Flagship editorial environments, premium CTV apps, sponsorship-adjacent placements | Limited scale; higher CPMs |
| Curated premium PMP | 11 to 150 | Core prospecting against affluent audiences across vetted publishers | Curator fees; needs regular list review |
| Broad curated PMP | 150 to 500 | Scaled reach with some quality control | Quality drift as lists grow |
| Mega-PMP | 500+ | Rarely justified for luxury brands | Open-market quality at PMP prices |
| Open marketplace | Thousands to tens of thousands | Testing, retargeting with strict inclusion lists | MFA, fraud and brand safety exposure |
For most of the brands we work with, the core of the plan sits in the first two rows: a handful of single-publisher deals for the environments that matter most, and curated deals in the range of roughly 25 to 150 domains or apps for scaled prospecting. A deal that grows past 500 should be treated as open-market supply until proven otherwise.
Is a smaller PMP always better?
No. A deal with five sites can still be the wrong five sites, and an extremely narrow deal can starve your DSP's optimization or push frequency too high on a small audience. The goal is not the smallest possible list. It is a list where every domain or app is one you would choose on purpose. Our guide to programmatic curation for luxury brands covers how good curators build and maintain those lists.
Does the right number change for CTV?
Yes. CTV deals are measured in apps and channels rather than websites, and premium streaming supply is concentrated in a smaller number of publishers. A well-built CTV PMP for affluent audiences might include a handful of premium streaming services plus a short list of vetted publisher apps. A CTV deal advertising thousands of apps almost certainly includes low-quality FAST channels and unbranded inventory that a luxury brand would not knowingly buy.
How Many Sites Should a Private Marketplace Deal Include When Scale Matters?
The most common objection to small deals is scale. A brand selling a $3 million residence or a private aviation membership needs reach into a narrow audience, and a deal with 30 publishers can feel restrictive. In practice, scale for affluent audiences comes less from adding domains and more from adding the right formats and environments.
Consider where an affluent buyer actually spends attention: premium streaming on a television, a handful of trusted financial, business and lifestyle publications, podcasts, and a few high-quality apps. Adding the 400th domain to a deal rarely adds a new buyer. It mostly adds cheaper impressions in front of the same people, or in front of no one in particular. When a plan needs more reach, three moves usually work better than inflating a PMP:
- Add channels, not domains. Premium CTV, streaming audio and DOOH extend reach into the same affluent households in different moments.
- Add a second curated deal with a different editorial focus. Two deals of 60 domains each, one built around business and finance and one around travel and design, usually outperform one deal of 600.
- Widen the audience, not the supply. Loosen audience filters on high-quality inventory before loosening inventory filters on a tight audience.
Scale built this way keeps the reporting readable. You can still name every publisher that carried your brand, which matters for brand safety, for creative decisions and for explaining results to a CFO.
How Do You Know What Is Inside a PMP?
Most advertisers never see the inventory list for the deals they buy. Ask for it before activation and verify it after. A practical process:
- Request the deal manifest. Ask the seller or curator for the full list of domains and app bundle IDs in the deal, and how often it changes.
- Compare the manifest with delivery. After two weeks, pull a placement report from your DSP and check where impressions actually ran. Deals sometimes deliver on inventory outside the manifest, especially when resellers are involved.
- Check the long tail. Sort placements by impressions and look at everything outside the top 50. That is where MFA and low-quality supply hide.
- Run MFA and fraud screening. Use your verification partner's MFA classification and invalid traffic reporting on the deal, not just on the campaign total.
- Ask for log-level data where possible. Log-level data shows the full supply path and fees. The ANA study relied on it for a reason.
- Review quarterly. Curated lists drift. A deal that started at 40 domains can quietly grow to 400.
Our guides to brand safety in programmatic advertising and supply path optimization for premium advertising go deeper on verification and on cutting unnecessary resellers.
What Questions Should You Ask Before Buying a PMP?
Use these with any agency, SSP or curator offering a private marketplace deal:
- How many domains and apps are in this deal today, and what was the count three months ago?
- Can we see the full manifest before launch?
- Who curates the list, and what are the criteria for adding a site?
- Is MFA inventory excluded, and whose classification is used?
- Are any of the sites sold through resellers rather than directly?
- What curation or data fees sit on top of the publisher's floor price?
- Will you share placement-level delivery reports for this deal specifically?
- Can we remove domains or apps from the deal on request?
If the answers are vague, treat the deal as open-market supply and price it accordingly.
How Does PMP Size Affect Cost and Performance?
Price and quality do not move together automatically. The ANA's finding that large PMPs delivered open-market quality at double the cost is the warning. A smaller, well-curated deal usually carries a higher headline CPM but a lower cost per quality impression, because fewer impressions are wasted on MFA, low-viewability or fraudulent placements.
Stillwater planning ranges for affluent-audience campaigns:
- Single-publisher display PMPs: $18 to $40 CPM all-in.
