By Publicis Groupe told clients on March 17 to stop using The Trade Desk. The holding company said an independent auditor found hidden fees, unauthorized feature activations, and billing that didn't match the master agreement. The Trade Desk's CEO Jeff Green fired back on LinkedIn, defending his company's transparency record and taking a shot at agencies who "want to wave the flag of transparency publicly but run from it in practice as they arbitrage in the inefficiencies of programmatic."
That was ten days ago. Since then, Omnicom has commissioned its own third-party audit, reportedly with a Big Four accounting firm. WPP and Dentsu had already quietly dropped The Trade Desk's OpenPath product over similar concerns about opaque fees. Four of the five largest agency holding companies are now either auditing, distancing from, or actively steering clients away from the dominant independent DSP.
If you've covered this industry long enough, you've seen this movie before. The last time the ad business had a real transparency reckoning was the ANA's 2016 media transparency report, which documented rebates, kickbacks, and undisclosed markups that agencies swore didn't exist until they did. A decade later, here we are again, except this time the fight is between agencies and the platform that was supposed to be the transparent alternative.
What the audits actually found
Publicis hired FirmDecisions to audit The Trade Desk's billing against their master agreement. According to Publicis's statement to MediaPost, "an experienced independent auditor concluded that The Trade Desk did not pass the audit." The specific allegations include fees applied to services the holding company never approved, and clients enrolled in tools without consent.
The Trade Desk flatly denies failing any audit. The company says Publicis requested data that "would violate customer and partner confidentiality agreements" and offered alternatives, including "information at an even more granular level than requested." TTD also took a swipe at FirmDecisions, suggesting it wasn't among the most widely recognized audit firms, a point that clearly stung when Omnicom announced it would use a Big Four firm for its own review.
Omnicom told clients its initial contractual review "did not identify any negative impact" from its Trade Desk dealings. But it's still sending in the auditors. That's the corporate equivalent of saying "we're fine" while hiring a lawyer.
Meanwhile, WPP and Dentsu had already exited OpenPath, TTD's supply chain optimization product, over the same kind of fee visibility concerns. According to Level Agency, the allegations across all four holding companies include "fees misapplied across line items, tools activated without client approval, audit results that couldn't be verified."
Follow the money
Here's where the transparency framing starts to feel like a convenient cover story for something bigger.
According to Morningstar, just two agency holding companies accounted for 30% of roughly $13.4 billion in gross spending on The Trade Desk's platform in 2025. That's an enormous amount of leverage, and the agencies know it. Morningstar cut TTD's fair value estimate from $33 to $29 per share, modeling a 10% exodus of agency budgets to competing DSPs.
The Trade Desk posted $2.9 billion in revenue in 2025 with 47% margins. Those are very good margins for a company whose biggest customers are publicly threatening to leave. Multiple sources described to Digiday an internal "obsession" at TTD with protecting margin levels, even during high-growth periods.
And here's the detail that explains more than any audit finding: TTD has been increasingly pitching directly to brands, creating joint business plans that can command higher rates than agency-negotiated terms. As Digiday reported, this "effectively bypasses the benefits of aggregated agency spend." A former TTD insider described the company's formalized relationship with Publicis as "a kind of, like, a deal with the devil," given TTD's public championing of transparency.
The agencies aren't just upset about fees. They're upset that the platform they built their programmatic buying around is now going around them to their own clients.
The real fight: margin and control
Jay Friedman, a longtime agency executive, told Digiday what anyone who's worked agency-side already knows: "We're all familiar with the school of thought, or the rationale that basically agencies are getting so beaten up by their clients, procurement departments, when it comes to margins, they have to get money from somewhere."
That "somewhere" has traditionally been the programmatic supply chain. The ISBA/PwC study in 2020 found that 15% of advertiser spend in programmatic was completely unattributable, meaning nobody in the chain could explain where it went. Agencies and platforms both benefited from that fog.
Now TTD is building products like OpenPath, identity frameworks, and algorithmic optimization systems that shift control to the platform layer. That's good for TTD's margins. It's potentially good for advertisers who want a more direct path to inventory. It is very bad for agencies who've built their economics around being the indispensable intermediary.
Green's LinkedIn post was revealing. He wasn't just defending TTD. He was going after principal-based buying, the practice where agencies buy inventory and resell it to clients at a markup. That's a direct shot at how several holding companies have restructured their media businesses to maintain profitability. When Green wrote that some industry leaders "advocate for moving dollars to more opaque platforms and transaction methods," he wasn't being subtle.
What's next
The Omnicom audit will be the one to watch. If a Big Four firm finds the same issues FirmDecisions reported, TTD has a real problem. If it comes back clean, Publicis's position gets harder to defend.
Advertisers are already looking for alternatives. Tom Wigley of VCCP Media UK told Digiday that Amazon DSP is "front and center" due to its retail media and Prime Video combination. Tucker Matheson of Markacy said his firm has moved spend toward direct buys and retail media networks "where measurement is cleaner."
TTD CMO Ian Colley offered a statement that read like it was written before any of this happened: "The Trade Desk has always believed that a healthy, competitive marketplace is optimal for brands, so we welcome competition from companies of all sizes."
This is what it looks like when the economics of an industry get renegotiated in public. The agencies are fighting to stay relevant as intermediaries. TTD is fighting to expand beyond execution into a platform that owns the full transaction. Both sides are framing their financial interests as transparency advocacy, which is the oldest move in the holding company playbook.
The advertisers, as usual, are the ones writing the checks and getting the least information about where the money actually goes.
Zach El-Amin covers ad tech for The Daily Vibe.
