June 2, 2026 · 5 min read
We Measured Actual Savings From Supply Path Optimization
Supply path optimization promises to cut out redundant intermediaries. We measured what it actually saved on a real campaign, and the number surprised us in both directions.
Supply path optimization gets pitched as a straightforward win — cut the redundant intermediaries between advertiser and publisher, keep more of the budget actually reaching impressions. The theory is sound. We wanted an actual number, so we measured one campaign carefully, before and after an SPO cleanup.
What we found going in
The campaign was buying the same inventory through four different reseller paths without realizing it, because each path presented itself through a different SSP relationship with no obvious overlap visible in the DSP's reporting. We mapped actual impression-level overlap using bid request data, which took real analyst time but revealed genuine duplication — the same ad slot available through paths with meaningfully different take rates.
Supply path duplication doesn't show up as an error anywhere. It shows up as money quietly leaking through a path nobody mapped, dressed up as normal programmatic noise.
The measured result
- Consolidating to the two lowest-take-rate paths for overlapping inventory recovered roughly 9% of total media spend into actual impressions — real, but meaningfully below some of the 15-20% figures vendors cite.
- A chunk of the theoretical savings from the vendor's own SPO analysis tool turned out to be inventory that wasn't actually duplicated, just similar-looking — the tool's overlap detection had a real false-positive rate we had to manually verify.
- The analyst time required to properly verify overlap, rather than trusting the automated tool's output blindly, was substantial — probably not worth it below a certain campaign spend threshold.
- Above that threshold, the 9% recovered was genuine and repeatable quarter over quarter, which made the ongoing monitoring worth maintaining.
SPO works, but the number worth budgeting for is closer to high single digits than the headline figures vendors advertise, and getting even that requires real verification work rather than trusting an automated overlap report at face value.