Published: September 3, 2026 | Category: Deals & M&A

The broker turns to fresh debt for its largest deal since NFP, handing KKR the exit on a hold it began in 2017 and accelerating the roll-up of America’s mid-sized insurance advisers.

Aon has agreed to buy USI Insurance Services from KKR for $17bn, its largest acquisition since the $13bn purchase of NFP in 2024 and a further bet on advising mid-sized US companies on their risk. The deal, confirmed by Aon on Monday, values USI at about $16.7bn net of roughly $278mn in tax attributes, or about 14.5 times the broker’s synergised trailing-twelve-month adjusted earnings before interest, taxes, depreciation and amortisation.

Aon said it would fund the purchase and related costs with new debt. The transaction is expected to close in the fourth quarter of 2026, subject to regulatory approval, with the two brokers operating separately until then.

USI, based in Valhalla, New York, is the tenth-largest insurance broker in the US, with about $3bn in annual revenue, roughly 10,500 employees and close to 200 offices. It sells commercial insurance, employee benefits and retirement services to mid-market companies, the segment between small local agencies and the multinational accounts that dominate Aon’s traditional book.

“Combining with USI will establish the premier US middle-market platform, deepen our context advantage and position Aon to accelerate organic growth,” Greg Case, Aon’s president and chief executive, said in a statement. Mike Sicard, USI’s chairman and chief executive, will become president of Aon and global chief executive of its middle-market business once the deal closes.

The purchase extends a strategy Aon set in motion with NFP, whose middle-market and wealth advisers it bought two years ago. USI adds wholesale distribution and direct access to the excess and surplus market through managing general agents and underwriters, along with the USI One analytics platform that Case singled out as a draw. Aon expects the deal to generate about $395mn in annual run-rate net adjusted EBITDA from revenue and cost synergies, and to lift adjusted earnings per share from 2028.

The acquisition tightens an already concentrated industry. Aon ranks third among US brokers by revenue, at about $8.15bn, behind Marsh & McLennan and Arthur J Gallagher, and the middle market has become the main battleground as the largest advisers chase organic growth beyond their blue-chip accounts. Gallagher and Marsh have spent years acquiring regional agencies to reach the same clients.

For KKR, the sale caps a multi-year hold. The private equity firm and Canadian pension fund Caisse de dépôt et placement du Québec bought USI from Onex in 2017 for $4.3bn, and KKR invested a further $1bn in 2023 to become the largest shareholder. The exit lands amid a run of large KKR disposals in 2026: Apollo agreed last month to buy a co-controlling stake in Atlantic Aviation at a valuation of nearly $10bn, with KKR retaining a holding, and KKR sold the data-centre cooling company CoolIT Systems to Ecolab for $4.75bn earlier in the year.

The timing reflects a wider thaw in dealmaking after two slow years, as sponsors seek to return cash to investors and strategic buyers with strong balance sheets pursue scale. Whether Aon can absorb a second large brokerage while carrying the added debt, without disrupting USI’s producers, will determine how much of the promised $395mn in synergies actually reaches the bottom line.

Sources