Aon writes a US$17bn cheque for USI and moves into the American middle market
The largest disclosed transaction in our Q3 sample, and the second time in three years Aon has paid more than US$10bn for a US broker.

Aon disclosed a US$17.0bn cash payment for USI Insurance Services in an 8-K exhibit filed on 11 September. The figure includes repayment of USI’s debt, so it is closer to an enterprise value than an equity cheque. That matters when you compare it with the other deals in this report. It is not an overpayment on the equity.
USI serves commercial property and casualty, employee benefits and personal-risk clients across the United States. For Aon, whose core has long been large corporate and specialty risk, that is a distribution footprint it could not build organically at any reasonable speed. The deal follows Aon’s US$13.4bn purchase of NFP in 2024, which pointed the same way.
All-cash consideration at this size says two things. Aon is comfortable taking on leverage against broking cash flows. And the seller wanted certainty over a share-based structure. Both fit a market where broking assets have traded as quasi-infrastructure: recurring commission income, low capital intensity and pricing power that follows premium rates.
Acquiry’s read
This is a distribution deal wearing a broking badge. Aon is buying tens of thousands of mid-sized client relationships it can sell analytics, reinsurance and benefits consulting into.
What to watch
- Antitrust review in US regional markets where both firms place commercial lines.
- Aon’s leverage guidance and whether it pauses buybacks to fund the payment.
- Producer retention. Mid-market broking value leaves the building with the people.














