Aon to Buy USI in $17.0 Billion Deal
The global risk adviser said the combination will establish the premier U.S. middle-market platform after its 2024 NFP acquisition.
Aon plc (AON) agreed to acquire USI for $17.0 billion, a move the company said will create the leading platform in the large and growing U.S. middle-market insurance segment.
The transaction is expected to close in the fourth quarter of 2026.
President and Chief Executive Officer Greg Case said the deal builds on Aon’s 2024 acquisition of NFP. “Combining with USI will establish the premier U.S. middle-market platform, deepen our context advantage and position Aon to accelerate organic growth,” Case said.
Aon, which serves clients in more than 120 countries, framed the purchase as the next step in a middle-market strategy that began with NFP. The company said the USI combination will extend that platform and deepen its “context advantage” in the segment.
The $17.0 billion price tag is the largest disclosed figure in the announcement. The release did not specify whether the consideration is cash, stock, or a mix, and it did not state an exchange ratio or a premium.
U.S. middle-market broking has drawn sizable deals from other advisers in recent months. WTW agreed in December 2025 to buy Newfront for an upfront $1.05 billion plus up to $250 million of contingent consideration, strengthening its presence in the U.S. middle market and high-growth specialties. Brown & Brown agreed in June 2025 to acquire Accession Risk Management Group for gross consideration of $9.825 billion. Gallagher closed its purchase of AssuredPartners in August 2025, further expanding its retail middle-market property/casualty and employee-benefits focus.
Aon’s own 2025 NFP-related activity included a sale of certain middle-market-focused businesses to Madison Dearborn Partners for an estimated $2.7 billion at close, with those businesses to operate under a unified brand after the transaction.
The company said the USI deal is expected to close in the fourth quarter of 2026, subject to customary conditions.