Aon is reportedly closing in on a deal to buy USI Insurance Services from KKR for about $17 billion including debt, a transaction that could be announced as soon as Monday, August 31. If finalized, the deal would rank as Aon's second multibillion-dollar acquisition of a middle-market insurance brokerage in under three years, following its 2024 takeover of NFP Corp.
The Wall Street Journal reported that Aon is close to an agreement to acquire USI, according to the New York Post, which cited the Journal's account of the deal terms. Per that report, negotiations must still be successfully concluded before any announcement goes out. Aon could not be reached for comment, and USI Insurance Services also could not be reached, the Post noted; KKR declined to comment, while Reuters said it could not immediately verify the acquisition report.
Aon is headquartered in London, while USI is based in Valhalla, New York. KKR, based in New York City, is USI's largest shareholder. The acquisition is expected to boost USI's capabilities in helping midsize businesses and, per the report, is expected to increase USI earnings per share as soon as 2028.
How USI Ended Up in KKR's Portfolio
KKR and Caisse de dépôt et placement du Québec originally acquired USI from Onex Corporation in 2017 for $4.3 billion including debt, according to the Post's reporting. KKR later deepened its position, investing more than $1 billion additionally in USI as it built toward becoming the firm's largest shareholder. Separately, according to the Caisse de dépôt et placement du Québec, KKR made a follow-on equity investment of more than $1 billion in September 2023 to acquire shares from co-investor CDPQ, formally making KKR the majority shareholder.
A $17 billion enterprise valuation would mark nearly a fourfold increase over the $4.3 billion price KKR and CDPQ paid for USI in 2017, per Coverager. During its nine years under private equity ownership, USI grew from 4,400 employees across 140 offices to more than 10,500 professionals across nearly 200 U.S. locations, the outlet reports.
A Bigger Brokerage, a Narrower Gap With Marsh McLennan
Based on USI's reported annual revenue of roughly $3 billion, a $17 billion valuation implies an acquisition multiple of about 5.7 times sales, according to Investing.com. AM Best's global broker rankings, published in July based on 2025 revenue data, placed USI 13th among the world's largest insurance brokerages with $2.97 billion in total revenue, as reported by Atlas Magazine. That same ranking put Marsh McLennan atop the industry with $26.98 billion in revenue, followed by Aon in second place with $17.20 billion — meaning a USI acquisition would narrow the gap between the two giants.
The broader market backdrop is expanding too. Global industry research from Global Market Insights estimated the worldwide insurance brokers and agents market at $276.5 billion in 2025, projecting growth to $299.6 billion in 2026 and a compound annual growth rate of 9.1% through 2035.
Aon's Recent Moves to Clear the Way
The USI pursuit follows a period of active portfolio reshuffling at Aon. The company completed its acquisition of property and casualty broker NFP Corp. in April 2024 for an estimated $13.4 billion, funded with $7 billion in cash and $6.4 billion in Aon stock, according to a company announcement carried by PR Newswire. Aon had bought NFP from Madison Dearborn Partners and HPS Investment Partners to deepen its middle-market footprint.
In October 2025, Aon completed the sale of a significant majority of NFP's wealth management business back to Madison Dearborn Partners for $2.7 billion, generating roughly $2.2 billion in after-tax cash proceeds, per PLANADVISER. That divestiture freed up capital and sharpened Aon's focus on core commercial risk and employee benefits brokerage ahead of any pursuit of USI. On the seller's side, KKR's other recent exits include the sale of CoolIT and the commercial and defense aerospace unit of CIRCOR, per the Post's report.
The Antitrust Shadow From 2021
Any USI deal will likely draw comparisons to Aon's failed attempt to merge with Willis Towers Watson in a $30 billion transaction that collapsed in July 2021. The U.S. Department of Justice filed a civil antitrust lawsuit to block that combination, arguing it would reduce competition and raise prices for commercial risk and health benefits broking, and the two companies mutually terminated the agreement rather than fight the suit, according to the Justice Department's own announcement at the time. While the USI transaction targets middle-market clients rather than the largest multinational corporations, the memory of that blocked megamerger means regulators may still take a close look at how combining Aon's NFP business with USI affects competition for midsize American businesses. Whether that scrutiny materializes, and how it might shape the deal's terms or timeline, remains an open question pending any formal announcement.
