In a rare and direct confrontation between global advertising giants, WPP has openly criticised rival Publicis Groupe, accusing its Epsilon-operated supply-side platform (SSP) of distributing low-quality digital ad inventory that fails to meet industry benchmarks for viewability and user attention.
The accusations are detailed in a new 'intelligence report' compiled by WPP Media, which was initially shared internally with client leads before being selectively distributed to brands. The report alleges that Epsilon’s inventory — delivered primarily through its Conversant SSP — includes a significant volume of ‘made-for-advertising’ (MFA) sites and inventory sourced from questionable supply paths.
According to reporting by Ad Age, WPP ran a programmatic media buying test using its own budget across two days in May. Of 500,000 impressions purchased, 26% reportedly came from MFA sites — web pages designed primarily to maximise advertising impressions rather than user engagement. Additionally, a quarter of the inventory was served via a retail media site within the Publicis-owned CitrusAd network, where viewability averaged just 2%.
This public rebuke comes as the competition among holding companies intensifies, with transparency, media quality, and performance metrics under increasing scrutiny from brands. The report’s release follows over a year of private client briefings by WPP CEO Mark Read, who had previously voiced concerns about Epsilon’s supply practices and opaque inventory sources, some of which echo findings from a yet-to-be-released Adalytics investigation.
WPP’s attack underscores growing tensions in the media buying ecosystem, particularly as advertisers demand greater accountability in programmatic channels. It also signals heightened rivalry between the two firms, especially after Publicis recently snatched Coca-Cola’s North American media account from WPP and is now in contention for Mars’ global business.
The report’s timing is notable, coming amid uncertainty at WPP as it grapples with slower organic growth compared to peers and faces potential upheaval from the proposed Omnicom-IPG merger. CEO Mark Read’s expected departure later this year adds another layer of instability.
Publicis, on the other hand, appears to be gaining ground, with its Epsilon and CitrusAd units central to its data-driven media strategy. Whether the allegations will damage its momentum remains to be seen, but the gloves are clearly off as agency groups fight for dominance in an increasingly cutthroat market.
