IPG’s Top Media Exec Is Out as Omnicom Merger Shakes Up Leadership Ranks—Read the Internal Memo Here

The merger between major holding companies Omnicom Group and Interpublic Group (IPG) continues to shake up leadership ranks. Eileen Kiernan, the chief executive of IPG’s media division, IPG Mediabrands, will step down from her role as the firm is absorbed into the new company, according to an internal memo reviewed by ADWEEK.

Kiernan’s announcement is part of the ongoing ripple effects from Omnicom’s $13 billion acquisition of IPG, finalized last week, which has already seen thousands of jobs axed, the shuttering of three historic ad agencies, and a major executive reshuffling. As part of the merger, IPG Mediabrands will be folded into the combined company’s new media division, Omnicom Media.

“As IPG Mediabrands evolves into the next chapter of Omnicom Media, regrettably we will be saying goodbye to a number of our people, including some of our global leaders,” Kiernan wrote in the memo, which was sent to staff on Monday. “I want to thank all for your dedicated service, unwavering commitment, partnership, and friendship, particularly over these past three years. We’ve been fortunate to have had this time together, and we wish you all good things in the chapter ahead.”

She continued: “As for me, after an incredible 14 years with IPG, I too will be moving on to embrace my next adventure—full of family and friends. My departure won’t be immediate, however. I’ll be staying on through the first few months of 2026, helping Flo [Omnicom Media CEO Florian Adamski] with the transition to ensure a smooth landing for you and our clients into the new Omnicom.”

Kiernan took the top post at IPG Mediabrands in 2023 after a nearly five-year stint as global president for the agency network’s Johnson & Johnson account.

In her email Monday, she added that “[m]ore changes will be announced in the coming days,” but underscored the company’s ongoing “commitment to excellence in client partnership, our continued investment in an unparalleled suite of connected capabilities, and our commitment to a powerful, unifying operating model.”

Kiernan did not respond to a request for comment. Representatives for the combined holding company, Omnicom, declined to comment.

Florian Adamski, who became CEO of Omnicom Media Group in 2021, will helm the newly consolidated media operations, which is now being referred to as Omnicom Media (sans “Group”).

The division will house six media agencies, according to a LinkedIn post from Adamski: OMD, Hearts & Science, and PHD from the Omnicom side, as well as UM, Initiative, and Mediahub from the IPG side. Commercial delivery will be managed through three organizations: Omnicom Media Investment and Outdoor Media Group from the Omnicom side, and Kinesso from the IPG side. Acxiom, the data powerhouse acquired by IPG in 2018, will also slot under the Omnicom Media umbrella, as will Annalect, an Omnicom data firm.

Omnicom Media will also oversee a handful of specialized service organizations including Omnicom Media Health, financial services organization Ptarmigan, cloud consulting group TRKKN, Optimum Sports, entertainment and sports firm Fuse, and influencer shop Creo.

Leadership of Omnicom Media will primarily be made up of executives from the former Omnicom Media Group. Exceptions include Justin Wroe, who will be chief commercial officer and was previously the U.S. CEO of IPG Mediabrands. Daniel Fox, IPG Mediabrands’ chief investment officer, and Jonathan Rigby, its chief strategy officer, will take on the same titles under the new Omnicom Media banner. 

Read Kiernan’s full email to staff below:

Hello everyone,

I have been giving this moment a lot of thought now that we are at the starting line of our next chapter. In an industry built on incredible talent and powerful capabilities that drive growth for clients, we will be a powerhouse! And as excited as I am for what’s ahead, I am also filled with gratitude and pride as I reflect on how we’ve grown together as a team and how far we’ve come.

As you will have seen from recent updates, our coming together as Omnicom Media brings change, including new leadership in Florian Adamski. I’ve spent considerable time with Flo over the last few months and have seen firsthand how he’s embracing this opportunity with care and dedication. He is intensely client-focused, understands how critical our teams are to success, and has a thoughtful and strategic approach. We will be in good hands.

As IPG Mediabrands evolves into the next chapter of Omnicom Media, regrettably we will be saying goodbye to a number of our people, including some of our global leaders. I want to thank all for your dedicated service, unwavering commitment, partnership, and friendship, particularly over these past three years. We’ve been fortunate to have had this time together, and we wish you all good things in the chapter ahead.

As for me, after an incredible 14 years with IPG, I too will be moving on to embrace my next adventure—full of family and friends. My departure won’t be immediate, however. I’ll be staying on through the first few months of 2026, helping Flo with the transition to ensure a smooth landing for you and our clients into the new Omnicom.

More changes will be announced in the coming days, and I know some may create uncertainty in the short term. But here’s what won’t change: our shared commitment to excellence in client partnership, our continued investment in an unparalleled suite of connected capabilities, and our commitment to a powerful, unifying operating model. In fact, the transformational work done across crafts will not be discarded—instead it will be evolved and strengthened as a key part of how Omnicom Media will organize and operate going forward.

It has been the honor of my lifetime to travel alongside you these past three+ years. I can’t wait to celebrate the new heights you’ll undoubtedly achieve.

Stay focused, keep shining—I’ll be cheering you on, loudly and proudly.

Thank you,

Eileen Kiernan
Global CEO, IPG Mediabrands