LIVE
AON
Aon plc · Financials - Insurance Brokerage
$317.74
-1.83% this month
VERSUS
⟷
COMPARE
MMC
Marsh & McLennan Companies, Inc. · Financials - Insurance Brokerage & Professional Services
$171.94
-1.22% this month
Scoreboard verdict
Across AI score, momentum, valuation, upside, operating margin
AON
4
MMC
1
Comparison scoreboard
AON LEADS 4/5AI Score
AON ✓50.0
MMC 49.6
1Y Return
AON ✓-9.43%
MMC -25.93%
Fwd P/E
AON ✓15.65
MMC 17.72
Target Up.
AON +14.55%
MMC ✓+15.33%
Op. Margin
AON ✓35.84%
MMC 19.24%
Metrics last refreshed: 6/20/2026
Quick take
AON vs MMC Stock Comparison: AI Score, Valuation, Performance and Upside
AON and MMC (Marsh & McLennan) are the world's two largest global insurance brokerage and professional services firms — Aon focuses on risk, health, and wealth brokerage and advisory with high free cash flow margins, while MMC adds Oliver Wyman strategy consulting and Mercer HR consulting to its Marsh insurance brokerage and Guy Carpenter reinsurance franchise. Both offer high-quality recurring brokerage revenue; MMC has greater consulting diversification.
AON vs MMC is focused risk and insurance brokerage platform (Aon's core risk, health, and wealth brokerage with margin expansion discipline) versus the most diversified insurance brokerage and consulting franchise (Marsh & McLennan's insurance brokerage plus Oliver Wyman and Mercer consulting providing multiple revenue streams across business cycles) — brokerage focus versus conglomerate diversification.
Live analysis · updated 6/20/2026
AON holds the edge across 4 of 5 key metrics in this comparison. AON leads on both 1-year return (-9.43%) and forward P/E (15.65x vs 17.72x for MMC), a relatively favorable combination of momentum and valuation. On fundamentals, MMC is growing revenue faster (11.50%), while AON maintains the higher operating margin (35.84%) — a classic growth-versus-profitability split. Analyst consensus implies similar upside for both: +14.55% for AON and +15.33% for MMC.
Normalized 1Y performance
AON
MMC
Recent returns
AON
MMC
Analyst price targets & sentiment
AON · 19 analysts
STRONG BUYHOLDSTRONG SELL
Buy (2.4/5.0)
Price target range
analyst low$332.65
analyst high$449.00
analyst mean$384.11
current price$317.74
+14.6% upside to analyst mean
MMC
Price target range
analyst mean$210.71
current price$171.94
+15.3% upside to analyst mean
Who should consider this stock?
AON may suit investors who:
- →Want a pure-play global insurance brokerage with Aon's Aon United efficiency program driving margin expansion and strong free cash flow generation from the asset-light commission model
- →Value Aon's integrated risk capabilities across commercial insurance, reinsurance, and employee health and benefits as a comprehensive solution for large multinational corporations
- →Prefer Aon's more focused platform without the management consulting cyclicality that MMC's Oliver Wyman segment introduces
MMC may suit investors who:
- →Want the most diversified global insurance brokerage and professional services platform — Marsh insurance brokerage, Guy Carpenter reinsurance, Mercer HR consulting, and Oliver Wyman strategy consulting in one company
- →Value MMC's multiple revenue streams across different demand cycles — when insurance brokerage is strong, consulting may be softer, and vice versa — reducing overall revenue volatility
- →Appreciate Oliver Wyman's strategy and economic consulting reputation as a top-tier management consultancy alongside the insurance brokerage and HR advisory services
Performance & AI score
| Metric | AON | MMC |
|---|---|---|
| AI score | 50.0 | 49.6 |
| AI rank | #471 | #496 |
| Latest close | $317.74 | $171.94 |
| 1M return | -1.83% | -1.22% |
| 6M return | -9.74% | -13.21% |
| 1Y return | -9.43% | -25.93% |
$10,000 invested — hypothetical growth (dividends reinvested)
How much would $10,000 be worth today if invested at the start of each period, with all dividends reinvested?
| Period | AON | MMC |
|---|---|---|
| 1Y ago | $9.06K (-9.4%) started 2025-06-18 | $7.46K (-25.4%) started 2025-03-18 |
| 5Y ago | $14.34K (+43.4%) started 2021-06-21 | $16.3K (+63.0%) started 2021-03-18 |
| 10Y ago | $34.88K (+248.8%) started 2016-06-20 | $39.62K (+296.2%) started 2016-03-18 |
Hypothetical — past performance does not guarantee future results.
Valuation & upside potential
| Metric | AON | MMC |
|---|---|---|
| Market cap | $71.61B | $89.82B |
| Trailing P/E | 18.41 | 21.93 |
| Forward P/E | 15.65 | 17.72 |
| Price/Sales | 4.90 | N/A |
| EV/Revenue | 4.92 | 4.11 |
| Analyst target | $384.11 | $210.71 |
| Target upside | +14.55% | +15.33% |
Growth, profitability & risk
| Metric | AON | MMC |
|---|---|---|
| Revenue growth | 6.50% | 11.50% |
| Earnings growth | 27.10% | 0.00% |
| EPS growth | +27.10% | 0.00% |
| FCF margin | +19.11% | +17.85% |
| Operating margin | 35.84% | 19.24% |
| Profit margin | 22.54% | 15.60% |
| ROIC proxy | 46.45% | 28.73% |
| Return on equity | 46.45% | 28.73% |
| Dividend yield | 0.98% | 1.97% |
| Beta | 0.71 | 0.75 |
| Debt/equity | 155.05 | 139.50 |
| Current ratio | 1.07 | 1.12 |
| Quick ratio | 0.26 | 0.52 |
Drawdown & downside risk
Lower drawdown and smaller single-period drops generally indicate a smoother ride, though they do not guarantee lower future risk.
