Grant Thornton Advisors has announced it has signed a definitive agreement to acquire the financial, insurance, and advisory services firm CBIZ for $5 billion.

The deal, which is the largest of its kind since the merger between Price Waterhouse and Coopers & Lybrand to create PwC, will see Grant Thornton become the fifth-largest provider of professional, tax, and advisory services in the US.

Once complete, the new combined firm will cover more than 20 countries and territories, operate a workforce of more than 34,500 professionals, and generate almost $7.5 billion in revenue.

Under the terms of the deal, Grant Thornton Advisors will provide CBIZ shareholders with $55 cash per share and spin out CBIZ’s Benefits and Insurance Services segment into a standalone entity. The new entity, as well as the wider deal, is backed by incremental equity from the investment firm New Mountain Capital.

Jim Peko, chief executive of Grant Thornton Advisors LLC and leader of the Grant Thornton Advisors multinational platform, said: “By combining our multinational platform with CBIZ's strong market presence, we're broadening our ability to support businesses through every stage of growth, from early development to global scale.

“Together, we'll bring the quality, scope and capabilities clients need to navigate an increasingly complex and rapidly evolving business environment.”

In recent years, several major acquisitions and mergers in US accounting have concentrated the middle market and put firms in more direct competition with the Big Four professional services firms: Deloitte, EY, KPMG, and PwC.

In 2024, CBIZ acquired the New York-based accounting firm Marcum for $2.3 billion and in 2025, the UK’s Baker Tilly and US professional services firm Moss Adams combined for $7 billion.

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