Aon vs Marsh McLennan
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KIRA’s take AI analyst
I put Aon and Marsh McLennan side by side, using each one’s latest annual report. Here is what stands out:
- Marsh McLennan is the larger business, with $27.0B of revenue in fiscal 2025 against $17.2B for Aon, about 1.6 times as much.
- Marsh McLennan grew revenue faster (10.3%, against 9.5%).
- Aon kept more of each dollar of sales as operating profit (25.3% operating margin, against 23.1%).
- Aon earned a higher return on the capital invested in it (15.6%, against 15.0%).
- Investors pay more for each dollar of Marsh McLennan’s earnings: a P/E of 23.3x against 16.7x for Aon.
Who comes out ahead
Of the 10 measures where higher (or lower) is clearly better, how many each company leads.
Aon
AON
5/10
Operating marginNet marginFCF marginReturn on capitalReturn on equity
Marsh McLennan
MRSH
5/10
Revenue growth5-year growthPiotroski F-scoreNet debt / EBITDAShare count change
Side by side
Best in the row
| Latest fiscal year | AON FY25 | MRSH FY25 |
|---|---|---|
| Size | ||
| Market cap | $64.6B | $93.3B |
| Revenue | $17.2B | $27.0B |
| Free cash flow | $3.2B | $5.0B |
| Net income | $3.7B | $4.2B |
| Growth | ||
| Revenue growth | 9.5% | 10.3% |
| 5-year growth | 9.2% | 9.4% |
| Share count change | 2.2% | −0.4% |
| Profitability | ||
| Gross margin | — | — |
| Operating margin | 25.3% | 23.1% |
| Net margin | 21.5% | 15.4% |
| FCF margin | 18.7% | 18.5% |
| Return on capital | 15.6% | 15.0% |
| Return on equity | 47.8% | 28.8% |
| Balance sheet | ||
| Net debt | $12.5B | $16.9B |
| Net debt / EBITDA | 2.8x | 2.6x |
| Dividends and buybacks | $1.6B | $3.7B |
| Valuation & quality | ||
| P/E | 16.7x | 23.3x |
| Piotroski F-score | 4 | 5 |
Ten years
Revenue
Operating margin
Free cash flow
Return on capital
Each company's latest fiscal year; fiscal years end in different months. The best value in each row is highlighted where higher (or lower) is clearly better. Not investment advice.