When a programmatic advertising campaign comes in soft, we tend to reach for the same two explanations: the budget was too small or the targeting was off. The ANA’s Q1 2026 Programmatic Transparency Benchmark suggests we’ve been looking in the wrong place. It recorded the widest performance gap in the study’s history, 21.9 points between the top and bottom halves of advertisers. The top half turned 54% of its programmatic advertising spend into qualified impressions, while the bottom half managed 32%.
But what was more surprising to me was that transaction costs (the fees everyone renegotiates at renewal time) separated the two groups by just 2.4 points. Almost the entire gap came down to media productivity, or how much of each dollar equated to a quality impression in the first place.
Audience targeting decides who is eligible, not what you buy
Most programmatic advertising strategy still starts and ends with the audience question. First-party data, third-party overlays and lookalike models are all aimed at the people who see the ad. That work matters, but it only settles eligibility. It decides who could see your impression, not the quality, price or context of the inventory that impression runs on.
When you layer a tight audience onto open-exchange inventory, you’re usually bidding for the same impressions as every other buyer chasing that segment. That can push effective costs up even though the environment your ad lands in doesn’t necessarily improve.
Yet an agency trader may say, we want to find the audience anywhere, but is the audience really anywhere? The inventory beneath the audience layer does much of the work that determines your outcome, and it rarely receives the same thorough consideration as an audience tactic.
The hidden math of open-auction buying
When you buy through open auction, your bid and your delivered value are two different numbers. Supply-side platform fees are embedded across the chain in ways that never surface cleanly on an invoice, and demand-side platform costs sit on top of that. Once you also subtract the impressions that were non-viewable, non-measurable or served somewhere you can’t verify, and the platform costs, the real cost per impression looks nothing like the CPM you agreed to.
Let’s look at the benchmark report again.
Lower-performing advertisers lost 38.4% of their spend to quality issues like non-measurable and non-viewable inventory, while the top group lost 19%. The study also found consistent, quarter-over-quarter differences between the two cohorts in supply concentration, measurement coverage and quality control.
In plain terms, the advertisers pulling ahead run with inventory from fewer supply-side platforms, buy through more deliberate publisher or curated paths and reach for open exchange selectively rather than defaulting to it.
In other words, they’re treating supply as a variable that they manage, and thereby exert more control over it.
The supply side can do more than most buyers ask of it
The default programmatic advertising motion is to take whatever supply an exchange offers and apply audience targeting inside the demand-side platform. In the campaigns I see across agencies and marketers, that motion leaves real capability on the table, because a supply partner can do far more than hand you inventory.
Curated private marketplaces, first-party audience matching on the sell side and audience graphs built into a supplier’s platform all let you shape the environment before demand-side targeting enters the picture. You don’t need to pull a package off the shelf because a preferred partner says they’ve done the hard work for you. Instead, you can curate against the actual brief and build a more direct path to the inventory you want with better audience match rates. Many supply and streaming partners also carry their own verified, sign-up-based audience data available right at the point of inventory selection. This offers a strong path for verticals where bringing data into a demand-side platform is restricted or fragmented.
Price works the same way. A large share of inventory still routes through default exchanges, such as Google Ad Manager on DV360, which isn’t a problem in itself. But publishers will tell you they earn higher margins by negotiating one-to-one with a verified supply-side platform.
And while buyers don’t tend to think as much about a publisher’s margins, buyers who take that same route often get cleaner inventory and better pricing than they would running open exchanges across a stack of exchanges. The reason why? Better margin for the publisher, more negotiating room for you. If you spin up a deal inside your demand-side platform, you’ll get convenience at the market price.
But if you negotiate through a partner built to source premium supply, you have more control over what you’ll pay.
There’s also a timing reason to look harder at the supply side. Audience data is only as reliable as the behavior underneath it, and that behavior is shifting. Audiences based on search signals raise questions because search itself is changing as AI overviews reshape results, and younger users start their queries on TikTok or an AI assistant instead of a search bar. Leaning entirely on an audience layer assumes that signal holds steady, while pushing audience data into the supply path makes for less reliance on demand-side audience signals.
How to know whether supply is working for you
You don’t need to rebuild your programmatic advertising practice to close this gap. Instead, before your next flight, look at the inventory the way the top-performing advertisers in the benchmark do.
Here are some questions to consider:
- Is the supply direct, and can the partner tell you where it originates?
- How many fee layers sit between your bid and the publisher, and which ones show up on your invoice?
- Are you using your supply partners’ curation and audience tools, or pulling standard deals off the shelf?
- For connected TV and online video, are you talking to the major streamers directly? Buying a publisher solely through an intermediary can mean missing out on added-value capabilities, such as interactive formats or sponsorships, that only come through a direct conversation.
- What share of your delivered impressions is genuinely viewable, measurable and free of made-for-advertising inventory?
Some of these questions do add a planning step and a few pointed conversations. However, in taking the extra steps, you start to see which partners have the best inventory for your brief. As marketers ask agencies for more transparency – and those calls are only getting louder – that same expectation has to run all the way down the chain to the publishers and platforms that source the inventory.
You don’t have to overhaul anything to move up in this benchmark. Start with one campaign and compare results to previous campaigns with similar criteria. Agencies have as much of a right to hold their partners to the same transparency as their clients are beginning to expect.
Every dollar put in working media is another impression in front of a real person, and across a year of buying, that discipline is the gap the benchmark keeps measuring.
Opinions expressed by SmartBrief contributors are their own.
____________________________________
If you liked this article, sign up for the SmartBrief Marketing Pulse, a daily look at the latest in shifts and performance data for marketers.