Aon completed its acquisition of USI Insurance Services for approximately $17 billion, marking the largest insurance brokerage transaction of 2025 and the third-largest in sector history. The deal hands Aon 175 additional offices across North America and positions the combined entity as the second-largest insurance broker globally behind Marsh McLennan, with $24 billion in estimated combined revenue.
USI operates primarily in middle-market commercial insurance and employee benefits, segments where Aon has historically concentrated on Fortune 500 accounts and complex risk placements. The acquisition adds 8,500 USI employees to Aon's 50,000-person workforce and delivers immediate scale in regional distribution channels that institutional clients increasingly demand for multi-location exposures. Aon paid roughly 11x USI's estimated $1.5 billion EBITDA, a modest premium to recent brokerage multiples but justified by USI's 18% organic growth rate over the prior three years.
The timing reflects structural shifts in both reinsurance capacity and enterprise risk appetite. Global reinsurance rates rose 22% in the January 2025 renewal season following three consecutive years of catastrophic losses exceeding $100 billion annually. Corporations responding to tighter capacity are consolidating broker relationships to maximize treaty leverage, rewarding scale platforms that can deliver both placement certainty and claims advocacy. Aon's expanded middle-market footprint allows it to cross-sell specialty lines and captive structuring services that smaller brokers cannot support, embedding the platform deeper into client risk finance architecture.
Private equity's appetite for brokerage platforms also drove the valuation. TPG and Kohlberg Kravis Roberts held a combined 68% stake in USI, acquired across multiple transactions since 2019. Their exit at 11x EBITDA validates the thesis that recurring commission revenue tied to hardening premium rates offers inflation-protected cash flows superior to direct insurance carrier exposure. Aon financed the transaction with $9 billion in new debt and $8 billion in equity, maintaining its leverage ratio below 3.0x and preserving financial flexibility for additional tuck-in acquisitions.
Allocators should monitor Aon's integration execution over the next 18 months, particularly its ability to retain USI's producer talent amid competing offers from Marsh and Arthur J. Gallagher. Producer defections typically occur within the first 12 months post-close when earnout terms crystallize and non-compete provisions expire. The combined platform faces regulatory review in North America, though antitrust risk appears minimal given limited geographic overlap and the fragmented nature of middle-market distribution. Watch for Aon's Q2 2025 earnings call in late July for initial cross-sell metrics and organic growth guidance.
The transaction removes $1.5 billion in annual EBITDA from the private market and returns it to public hands, reversing a decade-long trend of private equity roll-ups in specialty insurance distribution.