Seven things you need to know about the ex-WPP whistleblower’s latest legal filing
A legal filing by a former WPP executive claims an independent investigation by one of WPP’s largest global clients, Sony, corroborates his allegations of illegal business practices by the holding group and its media-buying arm, GroupM (now WPP Media).
Lawyers for the claimant, Richard Foster, the former global chief executive of WPP’s Motion Content Group, write that GroupM and WPP “knowingly benefited from practices that violated their legal obligations to their clients and violated the law”, asserting that “when those practices came under scrutiny from advertisers, [they] did not abandon them. Instead, they obscured them while preserving the underlying business model and illegal practices.”
Foster, who claims he challenged such practices internally for nearly a decade, says he was “marginalised, ostracised, and eventually forced out” for doing so. He is suing for wrongful termination and retaliation.
Foster is seeking punitive damages of at least $100m from WPP, as well as compensatory damages and statutory and civil penalties for the holding group.
The latest legal filing, an amended complaint, came ahead of a hearing on WPP’s motion to dismiss the case. A spokesperson for WPP told The Media Leader: “This amended complaint, filed just prior to the hearing, is an attempt to avoid its dismissal. Both complaints are baseless and without merit, and WPP will be re-filing an updated motion to dismiss. We have confidence that this matter will be resolved through due legal process.”
Here are seven of Foster’s most notable claims.
1. Sony conducted an independent investigation and reached the same conclusions over proprietary media
Foster, a 17-year veteran of WPP’s media buying arm, filed the lawsuit against WPP in November 2025. In a subsequent 35-page filing in March, Foster made public more than $9bn worth of client adspend data.
At the crux of his allegations is that WPP and GroupM routinely failed to act in their clients’ best interests by engaging in deceptive proprietary media trading practices, even in markets where doing so is illegal. The practice — whereby an agency purchases ad inventory from a media owner and resells it to clients at a mark-up — is controversial among brand marketers, agency leaders and industry trade bodies.
The main new material in the latest filing is evidence that Sony, WPP’s then fifteenth-largest global client, conducted its own independent investigation into WPP’s practices and reached a conclusion similar to Foster’s about the holding group’s trading model.
The filing alleges the investigation was spurned by a scandal in which WPP executives in China were found to have taken kickbacks totalling $176m from broker firms in exchange for offering them some of WPP’s ad-placing business.
It also alleges that WPP’s general counsel of media, Nicola McCormick, who had been appointed to lead an effort to “clean up” the company’s proprietary media scheme, told Foster it was her view “that the problem was not confined to China” but rather was “symptomatic of a global problem.”
Investigators for Sony allegedly attended the criminal trial in China and probed several former WPP and GroupM executives about the company’s proprietary media scheme. In December 2025, the filing claims Sony confronted WPP executives about the scheme in WPP’s Japan offices.
At the meeting, Sony allegedly explained, using several charts presented in the legal filing, that WPP “deliberately designed a broker model in China to function as a financial warehouse to hold rebates for later utilisation”.
The primary mechanism for distributing those rebates, Sony allegedly found, is proprietary media, “wherein the purported ‘discount’ WPP offers clients on inventory is manipulated: WPP pays a fraction of the out-of-pocket cost to acquire the inventory, subsidises the remaining balance using funds from the rebate pool, and pockets the resulting margin as near pure profit shielded from audits”.
The filing claims Sony found WPP wrongly retained $350m in its rebate pool in China in 2024, passing just $110m on to clients. It also claims Andrew Meaden, GroupM’s then global head of investment (now WPP Media’s global chief investment officer), oversaw the scheme and “set KPIs, monitored the model’s execution, and dictated profit conversions”.
The scheme, Sony concluded, “proliferated across other markets”, not just China, “serving as a lever to artificially inflate earnings at WPP.”
2. Meta and other media owners could have been punished for opting out of proprietary media deals
The lawsuit claims that, during a meeting in 2023, Meaden proposed “re-routing” client spend away from Meta after Meta refused to enter into a proprietary media deal with GroupM.
Foster claims he objected, noting it would be illegal for GroupM to coerce vendors into such an agreement by threatening to withhold clients’ adspend.
In response, Foster says Meaden cut him out of future workstreams related to Meta and other initiatives in North America.
According to the filing, such behaviour was standard practice. GroupM’s trading operation, Foster alleges, “pooled client spend to pressure vendors into providing heavily discounted inventory that GroupM could reclassify as proprietary media and resell to clients. Vendors that complied were rewarded with client spend; those that refused were penalised by the redirection of those budgets to other outlets.”
This allegedly occurred even as “a significant portion of GroupM’s largest clients”—roughly 62%, including Coca-Cola, Unilever, Amazon and Adidas—declined to opt in to proprietary media agreements as of late 2024.
And yet, Foster claims, those clients’ spending was, without permission, “still leveraged to generate the same vendor-funded inventory pool”, even though “they could not access that inventory.”
The filing continues: “This allowed GroupM to retain, repackage, and monetise the inventory elsewhere rather than credit that economic value back to the clients whose spend produced it, all while maintaining a public posture of ‘100% transparency'”.
The lawsuit claims the practice was institutionalised with benchmarks. “Extraction rates” were allegedly created to measure how much proprietary media a media owner secured relative to client spend. “These metrics, along with net sales growth targets derived from rebate deals, became performance benchmarks for local chief investment officers globally,” the filing claims, with such metrics impacting the compensation and job security of chief investment officers.
Foster claims local trading teams would leverage client spend in negotiations with vendors to extract rebates for the agency. Local traders would then allegedly record those deals as proprietary media in a “centralised deal-management system” that obtained approval from regional trading and finance directors. Deals over a certain amount also required sign-off from the global chief finance officer of both GroupM and WPP. However, the filing claims legal and compliance teams were not part of this process.
