Aon Buys USI Insurance for $17 Billion as Verisk Pegs Annual Catastrophe Losses at $171 Billion

Aon is buying USI Insurance Services from KKR and other shareholders in a deal worth $17 billion, the companies announced Monday, August 31. It's the latest sign that the insurance brokerage business is consolidating fast, right as a separate industry report from Verisk says insurers face record-high catastrophe exposure.

The Aon-USI Deal

USI is the 10th-largest insurance broker in the United States, according to the deal announcement, with about $3 billion in annual revenue, more than 10,500 employees, and nearly 200 offices nationwide. The company sells property and casualty insurance, employee benefits, personal risk products, and retirement services.

Aon says the acquisition pushes it deeper into the U.S. middle-market segment, a business worth more than $40 billion that accounts for over one-third of all U.S. commercial property and casualty premiums. It also gives Aon more reach into the excess and surplus insurance market, which covers risks traditional insurers won't touch and represents about 26% of U.S. commercial P&C premiums, according to Aon's own figures.

"Combining with USI will establish the premier U.S. middle-market platform, deepen our context advantage and position Aon to accelerate organic growth," said Greg Case, Aon's president and CEO, in a statement.

Aon expects the combined middle-market business to generate roughly $395 million a year in extra earnings from cost cuts and revenue growth, though the deal won't start boosting adjusted earnings per share until 2028. The company plans to pay for the acquisition with new debt and says it will prioritize paying that debt down over buying back shares once the deal closes, expected in the fourth quarter of 2026 pending regulatory approval.

Once it closes, USI chairman and CEO Mike Sicard becomes Aon's president and global CEO of middle market. "Joining Aon represents a truly energizing next chapter for our firm and an opportunity to accelerate our momentum as part of the Aon United platform," Sicard said.

This isn't Aon's first big swing at the middle market. The company bought NFP for $13 billion in April 2024, then later sold most of NFP's wealth-management arm back to private-equity firm Madison Dearborn Partners for about $2.7 billion to keep NFP focused on risk, insurance, and benefits.

For KKR, this is a major exit. The private-equity giant bought USI alongside Canadian pension fund CDPQ for about $4.3 billion back in 2017, then poured in more than $1 billion in additional investment since. Nine years later, that bet is cashing out at nearly four times the original purchase price.

Catastrophe Losses Hit a Record Benchmark

Separately, Verisk (Nasdaq: VRSK), the data analytics firm that builds catastrophe models used across the insurance industry, released its 2026 Global Modelled Catastrophe Losses Report on September 1. The headline number: insurers worldwide should be prepared to withstand $171 billion in insured catastrophe losses in an average year, up $19 billion from last year's estimate and the highest figure Verisk has ever published.

That number went up even though 2025 was the first year in a decade with zero U.S. hurricane landfalls, according to Verisk. "A quiet hurricane season can lead markets to respond as if risk has eased: rates soften, insurers keep more risk on their own books, and more capital competes to write new business," said Rob Newbold, president of Verisk Catastrophe and Risk Solutions. "But 2025 reminds us that the underlying risk landscape has changed and years without significant losses from U.S. hurricane activity no longer signal a quieter catastrophe environment."

For the sixth straight year, global insured catastrophe losses topped $100 billion, driven less by hurricanes and earthquakes and more by record-setting wildfires and widespread severe thunderstorm activity, including hail, wind, and tornado damage spread across many communities rather than one big event, per Verisk.

The $171 billion figure is a modeled, long-term average annual loss estimate, not a prediction for 2026 or any single year. It's a benchmark for insurers to plan around.

Since Verisk started publishing this report in 2012, that estimate has nearly tripled, from $59 billion to $171 billion. Some of that jump is genuine risk growth. But Verisk's own report notes the increase also reflects the company expanding its models to cover more than 20 additional countries, methodology upgrades, and, most significantly, growth in the total value of insured property worldwide. More buildings, more expensive buildings, more stuff to insure, means bigger dollar losses even if storm frequency stayed flat.

These two developments are separate and unrelated, but they paint a consistent picture: insurance brokerage is consolidating into fewer, bigger players, while the underlying cost of the risk those brokers are pricing keeps climbing.

The open question is what happens to premiums for the small and midsize businesses Aon says it's targeting. Aon says combining with USI will drive down costs through scale. Whether that translates into lower prices for the plumbing companies and regional manufacturers who actually buy these policies, or just fatter margins for Aon, will show up in renewal notices well after the deal closes in the fourth quarter of 2026 and regulators sign off.