NEW YORK—Omnicom has acquired the Interpublic Group in a deal that most observers believe will create the world’s largest marketing services group with combined 2023 revenue of $25.6 billion. The merged entity will be parent to four of the world’s top 20 public relations agency brands.

The two holding companies announced today that their boards of directors have unanimously approved a definitive agreement. Omnicom will acquire Interpublic in a stock-for-stock transaction.

“The combined company will bring together the industry’s deepest bench of marketing talent, and the broadest and most innovative services and products, driven by the most advanced sales and marketing platform,” the two organizations said in a press release.

Based on 2023 revenues and numbers reported so far this year, it is likely that the merger will take the two agencies past Publicis Groupe and WPP to become the world's largest marketing services group.

In terms of public relations, Omnicom owns top 20 firms FleishmanHillard and Ketchum, as well as smaller operations such as Porter Novelli and MMC, as well as several public affairs brands. Interpublic is parent to The Weber Shandwick Collective (which includes Current Global) and Golin.

It is unclear how the merger will impact these public relations brands, although it appears there are no immediate plans for restructuring. The press releases says that transaction is expected to generate annual cost synergies of $750 million but it is unclear where those savings will come from.

Under the terms of the agreement, Interpublic shareholders will receive 0.344 Omnicom shares for each share of Interpublic common stock they own. Following the close of the transaction, Omnicom shareholders will own 60.6% of the combined company and Interpublic shareholders will own 39.4.

The new Omnicom will have more than 100,000 employees and operations spanning media, precision marketing, CRM, data, digital commerce, advertising, healthcare, public relations and branding.

“This strategic acquisition creates significant value for both sets of shareholders by combining world-class, highly complementary data and technology platforms enabling new offerings to better serve our clients and drive growth,” said John Wren, chairman & CEO of Omnicom. “Through this combination, we are poised to accelerate innovation and harness the significant opportunities created by new technologies in this era of exponential change.

Wren will remain chairman and CEO of Omnicom. Phil Angelastro will remain EVP & CFO  and current Interpublic CEO Philippe Krakowsky and Omnicom COO Daryl Simm will serve as co-presidents and COOs. krakowsky will also be co-chair of the integration committee post-merger.