Foster further claims he learned that, in order to evade auditor scrutiny, “Margin caps were implemented so ‘deal margins’ appeared more in line with ordinary margins” and that “local ‘silos’ were maintained, ensuring that auditors conducting reviews would be unlikely to detect rebates undisclosed within isolated markets.”
3. Principal media a crutch for WPP
The legal filing argues that Foster and others’ internal efforts to push back on such practices and “clean up” WPP’s business routinely conflicted with “pressure to prop up WPP’s bottom line”, particularly as the company lost major clients and its financials worsened in recent years.
According to the filing, WPP’s principal media scheme accounted for “over half of its publicly reported profits”, had become “integral to WPP’s financial survival”, and, as a result, “WPP could not come clean without facing financial ruin.”
Foster calculates that GroupM generated between $3bn and $4bn in the scheme over the past five years, of which $1.5bn to $2bn was “improperly retained profits”. Leadership, he says, instituted targets to scale the practice by 15% year-on-year.
Foster argues leadership disincentivised internal dissent. The filing reads: “Insiders within GroupM understood that those who questioned the propriety of the Rebate scheme would be the object of adverse action by [then-GroupM chief operating officer Mark] Patterson and Meaden.”
4. Report on illegality of trading practices was given to Brian Lesser
At the centre of Foster’s allegations is that WPP personally marginalised him and eventually fired him because he raised concerns about proprietary media trading practices with senior management. Foster was made redundant in July 2025, following the sweeping reorganisation of GroupM into WPP Media.
In July 2024, WPP hired Brian Lesser as CEO of GroupM, replacing Christian Juhl. As part of the leadership turnover, then-WPP CEO Mark Read allegedly instructed Foster to meet with Lesser to align on creating a new entertainment division that Foster would lead. Lesser and Foster met, and during the briefing, Foster raised concerns about WPP Media’s proprietary trading.
Following the meeting, in December 2024, Foster submitted a confidential report to Lesser outlining his vision for the new division and concerns about the trading practices under the leadership of both Patterson and Meaden. Citing contemporaneous communication between Foster and McCormick, the filing states Foster “explicitly feared retaliation” from Patterson or Meaden for doing so.
Foster’s report allegedly included a 2024 net sales breakdown that attributed $713m to “trading inventory” by reclassifying free or discounted vendor inventory as proprietary media under what was known as the “GroupM flex” framework.
The filing claims Lesser initially reacted to Foster by stating “his concern over the risks associated with the ‘legal issues’ raised in the report” and apparently committing to handle further action.
However, on 21 January 2025, Lesser contacted Foster and asked him to prepare a “sanitised” version of the report to share with Patterson that omitted “any overt criticism of [GroupM] trading as that is not in the spirit of working together.”
Foster claims Lesser also forwarded his original report to Patterson, who subsequently iced him out of developing WPP’s new entertainment division.
“Hey. So it looks like I’ve been screwed by Brian [Lesser],” Foster wrote McCormick.
Not dealing in principal media costs us millions, but keeps us impartial – the7stars
5. Internal investigations found GroupM maintained conflicting versions of contracts with vendors
In early 2025, around the same time as Foster was allegedly asked to submit the “sanitised” version of his report, GroupM began rolling out a new media investment policy, led by McCormick, Meaden and Carlos Catalan González, GroupM’s global CFO of investment.
The filing claims that, as part of that rollout, representatives from GroupM’s trading and legal teams were dispatched to explain the policy change to local offices and inquire about “trading income” issues. The outreach allegedly uncovered “numerous rebate-related issues across multiple regions”, triggering additional internal investigations that concluded GroupM “improperly retained rebates and other benefits tied to client spend.”
The filing claims that in one instance, an internal investigation found that GroupM “maintained two conflicting versions of a contract with a single vendor: a sanitised client version that misrepresented the rebates, and a hidden internal version outlining the actual rebates”. This set-up, the filing argues, allowed GroupM to “illegally retain the difference.”
6. Foster declined ‘seven-figure payment package’ in return for his silence
Foster says he was offered a “seven-figure termination package” when the company let him go in 2025. The package, he claims, included “an obligation of silence regarding the Company’s undisclosed rebate practices”. He refused the package and instead chose to file suit.
The Media Leader understands that WPP routinely asks employees it has made redundant to keep silent about company matters, but does not formally require non-disclosure agreements (NDAs) as part of settlement agreements.
7. Class action suit allegedly corroborates Foster
Nick Manning, co-founder of media agency Manning Gottlieb (now Omnicom agency MG OMD), columnist for The Media Leader, long-standing critic of proprietary media trading and an advisor to Foster’s legal case, told The Media Leader the latest court filings “are the most revealing yet on the alleged ‘inner wiring’ of the media agency industry.”
He added: “The trust between an agency group and its clients cannot hold in such circumstances, and the amount of concealment reported by the papers lays bare the extent to which WPP’s media agencies were potentially compromised.”
Manning noted that a further class action lawsuit filed in the Southern District of New York, brought by institutional investors, has alleged WPP misled investors about the strength of its business.
World of pain? Further evidence that principal media is harming the ad industry
Foster’s latest legal filing references the other suit, which it notes names WPP Media CEO Brian Lesser as “a defendant responsible for material misstatements and omissions”, and includes interviews with former WPP executives that allegedly corroborate Foster’s account.
The class action lawsuit “also alleged principal/proprietary double- (and sometimes triple-) dipping that they witnessed first-hand and had to execute,” Manning describes. “The sad reality is that many media agency people have to tread a fine line between their obligations to their clients and their duties to their employers. Trust is the victim.”
Manning advocates “clean” fees that require all trading benefits to be returned to clients.