North American Media Experts
Private marketplace CPMs run 2.1x higher than open exchange — but the effective cost per quality impression is nearly identical. Here's what the 2026 benchmark data says about when each deal type wins.
9 min read
When you place a programmatic display or video campaign, one decision sits above bidding strategies, creative formats, and targeting parameters: where are you actually buying your inventory? Open exchange, private marketplace (PMP), or programmatic guaranteed (PG) — each deal type carries fundamentally different cost structures, quality profiles, and performance outcomes.
The data from 2026 tells a clear story. PMP and curated inventory now account for 41% of all programmatic spend, up from roughly 29% just two years ago. At the same time, open exchange's share has fallen from 71% in 2024 to 59% in 2026. This isn't a marginal shift — it's a structural re-routing of billions in media dollars driven by measurable performance gaps between buying environments.
But the right answer for your campaigns isn't always one or the other. This post breaks down exactly what the benchmark data says about each deal type, what you're actually paying per quality impression, and how to build a mixed programmatic strategy that matches your goals.
Before the benchmarks, it helps to define each buying environment clearly:
Most programmatic buyers operate across all three deal types, but the weighting of each has changed dramatically based on performance data. Here's what the numbers say.
The performance gap between open exchange and private marketplace inventory is widening. Industry benchmark data from 2026 shows the following across each deal environment.
On the surface, the open exchange looks like a bargain. But CPM is the least useful metric when buying environments differ this significantly in inventory quality. That's where viewability and fraud data become essential.
Even by the relatively low MRC standard, nearly 30% of open exchange impressions fail the viewability threshold. That gap has real budget implications. For any campaign running a viewability KPI, open exchange inventory creates a structural headwind — not because of poor campaign setup, but because the inventory pool itself contains a high percentage of non-viewable placements that no amount of bidding optimization can fully eliminate.
An 8.7% fraud rate on open exchange means roughly 1 in every 11 impressions you're paying for is invalid — bot traffic, domain spoofing, or ad stacking. According to BidsCube's 2026 brand safety analysis, unfiltered open exchange without pre-bid protection tools can push IVT rates as high as 15–20% in lower-quality verticals. PMP deals are negotiated with known publishers, which structurally limits the attack surface for fraudulent inventory.
When you normalize CPM by viewability and fraud, the apparent gap between open exchange and PMP narrows substantially. Here's the calculation:
An open exchange CPM of $5.85 at 71% viewability and 8.7% fraud works out to an effective fraud-free, viewable cost of approximately $9.45 per thousand quality impressions. A PMP CPM of $12.40 at 92% viewability and 1.2% fraud lands at approximately $13.65 per thousand quality impressions — a gap of roughly $4.20, not $6.55 as the raw CPM difference suggests.
That $4.20 premium per thousand viewable, fraud-adjusted impressions buys you publisher transparency, brand safety controls, stronger contextual alignment, and significantly lower reporting volatility. For campaigns where media quality directly impacts conversion outcomes, that premium typically pays back through lower CPA, higher ROAS, and cleaner attribution data downstream. It's also worth noting that PMP inventory's superior viewability means your retargeting audiences are built on users who actually saw the ad — not bots or people who had the ad below the fold.
The budget shift toward curated inventory is happening across the industry, not just among premium brands:
This trend is partially driven by supply path optimization (SPO) initiatives, where brands and agencies are using AI-assisted tools to audit their programmatic supply chains and route spend through fewer, higher-quality paths. Most major DSPs now have dedicated SPO features that automatically identify and prioritize curated supply when it's available for a given audience target.
Curated marketplaces — where an SSP or data provider aggregates high-quality inventory from multiple publishers around a topic, audience, or quality floor — are also growing rapidly as a middle ground. They offer PMP-like quality without requiring direct publisher relationships or high spend minimums, making them accessible to mid-market advertisers who can't negotiate one-to-one PMP deals at scale.
The data makes a clear case for matching deal type to objective. Here's how the analysis breaks down.
