Grant Thornton Advisors has agreed to acquire professional services firm CBIZ in a $5 billion all-cash transaction, marking one of the largest mergers in the U.S. accounting and consulting industry in decades. The acquisition will significantly expand Grant Thornton’s scale and position the combined company as the fifth-largest provider of accounting, tax and advisory services in the United States, behind only the industry’s dominant Big Four firms—Deloitte, PwC, EY and KPMG.
Under the agreement, CBIZ shareholders will receive $55 per share in cash, representing a 17.8% premium over the company’s previous closing stock price. Investors reacted positively to the announcement, sending CBIZ shares sharply higher in premarket trading as markets recognized both the premium offered to shareholders and the strategic significance of the merger. The transaction also includes a “go-shop” provision that allows CBIZ to seek competing offers until August 27, ensuring the company fulfills its fiduciary duty to maximize shareholder value before the acquisition becomes final.
The merger reflects a broader wave of consolidation across the accounting and professional services industry. Mid-sized firms have increasingly pursued mergers and acquisitions to compete more effectively with the Big Four, whose global networks dominate the market for large corporate clients. Recent transactions—including CBIZ’s acquisition of Marcum and the merger between Baker Tilly and Moss Adams—have demonstrated how firms are seeking greater scale, broader service offerings and stronger international capabilities.
Once completed, the combined organization is expected to generate nearly $7.5 billion in annual revenue, employ approximately 34,500 professionals, and operate in more than 20 countries and territories. Grant Thornton executives said the transaction will allow the firm to provide a broader range of tax, audit, consulting and advisory services while supporting businesses at every stage of growth, from privately held companies to multinational corporations.
A key financial partner behind the deal is New Mountain Capital, the private investment firm that became a strategic investor in Grant Thornton in 2024. New Mountain will provide additional equity financing to support the acquisition. After the transaction closes, CBIZ’s benefits and insurance services division will be separated into an independent company backed by New Mountain, allowing Grant Thornton to concentrate on its core accounting, tax and advisory businesses while preserving value in CBIZ’s insurance operations.
Grant Thornton Chief Executive Jim Peko described the acquisition as an opportunity to strengthen the firm’s multinational platform while expanding its ability to serve middle-market businesses. CBIZ CEO Jerry Grisko said the combination brings together organizations with complementary cultures and service offerings, creating new opportunities for employees and enhanced capabilities for clients. Both companies emphasized that the merger is designed to accelerate growth rather than fundamentally change their focus on serving mid-sized businesses and privately held companies.
The agreement remains subject to shareholder approval and customary regulatory reviews, with the companies expecting to complete the transaction during the fourth quarter of 2026. Industry analysts believe the merger will intensify competition among firms outside the Big Four by creating a larger organization capable of pursuing more complex clients and broader international engagements.
The acquisition represents a milestone in the evolution of the accounting industry. By combining their resources, Grant Thornton and CBIZ aim to create a stronger national and international platform capable of competing more effectively in an increasingly consolidated market. While the Big Four are expected to remain dominant, the deal signals that large mid-market firms are investing aggressively to narrow the gap through scale, technology and expanded advisory capabilities.
