WPP, dentsu step back from The Trade Desk’s OpenPath over transparency concerns

Two of the world’s largest advertising holding companies — Dentsu and WPP — are believed to have quietly stepped back from The Trade Desk’s OpenPath, a direct-to-publisher buying initiative launched in 2022. 

OpenPath was positioned as a way for advertisers to buy inventory directly from publishers, bypassing multiple intermediaries. The initiative was positioned as a way to improve campaign performance, enhance transparency, and reduce inefficiencies in programmatic transactions.

However, according to a report by AdWeek, two agencies have expressed reservations around aspects such as fee visibility, transparency, and clarity on ad placements, prompting a reassessment of their participation.

The development signals emerging friction between large agency groups and ad-tech platforms as the industry debates control and transparency across the programmatic advertising supply chain.

Another consideration, according to industry observers, is the potential overlap between OpenPath and services traditionally handled by agency trading desks, including supply-path optimisation (SPO) and inventory curation.

WPP and Dentsu did not respond to calls and messages for a comment.

The Trade Desk’s response

Executives at The Trade Desk have pushed back on suggestions that OpenPath involves undisclosed costs, emphasising that the initiative is designed to create a more efficient supply path for advertisers. 

In a response to e4m queries, The Trade Desk claims that the platform is transparent and growing. 

“OpenPath is just one example of our supply chain initiatives—all developed in collaboration with brands and agencies—to drive transparency, value and choice. Buyers have en route to any given impression, and spend flowing through OpenPath has been growing steadily over the last year or so. The primary reason that it has been so successful is that it is the clearest, most cost-efficient path with the highest signal.”

“TTD doesn’t push spend to OpenPath. It’s not a marketplace or curated inventory. OpenPath is simply a supply path option to ad impressions an advertiser would already be targeting. OpenPath is offered at cost to the ecosystem. We’ve been clear about that. There are no hidden fees beyond that. If OpenPath is selected by an advertiser, it’s simply because it’s the cleanest, most cost-efficient path,” Ian Colley, Chief Marketing Officer and EVP at The Trade Desk, said, replying to a LinkedIn post shared by AdWeek. 

Who controls the supply chain?

The development highlights a broader tension within the digital advertising ecosystem. As demand-side platforms (DSPs) expand deeper into the supply chain, agencies are increasingly focused on maintaining visibility and control over inventory routing and pricing dynamics.

OpenPath was designed to provide advertisers with a more direct route to publisher inventory—an approach The Trade Desk has positioned as an alternative to vertically integrated ad ecosystems such as Google’s advertising stack.

However, as DSPs move closer to the supply side of the marketplace, agencies and publishers often seek greater clarity around auction dynamics, fee structures, and inventory sourcing. For advertisers managing large budgets across channels such as display, connected TV, and audio, these factors can influence campaign performance and accountability.

Shifting alliances in ad-tech

The pullback also reflects evolving alliances across the programmatic ecosystem.

Large agency groups frequently maintain strategic partnerships with specific ad-tech platforms, shaping where significant portions of client media budgets are directed. These relationships often influence technology adoption and platform scale within the broader advertising marketplace.

As DSPs expand their capabilities and push deeper into the supply chain, agencies and advertisers are expected to place greater emphasis on transparency, inventory quality, and decision-making visibility.

For The Trade Desk, which has positioned OpenPath as a key component of its long-term strategy, continued engagement with agency partners will remain important as competition intensifies across the global ad-tech landscape.