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AON
Aon plc · Financials
$317.74
-1.83% this month
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COMPARE
MMC
Marsh McLennan Companies, Inc. · Financials
$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 Marsh McLennan are the world's two largest insurance brokerage and risk advisory firms — a clear duopoly in global insurance brokerage. Both compete for the same corporate risk management and insurance placement clients. Marsh McLennan's four-brand structure (Marsh, Guy Carpenter, Mercer, Oliver Wyman) provides more business diversification. Aon is slightly more focused on brokerage and reinsurance. Both are exceptional long-term compounders with powerful oligopoly positioning.
AON vs MMC is the focused global insurance and reinsurance brokerage leader with margin expansion potential from operating leverage on organic growth (Aon) versus the world's largest insurance broker with four diversified service brands across brokerage, reinsurance, HR consulting, and management consulting (Marsh McLennan) — focused brokerage excellence vs diversified risk and people advisory franchise.
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:
- →prefer the focused global insurance and reinsurance brokerage with cleaner business model and operating leverage from brokerage scale without management consulting complexity
- →value Aon's reinsurance brokerage leadership and ability to expand organically in reinsurance advisory as global catastrophe risk increases insurance carrier hedging demand
- →want insurance brokerage duopoly exposure at the slightly smaller pure-play peer with potentially more upside from margin improvement on organic revenue growth
- →are comfortable with failed WTW acquisition as permanent lost opportunity, insurance market cyclicality, and reinsurance brokerage concentration in catastrophe-correlated markets
MMC may suit investors who:
- →prefer the world's largest insurance broker with Marsh's negotiating scale, Guy Carpenter's reinsurance breadth, Mercer's HR consulting, and Oliver Wyman's strategic advisory creating multi-business diversification
- →value Marsh McLennan's comprehensive risk and people advisory platform serving as the most complete professional services firm across corporate risk needs
- →want insurance brokerage exposure at maximum scale with management consulting (Oliver Wyman) providing advisory revenue less correlated with pure insurance cycles
- →are comfortable with four-brand management complexity, Oliver Wyman consulting economic sensitivity, and insurance market cycle correlation across brokerage and reinsurance segments
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 one of the world's largest professional services firms, providing insurance brokerage, reinsurance brokerage, human capital consulting, and risk advisory services. Aon's three segments: Commercial Risk Solutions (insurance brokerage), Reinsurance Solutions (reinsurance brokerage for carriers), and Health Solutions (employee benefits consulting). Aon's reinsurance brokerage competes with Guy Carpenter (Marsh subsidiary) in reinsurance advisory for insurance companies. Aon failed to acquire Willis Towers Watson — the deal was blocked by DOJ antitrust in 2021. | Marsh McLennan is the world's largest professional services firm for risk, strategy, and people, operating through four brands: Marsh (insurance brokerage), Guy Carpenter (reinsurance brokerage), Mercer (human capital and investment consulting), and Oliver Wyman (management consulting). Marsh is the world's largest insurance broker by revenue. Together, the four brands provide comprehensive risk advisory and human capital services to global corporations. Marsh McLennan's Oliver Wyman consulting arm adds strategic advisory capabilities beyond pure brokerage. |
| Investor focus | Investors track organic revenue growth, operating margin expansion, free cash flow generation, and share buyback efficiency from Aon's capital return program. | Investors track organic revenue growth across all four brands, Marsh insurance brokerage market share, Mercer investment consulting assets under advisement, and operating margin improvement. |
AON strengths
- →Reinsurance market leadership: Aon Re (reinsurance brokerage) is a top-2 global reinsurance broker — essential for insurance companies purchasing risk protection from reinsurers
- →Sticky advisory relationships: Aon's corporate clients rely on Aon for renewal of insurance programs, employee benefits design, and risk management — multi-year relationships with significant switching costs
- →Operating leverage from scale: Aon's global brokerage scale allows margin expansion as revenue grows without proportional cost increases
MMC strengths
- →World's largest insurance broker: Marsh's scale creates negotiating power with insurers, data advantages for pricing benchmarks, and specialized industry expertise depth that smaller brokers cannot replicate
- →Four-brand diversification: Marsh (brokerage), Guy Carpenter (reinsurance), Mercer (HR consulting), and Oliver Wyman (management consulting) create revenue streams across business and economic cycles
- →Oliver Wyman consulting provides high-margin advisory revenue less correlated with insurance market cycles — diversifying from pure brokerage earnings
Risks to watch — AON
- →Failed Willis Towers Watson acquisition removed a transformative growth opportunity — Aon's organic growth must compensate for the deal's strategic rationale that was blocked
- →Insurance market hardening benefits brokerage (higher premiums = higher commissions) but also means clients pay more — in soft markets, commission income declines
- →Reinsurance brokerage concentration makes Aon's revenue somewhat correlated with catastrophe events and reinsurance pricing cycles
Risks to watch — MMC
- →Oliver Wyman consulting revenue is more economically sensitive — management consulting demand declines during corporate cost-cutting
- →Marsh and Guy Carpenter insurance and reinsurance brokerage revenue correlates with premium volumes — soft insurance markets compress commission income
- →Integration complexity across four distinct service brands requires careful management to maintain brand differentiation while realizing cross-sell synergies
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