Aon Outlook Revised to Negative Amid USI Acquisition Debt
S&P Global Ratings announced on 1 September 2026 that it has changed Aon PLC’s (NYSE:AON) outlook from stable to negative, while affirming the issuer’s A‑ credit rating. The outlook downgrade reflects S&P’s concern that Aon’s leverage will remain elevated after it completes its planned acquisition of U.S. middle‑market broker USI Inc.
Aon has signed a definitive agreement to acquire USI Inc. from its current financial‑sponsor owners KKR & Co. Inc. and La Caisse. The transaction is expected to close on 31 December 2026 and will be financed with $17.5 billion of new debt. The debt package includes a $4.0 billion term loan and $13.5 billion of senior notes with staggered maturities, of which $1.3 billion is earmarked to pre‑fund maturities that fall in the first half of 2027.
S&P projects that Aon’s pro‑forma financial leverage will rise to 4.3‑4.5× after the acquisition, a level that is materially higher than the company’s run‑rate expectations and above the leverage metrics of its key peers. The agency notes that, despite this near‑term increase, it expects a gradual improvement in leverage through 2028 driven by revenue and earnings growth, debt repayment, and reduced discretionary spending, including a curtailment of share‑buyback programmes.
USI Inc. is identified by Business Insurance magazine as the 10th‑largest insurance broker of U.S. business in 2026. Its revenue is roughly 15 % of Aon’s stand‑alone revenue, making the deal Aon’s largest‑ever acquisition and a strategic move to deepen its scale in the U.S. middle‑market segment—a market where Aon already has a material presence following its 2024 acquisition of NFP Corp.
S&P warns that if Aon’s stand‑alone business, the acquisition, or its financial‑policy decisions underperform, the agency could lower the credit rating within 24 months. Conversely, the outlook could be upgraded back to stable within 24 months if Aon meets the stipulated deleveraging targets or if the transaction is cancelled.