Open exchange remains the right choice when you need maximum audience reach at low cost-per-impression for top-of-funnel prospecting, you're running broad campaigns with strong pre-bid audience data that carries contextual signals independent of placement quality, you're in a direct-response vertical where viewability optimization via pre-bid filtering can compensate for open exchange quality variability, or your DSP is already running real-time algorithmic optimization with third-party fraud verification active on every bid.
The caveat: open exchange without pre-bid filtering is a budget leak. If you're running open exchange inventory without a viewability pre-bid filter (available in The Trade Desk, DV360, Amazon DSP, and most other major platforms), you are paying for a large share of non-viewable impressions. This is a configuration issue, not an inherent limitation of the deal type.
Private marketplace deals outperform when you have a viewability KPI of 70% or higher — open exchange inventory makes this target structurally difficult to hit consistently. PMPs also win when your campaign runs in a regulated or brand-sensitive vertical like financial services, healthcare, or luxury where placement context matters. Importantly, PMPs are the right environment when you're activating first-party data against specific publisher audiences — the combination of your own CRM data with curated publisher inventory typically improves match rate performance and downstream conversion quality significantly.
PG is the right choice for seasonal or tentpole campaigns where specific publisher positions (homepage takeovers, category sponsorships) must be reserved, high-budget brand campaigns where premium publisher alignment is part of the brand strategy rather than just a performance consideration, and situations where you need precise impression delivery — a fixed number of guaranteed impressions against a premium placement with no risk of under-delivery.
The PMP premium delivers uneven returns across industries. Some verticals see dramatically higher lift from curated inventory because of audience characteristics and conversion path complexity:
The best-performing programmatic strategies in 2026 don't choose exclusively between open exchange and PMP. They allocate intentionally across deal types based on funnel stage and audience signal strength. According to Epom's 2026 programmatic analysis, the highest-spending buyers now structure their media plans as follows:
If you're not sure what percentage of your programmatic budget is currently flowing through each deal type, or whether your CPM benchmarks match the quality you're actually getting, that's the starting question for a programmatic strategy review. Most brands find meaningful reallocation opportunities when they examine their supply path data for the first time.
Not always. The premium justifies itself most clearly when you have a viewability KPI above 70%, a brand safety mandate, or first-party audience data that performs better against known publisher inventory. For pure volume-based prospecting with strong algorithmic optimization and pre-bid filtering active, open exchange can deliver a lower effective cost per quality impression than PMP — especially at the top of the funnel where reach matters more than placement context.
Most DSPs (The Trade Desk, DV360, Amazon DSP, StackAdapt) have marketplace deal libraries where publishers list available PMP opportunities. You can also work with a programmatic partner who manages supply path relationships and can negotiate PMP access on your behalf — particularly valuable if your spend doesn't yet qualify for direct publisher minimums, which often start at $25,000–$50,000 per month for top-tier publishers.
A PMP deal is negotiated directly between a buyer and a specific publisher. A curated marketplace deal is created by a third party — often an SSP or data provider — that aggregates inventory from multiple publishers around a theme, audience segment, or quality floor. Curated deals offer PMP-like quality at more accessible minimums, making them a strong option for mid-market advertisers who can't reach direct PMP minimum thresholds.
Programmatic guaranteed is best suited for large brand campaigns with specific placement requirements and substantial budgets, typically $50,000+ per placement. For most mid-market advertisers, PMP deals offer the quality benefits of direct inventory without the reserved volume commitments that PG requires.
Open exchange is accessible to all buyers, which means fraudulent publishers can also access it more easily. PMP and PG deals are negotiated with known, vetted publishers — which structurally limits domain spoofing and bot traffic at the supply level. Pre-bid verification tools (IAS, DoubleVerify, MOAT) add an important safety layer on open exchange, but they filter impressions you've already bid on rather than preventing fraud at the supply source. PMP deals address fraud upstream.
If you're not sure what percentage of your programmatic budget is flowing through open exchange versus curated inventory — or whether your current CPM benchmarks reflect the quality you're actually getting — a programmatic audit will surface it quickly.
Book a free intro call with our team to walk through your current programmatic setup, deal type allocation, and supply path efficiency. Or request a free programmatic audit and we'll review your CPM-to-quality ratios, fraud exposure, and deal type mix to identify where your media dollars are working hardest — and where they're not.