CTV’s reseller reckoning, moving past scale on paper, confusion in practice

Traditionally, those answers came from the buy side – the demand-side platforms. Now, more buyers are pressing the sell-side instead. 

“With the commercial deals we have with advertisers, we’re starting to see more demands over the transparency and the provenance of the inventory we’re selling,” said Tyler Romasco, svp of global publisher development at OpenX. 

Case in point: this summer, OpenX struck a deal with a major holdco, giving two of its advertisers direct access to its CTV inventory in the U.S. One of the selling points was the fact that it had no resellers. Just a cleaner, more accountable supply chain. And more deals like this could be coming. Over the course of the summer, Romasco sat down with 40 buyers to hash out transparency in CTV, with a focus on resellers.

Granted, cutting out resellers doesn’t fix everything. But it does get to the root of CTV’s visibility problem: too many hands in the pot, and too little insight into who’s actually selling what to whom. Resellers, fairly or not, are a microcosm of that: they’re intermediaries who don’t own the content or the app it runs on but still claim the right to sell the inventory. Sometimes that access is legitimate. Sometimes it isn’t. Either way, the result is the same: scale on paper, confusion in practice. 

And the scale of that confusion is increasingly measurable. 

Over the past three months, the number of U.S. streaming devices available through direct sources like app developers, content owners, OEMs, and well-operated ad networks has hovered steady around 125 million per month, according to Jounce Media. But outside those trusted pipes, tens of millions of additional devices are appearing in the bidstream through ad networks that are reselling inventory from other networks. That’s where problems arise: when inventory is resold multiple times, it becomes harder to trace its origin — and some it may not even be coming from real CTV devices at all. 

Jounce’s conclusion is blunt: there are two types of resold CTV auctions at play here — the ones that waste 20% of a marketer’s budget and the ones that waste 100%. At best, resold inventory injects unnecessary fees into the supply chain. At worst, it introduces completely fabricated inventory. 

“We are moving more towards operating seats within SSPs and the ad servers themselves that are plugged into the CTV inventory, which means that we can connect to publisher inventory directly,” said Maikel O’Hanlon, svp and managing director of programmatic at Horizon Media. 

It’s a pattern ad tech veterans know well. Anytime advertisers have become nervous about what they’re buying — whether it was around take rates or made-for-arbitrage sites – they get closer to SSPs like Openx to allay those concerns. Because being inside the SSP or ad server lets buyers trace exactly where an impression originates – what app it ran on, who sold it and whether it actually appeared where it was meant to. It’s the difference between buying inventory and understanding it. 

As O’Hanlon explained: “We have so much more line of sight into the actual supply that is coming our way when we are spinning up [CTV] deals and pushing them out to then be bought by our clients, as opposed to having those deals be curated either by the pubs themselves or an SSP.”

It’s taken time, but OpenX’s 2023 decision to cut resellers out of its marketplace is starting to look prescient. As Romasco put it: “We weren’t sure it was going to impact our revenue but we believed it was the right thing to do for the market, having seen what happened on the web and in-app with reselling.”

The bet is starting to pay off thanks to a few converging forces: rising buyer scrutiny due to bigger budgets, the measurable cost of murky inventory and a broader reckoning with how CTV is bought and sold. The result is more marketers, from Coca-Cola to Mars, no longer satisfied with scale for scale’s sake in CTV. They want provenance, accountability and fewer intermediaries muddying the water.  

“We’re not going through any resellers or any other exchanges in terms of what we’re buying for our clients,” said Nick Halas, head of commercial solutions at Dentsu’s media investment arm at Amplifi Global. 

Unlike traditional programmatic setups, where the buyer puts money into a programmatic marketplace and hopes to make sense of the reporting later, this deal gives Dentsu’s EMEA traders full visibility into the supply chain. They decide how inventory is sourced, who touches it and ultimately where the ad dollars end up. 

“We can do that as we’ve actually set ourselves up to be a legal entity and a seat within the Magnite platform,” said Halas. “We now control the contractual – and therefore the legal – relationship with the publisher.”

In practice, that lets Dentsu curate supply on behalf of clients, then package it into deals that can run through any preferred tech stack – whether that’s a demand-side platform like The Trade Desk or Magnite’s own ClearLine. For resellers, that makes survival harder by the day. 

“They both do one of the same things, although you could technically argue that the ClearLine solution in certain situations does allow more spending on working medium, less on tax,” said Halas. 

That tax point is a quiet undercurrent in CTV right now. As much as these choices are motivated by transparency, they’re also about economics. Resellers are being recast as a drag on both: difficult to trace, expensive to justify and easier than ever to cut. 

“The investment levels around CTV is bringing accountability into the space,” said Horizon Media’s O’Hanlon.

It was ever thus. CTV is just the latest in a long line of line items on a media plan to get that discerning look from marketers. 

“There is a definite increase in agencies and buyers looking to understand the provenance of their CTV advertising in 2025,” said James Grant, svp of advanced television at CTV ad tech firm Equativ. “We see a focus on direct supply, also on 2-node (via primary SSP) for aggregated Premium CTV supply from all buyers.”

None of this means all resellers are bad. Many still provide the reach advertisers want and the additional demand publishers need. Which is why Magnite and TripleLift still work with a few carefully selected ones unless advertisers advise otherwise.

But in today’s CTV market, the burden of proof has shifted. Resellers are no longer assumed. They have to be justified.