Aon has agreed to buy USI Insurance Services from KKR and other shareholders in a deal worth $17 billion, a transaction that would push the broking and consulting giant deeper into the middle-market territory it first staked out with its purchase of NFP two years ago.
The two firms confirmed the agreement on Monday, ending days of speculation after the Wall Street Journal reported over the weekend that a deal was close. On a net basis, after accounting for roughly $278 million in tax attributes, the price works out to $16.7 billion – or about 14.5 times USI's synergized trailing-twelve-month adjusted EBITDA.
Valhalla, New York-based USI is the tenth-largest insurance broker in the country, generating around $3 billion in annual revenue through more than 10,500 employees spread across nearly 200 US offices. It sells property and casualty coverage, employee benefits, personal risk products and retirement plan advice, largely to businesses too small for the largest brokers but too complex for a local agency.
Under the deal, USI chairman and chief executive Mike Sicard will become president of Aon plc and global CEO of its middle-market business, reporting directly to Aon chief executive Greg Case and taking a seat on the firm's executive committee.
Case said the deal would make Aon "the premier US middle-market platform," deepening what he calls the firm's data and analytics edge over rivals and positioning it to grow faster without relying on price increases. In an interview with the Wall Street Journal, he put the rationale more plainly: "We see this having a financial impact almost immediately." The company, he added, is essentially exporting capabilities it already has into a market it hasn't fully tapped.
Aon puts the US middle market at more than $40 billion in size, accounting for over a third of the country's commercial P&C premium. The firm also expects the deal to widen its foothold in excess and surplus lines – a segment distributed through wholesalers and managing general agents that now makes up roughly a quarter of US commercial P&C premium and remains one of the fastest-growing corners of the industry.
Aon says the combination should generate about $395 million a year in run-rate synergies once fully integrated, and it expects the deal to add to adjusted earnings per share starting in 2028. The company plans to fund the purchase entirely with new debt, and says it intends to keep its current credit ratings (Baa2 at Moody's, A- at S&P) by holding off on share buybacks while it pays that debt down. BofA Securities and Citi are advising Aon on the transaction, with Cravath, Swaine & Moore handling the legal work.
Subject to regulatory sign-off, the deal is expected to close in the fourth quarter of 2026.
The transaction also stands out for who's selling. USI has spent the better part of a decade under private equity ownership: KKR and Canadian pension giant Caisse de dépôt et placement du Québec bought the firm from Onex Corporation in 2017 for $4.3 billion, including debt. KKR later poured in more than $1 billion of additional capital, becoming USI's largest shareholder – a stake that, at Monday's headline price, has multiplied several times over.
Most of the recent traffic in insurance brokerage M&A has run the other way, with private equity firms snapping up agencies and consultancies rather than selling them to strategics. That makes this deal one of the largest PE exits the sector has seen, and a notable one for KKR, which reported its best-ever quarter for asset sales in the most recent period, at $1.29 billion. Recent exits include its data-center cooling business CoolIT, sold at roughly 15 times the equity KKR put in, and the aerospace and defense unit of pump-and-valve maker Circor. Earlier this year, KKR also closed a $23 billion fund dedicated to private-equity investments in North America, bringing the total raised across the most recent vintages of its flagship regional funds to $46 billion.
For Aon, the move echoes its acquisition of NFP, the middle-market broker it bought from Madison Dearborn Partners and HPS Investment Partners for a deal valued at roughly $13.4 billion when it was announced in December 2023. That transaction reshaped Aon's standing among the world's largest brokers and has continued to generate headlines since, including last year's decision to sell most of NFP's wealth management arm back to Madison Dearborn for roughly $2.7 billion.
That earlier trade signals where Aon believes its edge lies: not in managing individual investors' wealth, but in the corporate risk, employee benefits and institutional retirement work that sits at the center of a middle-market client's balance sheet. USI, whose business overlaps heavily with that description, fits the same thesis.
Once the deal closes, Sicard will be tasked with knitting USI's operations together with NFP and Aon's existing middle-market business under one roof. That integration work will draw scrutiny given what happened the last time around: in June, five specialty executives left Aon's NFP platform for rival Relation Insurance, a departure that industry watchers linked to the retention pressure large consolidations can put on senior producers.
USI's absorption into Aon reshuffles a hierarchy that hasn't moved much at the top in years. Aon currently sits second among US brokers with $16.99 billion in 2025 brokerage revenue, behind Marsh McLennan's $26.66 billion, according to brokerage rankings; USI, at $2.89 billion in 2025 brokerage revenue and nearly 11,000 staff, ranked tenth. Folding USI's revenue into Aon widens the gap Arthur J. Gallagher has been trying to close from third place — a gap Gallagher itself has attacked with acquisitions of its own, closing its $13.45 billion purchase of AssuredPartners in August 2025.
That pattern — big, publicly traded brokers using their stock as currency to buy scale rather than build it organically — has defined the sector for two years now. Describing the trend in a July 2025 analysis of the industry's top 100 brokers, MarshBerry chairman and chief executive John Wepler said publicly traded brokers were effectively taking a "victory lap": years of a depressed share price had kept them from competing with private equity-backed buyers on price, and a stronger stock now gave them the currency to pay full multiples for large, earnings-accretive deals.
That same logic has now played out repeatedly: Marsh McLennan paid $7.75 billion for McGriff Insurance Services in 2024, Gallagher paid $13.45 billion for AssuredPartners, and Brown & Brown paid $9.83 billion for Accession Risk Management last year.
Aon's purchase of USI extends the run and removes one of the few private equity-backed brokers left with the scale to move a public rival's rankings on its own — narrowing the list of similarly sized, independent targets that Marsh McLennan, Gallagher, Brown & Brown, Willis Towers Watson and Lockton might otherwise have been circling themselves.
Aon reported adjusted second-quarter earnings of $3.81 per share on July 29, ahead of analyst estimates, and its stock had a market value of roughly $75 billion as of the Friday before the deal was announced. Shares of Aon rose on Monday following the announcement, while KKR's slipped modestly — a fairly typical reaction for an acquirer taking on new debt to fund a large deal, paired with a seller giving up a long-held, high-performing asset.
The announcement also arrives weeks after Aon's chief financial officer, Edmund Reese, stepped down; the company said he plans to pursue opportunities outside the firm and will continue advising Case through August 2027. A CFO transition landing in the middle of a debt-funded, $17 billion acquisition is the kind of detail investors and analysts will likely press Aon on during Monday's conference call.
