How OpenPath drove 8.1% lower CPMs via supply path competition

Media buyers have more than one way to access digital inventory programmatically. With multiple supply paths available for the same ad impression, understanding how inventory is sourced has become an important part of driving efficiency and getting more value from media investments. 

A more transparent supply path can help buyers better understand where their media dollars are going, how efficiently they are accessing inventory, and which partners are creating the most value. The study found that campaigns with access to both OpenPath and SSP inventory also saw lower CPMs than campaigns targeting one path alone, suggesting that OpenPath may create additional value by encouraging stronger supply path competition.¹ 

Why supply path competition matters 

Supply path optimization (SPO) is often framed as an efficiency play to remove unnecessary hops, reduce waste, and improve transparency. 

In programmatic advertising, the same impression can often be available through multiple routes, each with different economics, signals, and levels of visibility. When you cannot see or compare those paths clearly, it can be harder to understand which route is delivering the most value. 

But SPO is also a performance lever. 

Buyers need to be able to evaluate how inventory is accessed, compare path-level economics, and make decisions based on transparency, efficiency, and performance. Competition is central to that process. When you have more than one viable path to supply, each path has a stronger reason to compete. That can encourage more competitive pricing and create incentives for supply partners to deliver better value. 

What the analysis found 

Our study looked at about 1,000 campaigns across more than 500 advertisers, representing more than $21 million in spend. The analysis covered campaigns that targeted both OpenPath and SSP inventory over 30 days. Campaigns were selected at random to help rule out variables that could influence results. 

For each campaign, the team compared spend through both OpenPath and SSP paths with spend through SSP paths alone.

Across every measured channel, campaigns with access to both OpenPath and SSP inventory saw lower CPMs, on average. 

The findings suggest that the presence of OpenPath may help encourage more competitive pricing across the broader programmatic ecosystem. When you have access to a more direct supply path, other paths have more of an incentive to remain competitive in a way that benefits buyers. 

What this means for buyers 

OpenPath gives you another way to evaluate the supply chain. That can help you answer practical questions, like: 

• Which paths are giving us the most efficient access to the same or similar inventory? 

• Where are we seeing stronger pricing, signal quality, or win rates? 

• Where can supply path decisions improve campaign economics? 

Supply path decisions affect CPM, but they can also influence transparency, signal quality, bidding confidence, and the amount of budget that reaches working media. OpenPath can give buyers a clearer point of comparison.

How to put supply path competition into practice 

SPO works best as an ongoing discipline.

Start by looking at where you have access to multiple supply paths and comparing performance across those routes. OpenPath can serve as one benchmark for understanding how a more direct path performs against alternative paths. 

As you evaluate supply path performance, consider: 

• Path-level efficiency: Compare CPMs, fees, and working media across available routes. 

• Transparency: Understand where impressions are purchased and how supply paths differ. 

• Signal quality: Evaluate whether each path provides the information needed to value impressions more accurately. 

• Win rates and access: Understand which paths provide the best access to the inventory that matters most to your campaign. 

• Campaign outcomes: Look beyond cost to understand how supply path choices affect broader performance goals. 

The best supply path strategy is one that gives you flexibility. With greater visibility into available inventory paths, you can choose the route that offers the right combination of efficiency, transparency, and value. 

OpenPath can help create that flexibility. By adding a more direct route to premium inventory, it can help buyers improve efficiency, benchmark alternative paths, and encourage stronger competition across the supply chain.

To learn more about how OpenPath can help you take advantage of greater supply path competition, get in touch with your representative at The Trade Desk today. 

This information is provided solely for background and is not a representation or guarantee of any future performance. 

<sub>Source:
1. The Trade Desk Platform Data. Internal analysis, April to May 2026. Analysis included 980 campaigns, 517 advertisers, and $21.5 million in spend.</sub>