The news: 2025 revealed both the strengths and vulnerabilities of the traditional agency model. Mergers, mass restructuring, and rapid AI adoption caused the industry’s long-established hierarchy to realign.

Here are three of the ad groups whose highs and lows EMARKETER covered in 2025—and what these findings mean for advertisers in 2026.

Omnicom closed its mega-merger: Omnicom became the largest advertising holding company globally by revenues after completing its merger with IPG. The company made a wave of massive changes immediately following the deal that are setting the standard for the new era of advertising:

• Omnicom retired legacy ad agency networks including DDB, FCB, and MullenLowe as part of the merger, while shedding about 4,000 jobs as a consequence of consolidation.
• Along with the merger came a vast expansion of Omnicom’s AI capabilities. The company announced its decision to expand enterprise genAI capabilities across all teams and integrate its genAI technology across its agencies to deliver personalized content at scale.
• As a result, advertisers were left preparing for an agency landscape with fewer partners, where AI-driven capabilities have become standard and consolidated services serve as key competitive differentiators.

Publicis stayed strong: Publicis led the pack in 2025. The holdco posted strong revenue gains between Q1 and Q3, with wins largely driven by successful AI investment, data-driven strategy, and major account wins.

• Publicis’ heavy AI investment proved promising. The company reinforced its CoreAI platform while integrating AI into media planning, targeting, and execution. Seventy-three percent of its operations and 80% of its media revenues are now AI-powered, giving Publicis a significant edge in performance.
• The holdco strengthened its data capabilities through key acquisitions including data-management company Lotame, allowing Publicis to enhance its first-party targeting system and audience graph.
• 2025 was marked by major account wins for Publicis, including Coca-Cola’s North American media business, Mars’ global media account, PayPal’s global media business, and Paramount’s global media account.

WPP fell behind: 2025 was also a year where the traditional agency model showed cracks, exemplified by WPP’s notable decline.

• Once the largest global advertising group, WPP took major hits to its earnings in 2025. WPP saw profits drop 71% pre-tax in the first half of the financial year, citing tariff policies and cuts in client spending.
• WPP’s shrinking market capitalization—decreasing from around £24 billion ($22.2 billion) in 2017 to £3.1 billion ($2.9 billion) in 2025—led to its removal from the FTSE 100 in December.
• Publicis’ account wins came at the expense of WPP, which lost business from Coca-Cola, PayPal, and Mars.
• WPP failed to match its competitors’ strength in AI and data and was slow to prove the effectiveness of its AI initiatives. Combined with heightened pressure from tech platforms offering self-service ad tools, WPP struggled to prove its value in an increasingly crowded digital ad ecosystem.
• The Times reported in November that WPP could acquire Havas in an effort to compete with the newly merged Omnicom-IPG.

What advertisers can anticipate in 2026: The ad agency landscape is moving toward AI automation and consolidation. Advertisers can anticipate an agency ecosystem where AI capabilities become fully embedded in planning and execution, fewer and more advanced partners dominate, and competition hinges on data-rich, tech-enabled solutions.

As a result, brands must now evaluate whether their partners can go beyond delivering on creative capabilities to prove their strength in the ability to integrate AI and adapt to shifting market dynamics.