Aon

Aon is the insurance brokerage that Warren Buffett spent 2023-2024 quietly accumulating during the NFP-acquisition uncertainty. Berkshire's first AON disclosure was Q4/2024 at 4.1M shares (~$1.3B). As of Q1/2026, Berkshire holds 7.8M shares (~$2.4B value), with the most recent add of 1.2M shares in Q4/2025 at an average price of $338. Buffett does not buy insurance brokers — except this one, and it tells you something about the moat.

The 2026 story is the NFP integration plus the hard insurance market entering Year 5. Aon completed the $13B NFP acquisition in April 2024, adding middle-market commercial insurance brokerage capabilities. Q1/2026 organic revenue growth was +6%, with NFP-specific synergies running ahead of the original $175M target — management now guides $250M+ by 2027. The combined entity processes $750B+ in annual insurance premium flow.

The unappreciated business is Aon's wealth solutions and human-capital advisory. These two non-brokerage segments grew +9% in Q1/2026 at 35%+ operating margins. Aon now derives 47% of revenue from advisory services (not pure brokerage commissions) — a margin and stability advantage that Marsh McLennan and Willis Towers Watson have not matched at the same scale.

Berkshire Hathaway built the Aon position over Q4/2024 through Q4/2025 — five consecutive quarters of additions, no trims. The cost basis sits around $295 per share against a current price of $313 (6% gain plus dividends). This is one of only two Berkshire positions where Buffett added in every single quarter of 2025 (the other was Occidental Petroleum). Berkshire's 7.8M-share position represents 3.2% of Aon's total shares outstanding.

Other notable smart-money: Akre Capital (Chuck Akre's fund) holds 1.1M shares — unchanged for 4 years. Capital Group added 5.5M shares net in Q1/2026 (8% of position). Pershing Square (Ackman) added 1.8M shares in Q3/2025 at $325 — a notable new Pershing position. The smart-money consensus is 'quality-compounder accumulation', not catalyst trading.

Insider activity (Form 4): CEO Greg Case sold 175,000 shares in February 2026 at $361 (routine 10b5-1 plan, his standard quarterly disposition). CFO Edmund Reese sold 65,000 shares at the same time. No insider buying in the past 18 months — but Aon insiders historically don't make open-market buys, so this carries less weight than an absence of buying at TransDigm or Pfizer.

Aon trades at a forward P/E of 14.6× and EV/EBITDA of 13× as of May 2026. Comparable peers: Marsh McLennan (20×), Willis Towers Watson (17×), Arthur J. Gallagher (23×), Brown & Brown (28×). The bull case (Wells Fargo, JP Morgan) values Aon at $430-435 based on full NFP synergies plus 47%-advisory mix expansion to 55% by 2028. The bear case (Citi) at $298 assumes hard-market reversal compresses commissions and slows EPS growth to 5%. Wall Street analyst targets range from $298 (Citi) to $436 (Wells Fargo), median $387 vs. current $313 — 24% upside before the 1.1% dividend.

1. July 24, 2026: Q2/2026 earnings — organic revenue growth must exceed 6% to support the bull thesis
2. November 2026: Q3/2026 earnings + 2027 guidance — first formal management view on the synergy uplift to $250M+
3. February 2027: Investor Day — management framework on advisory-revenue migration path from 47% to 55% by 2028

Aon is the cleanest 'Buffett accumulating in plain sight' setup in the market right now. The five-consecutive-quarter add pattern is statistically rare — and Buffett does not buy insurance brokers, except this one. At $313 today, the forward P/E of 14.6× is not the deep-value entry Berkshire's older holdings were, but it sits well below the peer group of 17-23×. I hold AON at 3% of my portfolio with an active-add zone below $290 (forward P/E 13.5, peer-discount widening to 8 points). The hard-market reversal in 2027-2028 is the real risk — but Aon's 47% advisory mix absorbs more of that hit than Marsh McLennan can. The NFP integration story plays out through 2027 regardless of insurance cycle.