What the OpenPath Fallout Reveals About the State of CTV Media Buying

Update - This article was originally published after learning that Dentsu and WPP were leaving The Trade Desk's OpenPath platform. We called it a structural problem, not a vendor one. This week, Publicis, the world's largest holding company, advised clients to stop using The Trade Desk, citing a failed transparency audit. If what we described below was the early warning, this is confirmation. The industry is starting to catch up.

Earlier, Adweek broke the news that Dentsu and WPP - two of the world's largest advertising holding companies - quietly exited The Trade Desk's OpenPath platform. The reason? Hidden fees and a lack of transparency about where ads were actually running.

Let that sink in for a moment.

OpenPath wasn't some scrappy startup's experimental feature. It was The Trade Desk's flagship Supply Path Optimization initiative. Jeff Green himself bullishly anticipated 2025 as the year it would enter the "steep acceleration phase of its S-curved growth." It was supposed to help advertisers "directly purchase publishers' inventory" with better performance and cleaner supply paths.

And yet, the industry's most sophisticated buyers walked away because they couldn't get basic answers: Where are our ads running? What are we actually paying?

How is this possible despite TTD putting its full weight behind OpenPath?

The answer lies within the infrastructure itself.

Why Programmatic Infrastructure Doesn't Fit CTV

Here's the context the industry keeps missing: programmatic infrastructure was built for a specific problem - fragmented digital display inventory scattered across millions of websites.

In that world, you need DSPs to aggregate demand and SSPs to aggregate supply. You need exchanges to match buyers and sellers. You need layers of optimization because the supply is so fragmented and variable.

CTV is different. 

Roughly 90% of CTV impressions come from about just 10 publishers. Supply is highly concentrated among premium streaming platforms. These aren't millions of fragmented websites; these are major publishers like Disney+, Hulu, Peacock, Paramount+, HBO, Netflix, and a handful of others.

When supply is this concentrated, intermediary infrastructure doesn't add value. It adds cost and opacity.  What most people don’t realize is that OpenPath is just disguised programmatic technology (i.e. a header bidding solution) for CTV. It comes with the same issues and concerns that forced Dentsu and WPP to question their reliance on TTD’s platform. To be fair, it’s not bad tech; it’s just that the model is fundamentally flawed for the structure of the CTV ad market.

Is There a Solution? (Spoiler Alert: Yes.)

The Trade Desk will undoubtedly address the concerns and promise a swift resolution, maybe even Dentsu and WPP will return?

But that misses the bigger point - and does not address the fundamental problem.

The industry built programmatic for a fragmented digital ecosystem. CTV is not fragmented. Its premium supply is concentrated among a small group of major publishers.

The next phase of CTV buying will be defined by something simpler: removing the paths that don’t need to exist.

We built it. It's live. And we call it Upstream. And the publishers representing the majority of premium CTV inventory - Disney, NBCUniversal, Paramount+, Warner Bros. Discovery, and Tubi - are already using it. While everyone else optimizes downstream, we moved upstream.

Read more about how Upstream is bringing transparency to the world of CTV media buying.