Sony used the contact form.

For a month, WPP has told a New York judge that Richard Foster's lawyers must have gotten Sony's internal investigation of WPP's rebate practices through the back door. Sony's silence and Foster's refusal to name his source, WPP's sealing motion argued, "strongly indicates that he obtained the information by improper means." The company then asked the court to sanction Foster, dismiss his lawsuit with prejudice, remove his law firm from the case and force him to name his source.

Late Wednesday night, Foster's side named it. Sony.

According to affirmations filed September 9 in New York State Supreme Court, a representative of Sony Group Corporation submitted an inquiry through the "Contact Us" form on the public website of Brewer, Attorneys & Counselors on February 26, 2026. Three months later, Sony asked for a meeting. On May 19, "a team of Sony representatives" presented to Foster's counsel over a remote call. The filing says Sony "voluntarily provided information regarding Sony's investigation of acts and practices by Defendant WPP, PLC."

"Sony did not request that any aspect of their presentation of the materials provided be held in confidence," the affirmation states.

A client of the defendant, walking its own findings over to the plaintiff's lawyers, uninvited. That is not how leaks usually work.

The account comes in two sworn statements from Brewer staff.

Ryan Condon, the firm's administrator, runs its intake. He swears that submissions through the website form are "logged with a timestamp" and routed to a mailbox he monitors. On February 26, "a representative of Sony Group Corporation submitted an inquiry through the Contact Form."

"The submission was unsolicited," Condon wrote. "Neither I nor anyone else at the Firm requested, invited, or otherwise solicited contact from Sony Group Corporation or any of its representatives concerning this litigation."

Xinni Zhang, the firm's chief of staff, picks up the thread. After that first contact, she swears, Sony requested the meeting on May 18 and it took place the next day. She also swears that paragraphs 136 through 148 of Foster's amended complaint, and the six figures that go with them, "reflect the information provided to the Firm by Sony."

Those are the paragraphs WPP has spent a month trying to get off the public docket. According to the amended complaint, Sony's review found that WPP returned about $110 million in rebates to clients in China while retaining roughly $350 million.

WPP's case against Foster's sourcing has never rested on evidence from Sony. It rests on inference, and WPP's own paperwork says so.

In an August 17 demand letter, WPP's lawyers wrote that as to the Sony material, they "are continuing to investigate and are not making a definitive accusation as to source at this time." The same letter, according to Foster's brief, reserved the right to pursue "criminal prosecution."

The sworn support WPP later filed came from WPP Media chief executive Brian Lesser, not from Sony. His affirmation says Sony "has not publicly disclosed that information and, to my knowledge, has not authorized" anyone to disclose it.

To my knowledge.

Foster's lawyers noticed. "Nothing from Sony," their brief says. "The omission is telling."

Then there is what WPP told the judge about the meetings where Sony presented its findings to WPP. In an August 18 email to Justice Andrew Borrok, WPP's counsel wrote that those meetings "were conducted in confidence and the substance of which was never disseminated beyond the attendees of those meetings."

By WPP's own account, the only people who knew what Sony found were the people in the room. Foster's filings now say Sony carried it out of the room itself.

The same email said Foster included the material "for the sole purpose of harassing Defendants' client, Sony." According to the sworn account, Sony had asked for the meeting.

Every sworn statement about Sony so far comes from Foster's side, and Sony has not said a word in court. ADOTAT has asked both Sony and WPP to respond.

The exhibits also show how fast WPP changed course.

Foster filed his amended complaint, Sony material included, on Thursday, August 13. At 11:53 a.m. the next day, WPP's counsel emailed the court: "After reviewing Plaintiff's eleventh hour Amended Complaint and accompanying exhibits," WPP would withdraw its pending motion to dismiss and propose a briefing schedule. The email raises no objection on grounds of confidentiality, privilege or Sony. Two minutes later, Justice Borrok marked the motion withdrawn.

