AON

$328.53 71.1B market cap

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Aon plc AON BUFFETT / MUNGER / KLARMAN SUMMARY

1 SNAPSHOT

Price$328.53

Market Cap71.1B

2 BUSINESS

Aon is a capital-light toll booth on global commerce: one of three global insurance and reinsurance brokers earning recurring, inflation-protected commissions and fees on $17.2B of revenue at ~32% adjusted operating margins, with effectively infinite returns on tangible capital and a stated double-digit per-share free-cash-flow growth algorithm. Seth Klarman's new ~4.85% top-five position in Q1 2026 corroborates a durable, recession-resilient compounder bought after an NFP-integration derating. But the margin of safety at $328.53 is thin: my base-case DCF is $325-$352 and the reverse-DCF shows the market already pricing ~7% per-share FCF growth. This is a business to own for twenty years at the right price - so accumulate on weakness toward $300 and back up the truck near $260, rather than chase fair value today.

3 MOAT WIDE

Stable low-30s adjusted operating margins through cycles, commission revenue that inflates automatically with premiums, ~6% organic growth on flat volumes, and 14+ years of ~10%/yr dividend growth

4 MANAGEMENT

CEO: Greg Case (since 2005)

Good-to-Excellent - shrank share count ~12% since 2018, ~10%/yr dividend growth for 14+ years, conservative ~20% FCF payout; the open question is the price paid for NFP ($13B)

5 ECONOMICS

32.4% Op Margin

17.7% ROIC

38.7% ROE

18x P/E

3.22B FCF

173% Debt/EBITDA

6 VALUATION

FCF Yield4.5%

DCF Range290 - 360

Fairly valued - within base-case DCF ($325-$352); market implies only ~7% per-share FCF growth vs a double-digit target

7 MUNGER INVERSION

Kill Event	Severity	P()	E[Loss]
NFP integration disappointment or goodwill impairment ($15.8B goodwill + $5.7B intangibles vs $9.5B equity)	HIGH	-	-
Soft insurance market (premium deflation) compressing organic growth, plus elevated leverage in a higher-rate world	MED	-	-

8 KLARMAN LENS

Downside Case

NFP integration disappointment or goodwill impairment ($15.8B goodwill + $5.7B intangibles vs $9.5B equity)

Why Market Right

Goodwill impairment confirming NFP overpayment; Soft insurance market plus recession compressing organic growth toward zero

Catalysts

Completion of NFP integration restoring reported margin and re-accelerating buybacks above $1.5B/yr; Delivery of double-digit per-share free-cash-flow growth under the final year of the 3x3 Plan; Hard insurance market and premium inflation lifting commission revenue at near-zero incremental cost

9 VERDICT ACCUMULATE

A Quality Moderate-to-Strong - $16.5B debt and $15.3B net debt are notable, but ~6.8x adjusted interest coverage and $3.2B recurring FCF comfortably service it; buybacks paused to delever post-NFP

Strong Buy$260

Buy$300

Fair Value$360

Start a small position only if you want the exposure; build toward full weight at $300 (Accumulate) and add aggressively at $260 (Strong Buy). Trim adds above $370.

🧠 ULTRATHINK Deep Philosophical Analysis

AON - Ultrathink Analysis

The Real Question

The real question is not "is Aon a good business?" — everyone already agrees it is. The real question is subtler and harder: what, exactly, am I paying for when I buy a brokerage oligopolist at fair value, and is the per-share compounding engine more durable than the market's seven-percent assumption?

Most investors treat Aon as a bond-like dividend grower and stop thinking. That is lazy. What you are actually buying is a spread — the gap between the ~9–10% rate at which Aon can compound free cash flow per share (organic growth + margin expansion + a shrinking share count) and the ~7% the market has baked into today's price. If the spread is real, you are buying a 1-in-3 mispricing on one of the most predictable cash machines in the S&P 500. If the spread is an illusion — if NFP permanently lowered the growth algorithm — you are buying a fairly priced bond proxy and your return is the dividend plus inflation. The entire decision collapses to which of those two worlds you believe in.

Hidden Assumptions

The market is making three assumptions I want to interrogate.

Assumption 1: NFP broke the model. The bear sees reported margins falling from 28% to 25% and buybacks frozen and concludes Aon overpaid and diluted its quality. But this conflates accounting with economics. The margin "decline" is intangible amortization — a non-cash ghost. Adjusted operating margin actually rose to 32.4%. The buyback pause is a deliberate deleveraging choice, not a sign of distress. The hidden assumption that "the numbers got worse" is, on inspection, mostly an artifact of purchase accounting.

Assumption 2: Leverage is dangerous. $16.5B of debt looks scary against $9.5B of equity. But equity is a meaningless denominator for a business that buys back so much stock it went negative on book value. The right question is coverage and cash, and ~6.8x adjusted EBIT coverage on $3.2B of recurring FCF is comfortable. The market is anchoring on the wrong balance-sheet ratio.

My own hidden assumption, which I must check: that the insurance-pricing cycle stays benign. I am implicitly assuming premiums keep inflating. If we enter a multi-year soft market, commission revenue stagnates and my 9% growth assumption is too high. This is the assumption most likely to be wrong, and I have priced it by demanding a $300/$260 entry, not by paying $328.

The Contrarian View

For the bears to be completely right, this chain must hold: NFP was a top-of-cycle overpayment that never earns its cost of capital; the middle-market roll-up strategy attracts capital and competition that erodes returns; a prolonged soft insurance market pins organic growth at 3–4%; talent walks out the door with client books because equity comp lost its allure after a flat stock; and the $16.5B debt becomes a refinancing headache in a higher-for-longer rate world. In that world, FCF/share grows ~4% instead of ~9%, the multiple compresses to ~16x, and the stock sits at $260–$280 for years — a dead-money decade.

