How Adland's Power Brokers Are Reshaping Agency Models

For the first time, the Australian heads of all five major global advertising holding companies will share a single stage at Mumbrella360 on May 28, 2026, in Sydney.

The session, titled "Disrupt, Consolidate, Accelerate: Who Wins Adland's Big Reset?", will feature Michael Rebelo (Publicis), Nick Garrett (Omnicom), Rose Herceg (WPP), James Wright (Havas), and Rob Harvey (Dentsu). It is scheduled as the closing panel of the three-day summit at Carriageworks, Sydney, running May 26 to 28.

Five CEOs, One Stage, One Pointed Question

The panel will be moderated by Rowena Millward of MacMorgan. Discussion topics are expected to cover AI's growing role in advertising, shifting client expectations, and changing operating models across the industry.

The gathering is rare. Having all five holding company chiefs address the same questions, at the same time, in the same room reflects how broadly the industry now recognizes that its structural pressures require collective, not separate, conversations.

For marketing executives across Asia tracking where global agency power is shifting, the session offers a direct window into how the world's largest advertising groups are responding to disruption simultaneously.

A Market in Active Reshuffling

The Australian advertising market provides sharp context for the panel's themes. Publicis Groupe ANZ led Australia's net new media business rankings in 2025, with the group posting 5.9% organic growth globally. CEO Michael Rebelo attributed the performance to "relentless focus on clients, capability enhancement, talent magnetism and innovation in data and technology."

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Mission MediaMission Media

WPP secured the single largest media account win in Australia that year, taking the A$140 million consolidated Suncorp account directly from Omnicom's OMD. Despite that win, WPP globally experienced a revenue decline of 5.5% to 6% in Q2 2025, forcing a revision to its full-year outlook.

The gap between Publicis and WPP in Australia's net new billings rankings was approximately A$50 million, illustrating how tightly contested market leadership remains.

The Omnicom-IPG Merger Adds Weight to the Room

Omnicom's Australian CEO Nick Garrett will appear on the panel while his company's US$13 billion acquisition of Interpublic Group (IPG) moves toward a 2026 close. If completed, the combined entity would become the world's largest advertising holding company by scale, fundamentally altering the competitive landscape that all five panelists currently operate within.

Omnicom has also spent six years building its digital consulting arm, Credera, to 4,000 employees globally. That investment positions Omnicom as a managed services provider alongside its traditional agency business, a distinction that speaks directly to the panel's "Accelerate" theme.

Independent Agencies Enter the Conversation

One dimension the panel's framing does not fully capture: independent media agencies in Australia won A$139 million in new business in 2025. More than A$75 million of that came directly from holding companies. Nunn Media ranked as the third most-prolific new business winner among all Australian media agencies that year.

No independent agency CEO will share the Mumbrella360 stage. That absence is itself a data point for CMOs attending the session.

Different Technology Bets, Same Stage

Each of the five holding companies is pursuing a distinct technology strategy. Publicis acquired Australian retail media platform Citrus Ad for over A$200 million in 2021, giving it an early structural advantage in one of digital advertising's fastest-growing channels. WPP has centralized its data and cloud capabilities through its WPP Open platform. Omnicom's Credera build-out moves it toward technology consulting territory previously occupied by firms like Accenture.

These are not variations on the same model. They are different bets on what an advertising holding company should be in 2026 and beyond.

Mumbrella360 2026 runs May 26 to 28 at Carriageworks, Sydney, under the theme "Catalyst."