On Monday at 2:00 p.m., WPP sent the demand letter. It gave Foster until 9:00 a.m. the next morning to withdraw the complaint, name his source and return company property.

At 3:25 p.m., Brewer IV replied: "We will provide a response to your letter tomorrow."

On Tuesday at 5:02 p.m., WPP wrote to the court: "After more than 24 hours, Plaintiff has not provided a substantive response." The email does not mention the reply 85 minutes after the letter promising one that day. Foster's five-page response arrived that evening.

WPP has a grievance of its own here, and it is a fair one. In an August 13 email, its counsel complained that Foster filed the amendment "hardly two business days" before a long-scheduled argument on WPP's motion to dismiss, and called it a "lack of professional courtesy." Brewer also missed WPP's 9 a.m. deadline. But what reached the judge was WPP's summary of the exchange, not the timestamps.

Sony is not WPP's only secrecy fight. The company also says Foster's text messages with Nicola McCormick, WPP's general counsel, are privileged and never should have been filed.

Foster's brief says WPP has been quoting those same communications for months. WPP's first motion to dismiss called them "the Complaint's sole allegation that could possibly constitute 'whistleblower' activity." And according to the brief, WPP's September 2 motion to dismiss the amended complaint quotes paragraphs 91 through 98 at length, without redaction. That motion came after WPP asked for sanctions over those same paragraphs.

In his own affirmation, Foster says he asked McCormick to keep his concerns "strictly, strictly between us" because he "feared retaliation," not because he thought he was seeking legal advice. "I did not treat them as confidential legal communications belonging to WPP," he wrote.

WPP has put commercially sensitive material on the public docket itself. In January, it publicly filed Foster's full December 2024 report to Lesser. According to Foster's brief, that report says GroupM books "nearly $1bn of global net sales in non-product related income (rebates, services and purchase risk trading inventory)." WPP has never moved to seal it.

Here is the limit of what the new filings prove. Condon and Zhang work for the law firm suing WPP. Neither affirmation names the Sony representative who filled out the form, or says who from Sony attended the May 19 meeting.

WPP will draw a distinction, and it is a fair one: Sony not asking for confidentiality is not the same as Sony authorizing its findings to appear in a public lawsuit against its own agency. Only Sony can settle that.

Sony has not appeared in the case, moved to intervene or taken any public position. Foster's brief makes the point directly: "Sony is a nonparty that has not appeared, moved to intervene, or expressed any view." WPP's motions speak for Sony's interests without any filing from Sony.

Foster, in his own sworn statement, says the Sony review confirms what he told WPP's leadership for years. "The conduct described in the Sony materials confirms the behavior I reported," he wrote. "Sony's independent review draws the same conclusion and corroborates the reports I made."

"Mr. Foster named names and provided specific, detailed reports of undisclosed profiteering by Defendants in the form of rebates," William A. Brewer III, Foster's lead counsel, told ADOTAT. "Mr. Foster stands behind the allegations made in his Amended Complaint" and "remains confident that he will prevail."

WPP's motions for sanctions, disqualification and sealing are pending before Justice Borrok, as is its motion to dismiss.

This story is based on filings made September 9 in Foster v. WPP plc et al., Supreme Court of the State of New York, Commercial Division, Index No. 659721/2025. It draws on the sworn affirmations of Ryan Condon, Xinni Zhang, Eric Gregory and Richard Foster, the email exhibits attached to Gregory's affirmation, the March 2026 confidentiality stipulation and Foster's memorandum opposing sanctions. ADOTAT has not seen WPP's sanctions motion or its unredacted filings, and quotes from them come from Foster's papers or prior press reports. The affirmations are sworn statements by Foster's side and have not been tested in court. Foster's counsel's communications office alerted ADOTAT to the filings. ADOTAT asked Sony Group Corporation and WPP for comment and will update this story with any response. ADOTAT has no financial relationship with any party to the case.