The past few weeks have produced one of the more theatrical transparency disputes in programmatic advertising’s history. Three of the big six holding companies have either exited or are auditing The Trade Desk. The dominant independent DSP’s stock is down roughly a third in 2026. And everyone involved is claiming, with varying degrees of conviction, to be acting in the client’s interest.
A cynic might note that transparency has always been this industry’s most useful weapon — deployed selectively, against whoever currently threatens your position in the chain. In the end, the only thing the supply chain agrees on is that someone else should open their books first.
The setup
In February, WPP and Dentsu exited OpenPath, The Trade Desk’s direct-to-publisher initiative. The stated concerns were fee visibility and placement clarity. The unstated concern — widely understood — was that OpenPath routes around agency trading desks, compressing the margin agencies extract from supply-path optimisation.
Then in mid-March, Publicis sent a memo to select clients advising them to stop using The Trade Desk. The company commissioned FirmDecisions, a media specialist auditor within the Ebiquity Group, to review The Trade Desk’s fee structures. According to Publicis’s account of what the audit found, The Trade Desk had improperly applied its DSP fee to other charges and billed clients for tools they’d been enrolled in without evidence of authorization. The Trade Desk disputed Publicis’s characterization — FirmDecisions declined to comment publicly — and said the data requested would have violated confidentiality agreements with other clients and partners. This week, Omnicom announced its own audit, reportedly conducted by KPMG, after an initial internal review found no issues.
Observers called it a transparency dispute. Our reporting suggests it’s a control one.
What’s actually happening
One senior industry source with direct experience of how these relationships operate pushed back on the more dramatic readings. “I don’t think any of this is a big deal,” they said. “It’s the marketer who decides on the platform. It’s not the agency that says we’re going to use The Trade Desk. It’s that brand X says ‘The Trade Desk is our buying system of record’.”
That’s the structural reality the discourse keeps obscuring. The Trade Desk disclosed in 2025 that joint service agreements — direct contracts with advertisers that bypass the agency master services agreement structure — account for more than 60% of its revenue. Needham estimates that 70% of Publicis’s brand clients have direct deals with The Trade Desk, meaning Publicis’s recommendation is incapable of moving most of that spend. The real revenue at risk is roughly $87 million against a $2.9 billion base. And even that number overstates Publicis’s leverage, because many of those contracts aren’t really with Publicis — they’re with Publicis clients. The agency executes. The marketer decides.
The same source reframed the OpenPath exits and audit pressure as being less about extracting margin from vendors and more about maintaining client proximity.
“It’s not necessarily about more margin. It’s about how they can maintain closer ties to the client,” they said. The Trade Desk’s real commercial offense, in their reading, isn’t fee irregularities — it’s having been “very savvy with the commercials” in ways that pull the brand relationship toward the platform and away from the agency.
That doesn’t make the fee allegations irrelevant. But it does reframe what the audit actually is: less a coordinated strategic offensive than a blunt instrument grabbed by organizations that have already lost the commercial ground they’re nominally defending, said the source.
The strategy and the frustration aren’t mutually exclusive. They rarely are.
What The Trade Desk’s defense reveals
The Trade Desk’s response followed a clear sequence: dispute the findings, attack the auditor’s credibility, invoke confidentiality. The confidentiality argument is the most telling part. The Trade Desk said it couldn’t share certain data because doing so would expose its agreements with other holdcos — meaning different holding companies may be on materially different commercial terms, and The Trade Desk is using confidentiality to protect that. It’s not a novel defense. It’s what holdcos say when advertisers ask about principal media margins.
That’s worth sitting with. The companies currently auditing The Trade Desk’s fee structures are the same ones CEO Jeff Green was describing on The Trade Desk’s full-year 2025 earnings call when he said some agencies “wave the flag of transparency publicly but run from it in practice.” Court documents from the Foster v. WPP litigation show GroupM recorded more than $1 billion in what WPP calls “non-product related income” — its term for principal media revenue — in 2023. Nobody commissioned an independent audit of that.
What nobody is parsing
Two years ago, IPG, WPP and Omnicom all took modest equity stakes in MediaOcean — $20-25 million apiece, according to AdAge — as part of a new certified service partner programme. At the time it got minimal coverage. In retrospect it looks like something else: three of the companies now auditing or distancing themselves from The Trade Desk investing in the infrastructure layer that sits beneath it.
“Any platform or service provider that attempts to get between a publisher/media and client marketer is a threat to the three big holdcos,” said Steve Boehler, founder of agency and marketing consultancy Mercer Island Group. “The Trade Desk continued to succeed where the agency trading desks failed. This threat could not continue unabated. The three giant holdcos each seem to want to rebuild their digital trading desks — and The Trading Desk tax — back to 2016 and prior levels. The holdcos can’t really control the giant walled garden media, so continuing to lose control of the open web may have been perceived as a bridge too far.”
The bridge, it turns out, was always theirs to burn.
—Jess Davies contributed to the reporting of this article.
Numbers to know
70%: Percentage by which OpenAI’s AI-content app Sora downloads plummeted in March 2026, per Similarweb.
3: Number of hours it took users on Snapchat to post more Snaps than the total number of songs on Spotify.
500: Total number of subscribers a YouTube creator needs to have to access YouTube Shopping affiliate program, now the company has lowered the barrier to entry.
90%: Percentage of people surveyed for Sprout Social’s Q1 Pulse Survey said AI generated content has eroded trust in social media news.
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