Arthur Sadoun responded to the proposed mega-deal in a video to staff, a week after Snoop Dogg declared Publicis the world’s largest holding company.

The $13.25 billion acquisition by the ad holding company Omnicom of Interpublic Group has industry insiders speculating about more M&A to come.

A deal of this magnitude will have implications far beyond Omnicom and IPG. Agency heads tell us what they think of the motives – and what it means for them.

In reality, while this merger shakes up the commercial world, its impact on the public sector feels overstated. The government contracting market is robust, decentralized, and competitive by design. Omnicom’s acquisition of IPG might grab headlines, but on the ground, the dynamics of agency-level competition will likely remain unchanged.

The deal to create the world's biggest ad-agency company reflects a challenged sector and the importance of scale, data, and AI to remain competitive.

Omnicom Health Group (OHG) CEO Matt McNally has spent his entire career in the medical marketing industry and helmed numerous marquee agencies. He has been with OHG since 2022, joining the agency after just over a year as global president of Dentsu Health. Prior to that, he served as CEO of Outcome Health for nearly three years.

Omnicom and IPG expect to make $750m (£587m) in “annual cost synergies”, and there was no immediate word on where the cuts may fall. The combined company is expected to have a stock market capitalisation of more than $30bn (£23bn).The deal is expected to close in the second half of 2025, the companies said.