SPO Fatigue: Why Agencies Are Questioning Supply Path Optimization’s Real ROI

Every industry eventually produces a term that starts as a genuine insight and slowly hardens into a slide-deck reflex. In programmatic advertising, that term is supply path optimization. When SPO first entered agency vocabulary, it named a real and uncomfortable truth: that a large share of digital ad spend was disappearing into a supply chain nobody could fully see, split across exchanges, resellers, and intermediaries that added cost without adding value. Fixing that felt urgent, and agencies that built SPO capability early earned a genuine competitive edge. What is happening now, several years into that build-out, is a quieter and more uncomfortable reckoning. The edge has dulled, the workload has not, and a growing number of agency leaders are asking whether SPO delivered the return it promised, or simply relocated the industry’s complexity problem from the media supply chain into the agency’s own operations.

The term making the rounds in trading desk conversations across the country is SPO fatigue, and it captures something more specific than general skepticism about ad tech. Nobody disputes that duplicate bidding, opaque fee stacks, and low-quality reseller inventory are problems worth solving. What has changed is the confidence that solving them requires the scale of infrastructure many agencies built to do it. An SPO practice that once looked like disciplined stewardship of client budgets now, in some cases, looks like a standing cost center whose returns are difficult to isolate and harder still to defend in a client review.

That difficulty is worth sitting with, because it is the crux of the current mood. SPO’s original business case rested on industry-level waste studies, the kind that showed meaningful percentages of ad spend vanishing into unattributed supply chain costs. Those studies were credible and the waste was real. But a campaign-level ROI case is a different exercise altogether. Proving that a specific supply path change improved a specific client’s outcomes, net of the cost of the tooling and headcount used to make and monitor that change, requires an attribution rigor that few agencies, even sophisticated ones, have fully built. In the absence of that rigor, SPO has often been sold and defended on narrative: cleaner paths, fewer intermediaries, more transparency. Those are reasonable things to want. They are not, on their own, numbers a CFO can hold an agency accountable to.

Agencies that have run SPO programs for two or three years now have enough internal history to notice the pattern themselves. A curated private marketplace deal, negotiated over months and pitched as premium, ends up performing statistically indistinguishable from the open exchange inventory it replaced. An SSP consolidation project, executed carefully and audited thoroughly, yields single-digit efficiency gains that are partially or fully offset by the licensing cost of the transparency and curation tools used to run the project. None of this is dramatic. It is the accumulation of modestly disappointing outcomes that eventually forces a harder question: is the agency optimizing the supply chain, or maintaining an increasingly expensive apparatus for monitoring a supply chain that has not gotten meaningfully cleaner?

There is a structural reason this apparatus keeps growing even as its returns plateau. SPO was framed as a disintermediation exercise, a way of removing unnecessary layers between advertiser and publisher. In practice, the tools built to execute that exercise have themselves become a layer. Curation platforms, SPO-as-a-service vendors, log-level reporting dashboards, and supply chain transparency consultancies now sit between the agency and the media it buys, each charging a fee and each claiming to be the authoritative source on where the waste actually is. An agency serious about SPO today is not managing one relationship with a handful of clean SSPs; it is managing a small ecosystem of vendors whose primary function is helping the agency decide which other vendors to trust. That is not the simplification SPO was supposed to deliver. It is a more sophisticated version of the same fragmentation.

This is where agency-client conversations have visibly shifted. Two or three years ago, an SPO section in a quarterly business review was a credibility marker, proof that the agency understood the mechanics behind the media, not just the media itself. That section still appears in most reviews, but the questions that follow it have sharpened. Clients, particularly finance-literate marketing leads at larger advertisers, are asking for the rupee figure attached to the optimization work, and they are asking what portion of any efficiency gain was consumed by the cost of achieving it. Agencies that built their SPO narrative on process rather than proof are finding that narrative increasingly insufficient. The ones holding up better are the ones that quietly built measurement discipline alongside the optimization work, rather than treating the optimization itself as the deliverable.

None of this amounts to an argument that the underlying problem has gone away. If anything, the supply chain has grown more complicated since SPO first became a priority. Retail media networks have added an entirely new category of inventory with its own fee structures and reporting standards. CTV has fragmented supply across app-based, device-based, and operator-based paths that rarely reconcile cleanly with one another. Clean rooms and identity resolution vendors have inserted themselves into the buying process with their own cost lines. The waste SPO set out to eliminate has not disappeared; it has simply found new places to hide. What has changed is not the scale of the problem but the industry’s willingness to throw undifferentiated effort at every corner of it.

The more interesting shift, and arguably the healthier one, is in how leading agencies are choosing to respond. Rather than abandoning SPO, they are narrowing its scope with real discipline. Instead of auditing every SSP relationship with equal intensity, several trading desks are now concentrating optimization effort on the small number of supply sources, typically three to five, that carry the overwhelming majority of programmatic spend, and applying a much lighter, more automated review to the long tail. Instead of defaulting to curated deals as a badge of sophistication, some agencies are reverting to well-monitored open exchange paths for lower-stakes campaigns and reserving curation budget for high-value CTV or performance work where inventory quality differences are large enough to matter and measurable enough to prove.

Underneath that narrowing is a bigger philosophical move: treating raw, auditable data as more valuable than any single vendor’s optimization narrative. An agency that can pull clean log-level data and interrogate it independently is in a stronger negotiating position with every SSP, DSP, and curation partner it works with, regardless of how many supply paths it has technically consolidated. Several forward-looking programmatic teams are shifting budget away from pure path-narrowing exercises and toward data infrastructure and internal analytics capability, on the logic that visibility, not consolidation, is the actual lever that produces defensible savings. That is a subtle but significant repositioning of what SPO is supposed to mean.

It would be unfair to lay all of this at the feet of the vendors who built the SPO and curation category; several of them are responding to a genuine gap that agencies could not fill on their own, and some curation platforms have demonstrably improved inventory quality for the clients that use them well. Their pushback on the fatigue narrative, that the disappointment reflects poor implementation rather than a flawed premise, deserves a fair hearing. Agencies that treated SPO as a one-off project rather than an evolving discipline, or that adopted curation tools without building the internal capability to interrogate their output, were always going to see diminishing returns regardless of how sound the underlying logic was. The failure, where it exists, is often one of execution and expectation-setting rather than concept.

What is emerging from this period of recalibration looks less like the SPO of three years ago and more like a quieter, more evidence-driven discipline embedded within a broader efficiency practice. Fewer blanket consolidation mandates, more targeted intervention justified by actual numbers. Less trust placed in vendor-supplied efficiency stories, more insistence on data the agency can independently verify. Less use of SPO as a marketing term meant to signal sophistication, and more treatment of it as one input among several, sitting alongside creative effectiveness, audience strategy, and measurement, rather than standing apart as the industry’s singular answer to programmatic waste. That is a less glamorous position than the one SPO occupied at its peak. It is also, for an industry that spent years treating it as close to a cure-all, a considerably more honest one. The fatigue is not evidence that SPO failed. It is evidence that agencies are finally applying to it the same scrutiny they apply to every other line item on a media plan: show the number, or lose the budget.