Aon has struck a $US17 billion ($23.7 billion) deal to acquire brokerage and consulting group USI Insurance Services as part of a targeted US expansion.

USI, based in Valhalla, New York, has nearly 200 offices and provides property and casualty, employee benefits, personal risk and retirement solutions to large clients, middle market companies, smaller businesses and individuals.

The business will be purchased from Kohlberg Kravis Roberts, which has owned USI since 2017 with other investors as part of its Strategic Holdings portfolio.

“When we acquired USI, we saw a fantastic company that was uniquely positioned to help address the risk management, insurance and employee benefits-related needs of businesses across America,” KKR partner Chris Harrington said.

“USI has continued to innovate and extend its leadership position, and we believe Aon is the ideal long-term partner to support the next chapter of its growth.”

Aon says the transaction establishes a premier platform in the large and growing US middle market, building on its 2024 NFP acquisition.

“In a time of rising complexity and volatility, creating better outcomes for clients across their risk and people challenges requires a combination of capabilities and expertise supported by proprietary data, analytics and technology,” president and CEO Greg Case said.

The all-cash deal is expected to close in the fourth quarter, subject to usual conditions and regulatory approvals.