- Curated premium display PMPs (25 to 150 domains): $12 to $28 CPM all-in.
- Premium CTV PMPs: $35 to $70 CPM all-in, depending on publisher and targeting.
- Long-tail share in a healthy PMP: under 10% of impressions outside the top 50 placements.
- MFA share in a healthy PMP: effectively zero, with any MFA delivery flagged and credited.
Judge each deal on cost per qualified outcome, not CPM. A $14 CPM on a 900-domain deal that produces no qualified inquiries is more expensive than a $30 CPM on 30 premium publishers that does. Our private marketplace deals guide explains how to structure those comparisons.
Common Mistakes When Sizing Private Marketplace Deals
- Assuming "private" means premium. The label describes the transaction, not the inventory.
- Never asking for the manifest. If you do not know what is in the deal, you cannot judge its price.
- Letting deals grow unchecked. Curators add inventory to hit scale targets. Set a ceiling in writing.
- Buying the same publishers twice. Overlapping PMPs from different curators can bid against each other for the same impression and inflate your costs.
- Using exclusion lists only. Blocking known bad sites leaves the door open to new ones. Inclusion lists are the stronger control, as the ANA recommended.
- Judging deals on CTR. Click-through rate rewards the accidental-click inventory that large deals often contain.
- Ignoring vertical context. A wealth management brand needs financial and business editorial environments; a private club or hospitality brand needs travel, lifestyle and culture. One generic "premium" deal rarely fits both. Our wealth management advertising page shows how we think about environment selection in a regulated category.
How Many Sites Should a Private Marketplace Deal Include? The Short Answer
If you need a single rule to take into your next agency meeting: a curated private marketplace deal for a luxury or high-consideration brand should usually include somewhere between 25 and 150 domains or apps, every one of which you can see, name and remove. Single-publisher deals can be smaller. Anything above 500 should be priced and judged like open-market supply, because the ANA's data says that is how it performs.
How Should a Luxury Brand Structure Its PMP Portfolio?
A durable structure for a high-consideration brand usually has three layers:
- Anchor deals: three to eight single-publisher or programmatic guaranteed deals with the environments your buyers trust most, including premium CTV.
- Curated prospecting deals: two to four curated PMPs of roughly 25 to 150 domains or apps each, aligned to your audience and vertical, with manifests reviewed quarterly.
- Controlled open-market tests: a small share of budget on the open exchange with strict inclusion lists, used to find new publishers worth promoting into PMPs.
Measure the whole portfolio with incrementality testing, not just platform attribution, so you know which deals actually move qualified demand.
Buy Deals You Can See Inside
Stillwater Media is a selective performance media agency for luxury and high-consideration brands. We build private marketplace deals, premium CTV, programmatic, DOOH and streaming audio plans around curated supply, transparent pricing and incrementality testing, and we take on a limited number of engagements each quarter.
If you want to know how many sites are really inside your current PMPs, apply to work with Stillwater Media and we will review the deals with you.
About the author: Stillwater Media is a selective performance media agency for luxury and high-consideration brands, headquartered in Charlotte, NC and working with clients nationally and internationally. The team plans premium CTV, programmatic, affluent audience targeting, DOOH, streaming audio, YouTube Select, podcasts, native and social for brands where customer lifetime value exceeds $5,000 and sales cycles run longer than 30 days, including private aviation, luxury real estate, wealth management, private clubs, luxury automotive, premium DTC and luxury hospitality. Signal. Strategy. Scale.
Frequently Asked Questions
How many sites should a private marketplace deal include?
For luxury and high-consideration brands, most curated private marketplace deals work best with roughly 25 to 150 vetted domains or apps, alongside single-publisher deals of 1 to 10 sites for flagship environments. Deals with more than 500 domains tend to deliver open-market quality at PMP prices, according to the ANA's 2023 transparency study.
Are private marketplace deals always higher quality than the open exchange?
No. The ANA found that an average of 14% of spend within PMPs went to made-for-advertising inventory, and PMPs with more than 500 domains performed similarly to the open marketplace at about double the cost. A PMP is only premium if the inventory inside it is.
How much MFA inventory is in a typical PMP?
It depends heavily on size. In the ANA study, PMPs with 11 to 500 domains averaged 1.3% MFA impressions, while PMPs with more than 500 domains averaged 19.8%, compared with 26.8% on the open marketplace.
How can I see which sites are in my PMP deals?
Ask the seller or curator for the deal manifest listing every domain and app bundle ID before launch, then compare it with a placement-level delivery report from your DSP after the campaign starts. Screen the long tail with your verification partner's MFA and invalid traffic reporting, and review the list every quarter.
Should a luxury brand use inclusion lists or exclusion lists?
Inclusion lists are the stronger control because they allow only sites you have approved, while exclusion lists only block sites you already know are bad. The ANA recommended prioritizing inclusion lists, and they pair naturally with small, curated private marketplace deals.
