Aon vs Marsh McLennan
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The short version
- 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 23.6x against 16.7x for Aon.
| Latest fiscal year | AON · FY25 | MRSH · FY25 |
|---|---|---|
| Size | ||
| Market cap | $64.9B | $94.6B |
| 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 | 23.6x |
| Piotroski F-score | 4 | 5 |
Revenue
FY16
AON $9.4B
MRSH $13.2B
FY17
AON $10.0B
MRSH $14.0B
FY18
AON $10.8B
MRSH $15.0B
FY19
AON $11.0B
MRSH $16.7B
FY20
AON $11.1B
MRSH $17.2B
FY21
AON $12.2B
MRSH $19.8B
FY22
AON $12.5B
MRSH $20.7B
FY23
AON $13.4B
MRSH $22.7B
FY24
AON $15.7B
MRSH $24.5B
FY25
AON $17.2B
MRSH $27.0B
AON
MRSH
Operating margin
FY16
AON 19.3%
MRSH 18.4%
FY17
AON 10.7%
MRSH 18.9%
FY18
AON 14.3%
MRSH 18.5%
FY19
AON 19.7%
MRSH 16.1%
FY20
AON 25.1%
MRSH 17.8%
FY21
AON 17.1%
MRSH 21.8%
FY22
AON 29.4%
MRSH 20.7%
FY23
AON 28.3%
MRSH 23.2%
FY24
AON 24.4%
MRSH 23.8%
FY25
AON 25.3%
MRSH 23.1%
AON
MRSH
Free cash flow
FY16
AON $2.2B
MRSH $1.8B
FY17
AON $551M
MRSH $1.6B
FY18
AON $1.4B
MRSH $2.1B
FY19
AON $1.6B
MRSH $1.9B
FY20
AON $2.6B
MRSH $3.0B
FY21
AON $2.0B
MRSH $3.1B
FY22
AON $3.0B
MRSH $3.0B
FY23
AON $3.2B
MRSH $3.8B
FY24
AON $2.8B
MRSH $4.0B
FY25
AON $3.2B
MRSH $5.0B
AON
MRSH
Return on capital
FY16
AON 15.1%
MRSH 17.9%
FY17
AON 6.6%
MRSH 13.9%
FY18
AON 14.4%
MRSH 16.9%
FY19
AON 18.6%
MRSH 11.9%
FY20
AON 22.6%
MRSH 11.5%
FY21
AON 14.2%
MRSH 16.5%
FY22
AON 32.3%
MRSH 15.6%
FY23
AON 33.8%
MRSH 18.4%
FY24
AON 19.2%
MRSH 16.3%
FY25
AON 15.6%
MRSH 15.0%
AON
MRSH
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.