- Publicis Groupe’s win of Mars’ $1.7B media account marks its third major takeover from WPP in 2025.
- WPP’s counterpunch? A public accusation claiming Publicis’s Epsilon is filling the ad ecosystem with low-quality, MFA inventory.
- WPP’s research shows 26% of test impressions were served on spammy, low-engagement websites.
- Amid leadership transitions and client churn, WPP is shifting the narrative to ad quality and transparency.
- This feud reveals escalating tensions between scale, accountability, and the future of programmatic media.
With Mars and Coca-Cola lost to Publicis, WPP is hitting back, accusing its rival of flooding the market with junk inventory.
In a battle that’s quickly escalating from quiet rivalry to corporate war, two of the world’s largest advertising holding companies—Publicis Groupe and WPP—are now locked in a high-stakes feud.
At the heart of it: billions in lost accounts, a rapidly shifting digital landscape, and mounting accusations of bad-faith media practices.
Publicis Lands Mars After Snatching Coca-Cola
The spark? Publicis’ back-to-back wins of two of WPP’s most prized media accounts: Coca-Cola North America and, most recently, Mars’ global media business. Together, those accounts represent over $2.4 billion in annual media spend.
Mars handed its $1.7 billion global media account to Publicis after a competitive six-month review involving all major holding companies. The French powerhouse will oversee media buying, commerce, paid social, influencer marketing, and production in more than 70 markets.
The move expands Publicis' footprint with Mars, building on its September 2024 acquisition of Mars United Commerce, which already handled the brand’s commerce marketing.
WPP, long the incumbent via EssenceMediacom, has now lost three marquee clients this year alone—Coca-Cola, Paramount, and Mars—at a time when the agency giant is struggling with declining revenues and the announced departure of CEO Mark Read.
Publicis, by contrast, is surging. Its Power of One model, AI-led transformation efforts, and aggressive acquisition strategy have helped it capitalize on key account reviews. The Mars win is widely seen as validation of that model.
WPP Strikes Back with Harsh Accusations
But WPP is not taking the losses quietly.
In a rare and unusually public attack, WPP has circulated an "intelligence report" to clients, accusing Publicis of undermining media quality standards through Epsilon’s programmatic supply-side platform, Conversant.
The report alleges that Epsilon floods the digital ad ecosystem with low-quality, low-viewability inventory—much of it classified as "made-for-advertising" (MFA) content. According to WPP’s internal test, 26% of 500,000 impressions purchased through Publicis-linked inventory came from MFA sites, and 25% originated from a retail media site under Publicis' CitrusAd network, with a viewability rate of just 2%.
The report, shared with client leads and leaked to the press, marks a stark departure from the industry’s usual behind-the-scenes jostling. WPP’s aim is clear: cast doubt on the integrity of Publicis’ data-driven platforms at a time when brands are demanding transparency and measurable quality from their media buys.
Adding fuel to the fire is a rumored yet unreleased Adalytics report that allegedly echoes WPP's findings about the poor quality of Epsilon’s inventory.
Industry Reactions: A PR Win or Misfire for WPP?
WPP’s decision to go public with its accusations against Publicis’ Epsilon platform drew swift, sharp, and at times humorous responses from the marketing and media community.
While some acknowledged the legitimacy of concerns about inventory quality, the broader reaction was clear: WPP’s move may have backfired in the court of public opinion.
The tone across LinkedIn was split between industry weariness and outright mockery. Some marketers, like Mari Docter, summed it up in a viral quip: “The girls are fighting.” Others, including Brendan Kennedy, suggested the drama had reached meme-worthy levels: “They gotta release a diss track.”
But behind the humor was a pointed critique.
Quentin P., a seasoned brand and performance marketer and CMO of Creation Collective, questioned WPP’s judgment in launching the attack so soon after its leadership reshuffle:
Steve Parker Jr., Chief Client Experience Officer at Mindgruve, took a broader industry view, condemning both players:
Others were more matter-of-fact. A user echoed the sentiment that these types of accusations weren’t shocking to insiders. And another reinforced the critique of Epsilon’s inventory:
Yet even this acknowledgment came with skepticism over WPP’s intent. Marvin Duval, a Group Strategy Director, put it bluntly:
In short, the sentiment among marketers and media professionals is largely dismissive of WPP’s strategic value in going public. While Epsilon’s quality issues may have some basis in fact, WPP’s approach has been interpreted as a defensive maneuver, rooted more in damage control than in client advocacy.
Verdict: WPP’s public swipe has not helped its case.
The reaction reveals deep cynicism toward both agency giants, but particularly positions WPP as reactive and unfocused during a critical period of transition. Publicis may not walk away unscathed, but the narrative—at least for now—is that WPP’s strategy risks doing more reputational harm than good.
A War on Two Fronts: Business and Reputation
The stakes of this feud go beyond Mars and Coca-Cola. For WPP, it’s about defending its relevance amid financial setbacks and executive turnover. For Publicis, it’s about maintaining momentum and proving that its AI-powered, integrated offering isn’t just efficient, but ethical.
There’s also a broader industry context: brands are reevaluating their media ecosystems in light of growing scrutiny over ad fraud, MFA content, and opaque programmatic supply chains. Holding companies that can’t demonstrate inventory quality and control risk losing not just accounts, but long-term trust.
WPP’s public critique appears to be a reputational countermove—one designed to stall Publicis’ momentum and signal to the market that scale without scrutiny is a liability. Whether it works remains to be seen. But the campaign marks a turning point: the gloves are off, and the industry is watching.