1Y risk snapshot
AON max drawdown17.85%
MMC max drawdown30.04%
AON max wkly drop11.49%
MMC max wkly drop9.48%
5Y risk snapshot
AON max drawdown25.38%
MMC max drawdown30.04%
AON max wkly drop12.29%
MMC max wkly drop9.48%
10Y risk snapshot
AON max drawdown38.73%
MMC max drawdown35.80%
AON max wkly drop19.97%
MMC max wkly drop19.03%
Performance metrics by period
| Period | Metric | AON | MMC |
|---|---|---|---|
| 1Y | Growth | -9.43% | -25.69% |
| CAGR | -9.44% | -25.74% | |
| Sharpe ratio | -0.49 | -1.38 | |
| Max drawdown | 17.85% | 30.04% | |
| Max daily drop | 9.27% | 8.52% | |
| Max wkly drop | 11.49% | 9.48% | |
| 5Y | Growth | +39.49% | +53.13% |
| CAGR | +6.89% | +8.90% | |
| Sharpe ratio | 0.21 | 0.31 | |
| Max drawdown | 25.38% | 30.04% | |
| Max daily drop | 9.28% | 8.52% | |
| Max wkly drop | 12.29% | 9.48% | |
| 10Y | Growth | +220.75% | +235.53% |
| CAGR | +12.37% | +12.87% | |
| Sharpe ratio | 0.42 | 0.48 | |
| Max drawdown | 38.73% | 35.80% | |
| Max daily drop | 16.70% | 12.07% | |
| Max wkly drop | 19.97% | 19.03% |
Business comparison
| Category | AON | MMC |
|---|---|---|
| Company | Aon plc | Marsh & McLennan Companies, Inc. |
| Sector | Financial Services | Financial Services |
| Industry | Insurance Brokers | N/A |
| Core business | Aon is a global professional services firm providing risk, health, and wealth solutions — operating as an insurance broker (placing insurance for commercial clients with underwriters), reinsurance broker (Aon Reinsurance Solutions), health consulting and benefits administration, and retirement and investment advisory services. Aon does not take underwriting risk; it earns commissions and fees for placing insurance and providing advisory services. | Marsh & McLennan is the world's largest insurance broker — operating Marsh (insurance and risk management brokerage), Guy Carpenter (reinsurance brokerage), Mercer (human resources and benefits consulting), and Oliver Wyman (strategy, risk, and economic consulting). MMC's consulting subsidiaries provide revenue streams beyond insurance brokerage, differentiating it from pure-play brokers. |
| Investor focus | Investors track Aon's organic revenue growth (excluding acquisitions and currency), adjusted operating margins (Aon has been expanding margins through its Aon United efficiency program), free cash flow, and the failed merger with Willis Towers Watson (blocked by regulators in 2021) that would have created an even larger brokerage giant. | Investors track Marsh & McLennan's organic revenue growth across its insurance brokerage and consulting segments, operating margins (MMC has achieved above 30% adjusted operating margins), Mercer and Oliver Wyman consulting revenue cycles, and capital allocation through acquisitions and buybacks. |
AON strengths
- →Asset-light brokerage model — Aon earns commissions and fees without taking underwriting risk; the insurance brokerage model produces high free cash flow with relatively low capital requirements versus insurers
- →Global scale in complex risk placement — Aon's size enables it to access capacity from the world's largest insurers and reinsurers for complex, hard-to-place risks (catastrophe, cyber, specialty) that smaller brokers cannot handle
- →Integrated risk advisory across commercial insurance, reinsurance, health benefits, and retirement provides large corporate clients with a comprehensive risk management solution from one relationship
MMC strengths
- →Most diversified professional services platform — MMC's Oliver Wyman strategy consulting and Mercer HR consulting provide revenue streams with different cyclical patterns than insurance brokerage commissions, reducing revenue concentration risk
- →Marsh insurance brokerage global leadership — Marsh is the world's largest insurance broker with relationships with the largest corporations, governments, and institutions globally; scale advantages in accessing specialized insurance capacity
- →Mercer's HR and benefits consulting role — as workforce management complexity increases (benefits administration, compensation, global mobility), Mercer's advisory services have consistent demand from large multinational employers
Risks to watch — AON
- →Willis Towers Watson failed merger regulatory overhang — the blocked 2021 merger with WTW was a significant strategic setback; Aon agreed to divest businesses and terminated the merger, paying a $1B breakup fee
- →Revenue tied to insurance pricing cycles — when insurance markets harden (premiums rise) Aon's commission income grows; when markets soften, commission income can compress even if service volume is maintained
- →Competition from Marsh & McLennan and Willis Towers Watson is intensifying globally — all three mega-brokers compete for the same large multinational insurance accounts with differentiated but similar capabilities
Risks to watch — MMC
- →Oliver Wyman consulting is cyclical — management consulting demand contracts during economic downturns when companies cut discretionary spending; Oliver Wyman's strategy consulting revenue can decline meaningfully in recessions
- →High valuation relative to pure-play insurers — MMC trades at a premium to traditional financial companies reflecting its professional services characteristics; any multiple compression could significantly reduce returns for valuation-sensitive investors
- →Competition from Big 4 consulting firms (Deloitte, McKinsey, BCG) in management consulting and from Aon and WTW in insurance brokerage and HR consulting creates multi-front competitive pressure
Frequently asked questions
Free public comparison
Want deeper AI forecasts?
This comparison page is public and free forever. Subscribers can unlock saved watchlists, full AI rankings, detailed forecasts, and interactive analysis tools.
Related comparisons
More comparisons
Browse all 1,000 comparisons →