I take this seriously. The strongest version of the bear case is not "Aon is bad" but "Aon is fine and you overpaid for fineness." That is a real risk at $328 and the precise reason my verdict is WAIT, not BUY.

Simplest Thesis

You are buying a capital-light toll booth on the world's risk, run by disciplined operators who shrink the share count every year — and you only get a great return if you refuse to pay more than ~$300 for it.

Why This Opportunity Exists

The mispricing exists because of a timing mismatch between accounting and economics. Aon swallowed a $13B acquisition in late 2024. Purchase accounting immediately loaded the income statement with intangible amortization (depressing reported margins and EPS) and the balance sheet with goodwill and debt (depressing buybacks and book equity). Screens and headline metrics got uglier at the exact moment the underlying franchise got bigger and more entrenched. Quantitative and momentum money sells the ugly screen; the stock derates from $377 to $315.

This is a structural, recurring source of edge: the market systematically under-weights businesses in the "integration valley" of a transformative deal, because the pain is reported now and the benefit is realized later. Klarman — who has spent forty years buying exactly these accounting-obscured situations — recognizes the pattern. The opportunity persists precisely because it requires the patience to look through three to four quarters of noisy GAAP, and most market participants will not.

What Would Change My Mind

Concrete, falsifiable triggers that would invalidate the thesis:

Organic revenue growth prints below 4% for two consecutive quarters. That breaks the "GDP-plus royalty" premise.
Adjusted operating margin declines year-over-year. The 3x3 Plan's margin-expansion engine would be dead.
Free cash flow per share fails to grow in any full year (ex one-off integration cash costs). This is the number; if it stops compounding, the entire reason to own Aon evaporates.
A goodwill impairment on NFP. That converts "accounting noise" into "real overpayment" and confirms the bear case.
Buybacks remain frozen below $1B/yr beyond 2027 while net-debt/EBITDA stays above ~3x — meaning the deleveraging-then-reacceleration story didn't happen.

If two or more of these fire, I sell regardless of price. None of them are vague worries; each is a line in the next four 10-Qs.

The Soul of This Business

The soul of Aon is accountability without inventory. Strip away the segments and the jargon and you find a business whose entire value is that, when a corporation faces a catastrophe it cannot survive alone, Aon stands between it and the global pool of capital that can absorb the blow — and is trusted to place that risk correctly. It owns almost nothing. It manufactures nothing. Its capital is judgment, data, and a Rolodex built over a century, deployed across 60,000 people in 120 countries.

That is why the moat is inevitable rather than fragile: complex risk is not a commodity that software can disintermediate, because someone must be accountable when the model is wrong and the hurricane is real. The relationship, the data, and the carrier access compound on themselves — more clients yield more data yield better placement yield more clients. The fragility, such as it is, lives entirely on the capital-allocation side: a brilliant operating machine can still be handed to shareholders at a poor return if management overpays for growth. Aon's history says they mostly won't. The stock's price says the market isn't sure. That tension — superb operations, scrutinized allocation, fair price — is the whole investment, and it resolves in your favor only if you have the discipline to wait for $300.

Aon plc (NYSE: AON) — Investment Analysis

Analyst: value-investing workflow | Date: 2026-06-06 | Primary sources: SEC 10-K FY2023–FY2025 (CIK 0000315293), AlphaVantage financial statements, AON earnings transcripts Q2 2025–Q1 2026

Executive Summary

Three-sentence thesis. Aon is one of two-and-a-half global insurance-and-reinsurance brokers that sit between every large corporation and the trillion-dollar capacity of the insurance markets, earning recurring, inflation-protected commissions and fees on roughly $17.2 billion of revenue with ~32% adjusted operating margins and ~13% per-share free-cash-flow growth. The business is capital-light to the point of paradox — Aon has bought back so much stock over a decade that book equity briefly went negative — so returns on tangible capital are effectively infinite and the only real question is the price you pay for the compounding. At $328.53 the stock trades around my base-case fair value of ~$325–$352 (roughly 19x earnings, 22x free cash flow, 4.5% FCF yield), which is fair for a wide-moat oligopolist but not the bargain Aon offered in early 2025 — so this is an ACCUMULATE on weakness / WAIT name, with a Strong-Buy line at ~$260 and an Accumulate line at ~$300.

Metrics Dashboard (FY2025, primary-sourced)

Metric	Value	Source
Price (2026-06-05)	$328.53	historical-prices.json
Market cap	$71.1B	$328.53 × 216.5M shares
Net debt	$15.3B ($16.5B debt − $1.2B cash)	10-K FY2025 balance sheet
Enterprise value	$86.5B	computed
Revenue	$17.18B (+9.4% reported, +6% organic)	10-K FY2025 MD&A
GAAP operating margin	25.3%	income-statement.json
Adjusted operating margin	32.4% (vs 31.5% FY2024)	10-K FY2025 MD&A
Net income	$3.70B	income-statement.json
GAAP EPS (diluted)	~$17.07; TTM $18.21	computed; company-overview.json
Operating cash flow	$3.48B	cash-flow.json
Free cash flow	$3.22B	OCF − $0.26B capex
FCF / share	$14.86	computed
ROE	38.7% (latest); negative-to-high historically due to buyback-driven equity	financial-summary.md
ROIC (book, NOPAT/invested capital)	~17.7%; tangible ROIC ≈ infinite	computed
Interest coverage (adj. EBIT / interest)	~6.8x	computed
Dividend / share	$2.98 annualized ($0.82 declared Q2'26)	dividends.csv
Dividend yield	~0.9%	computed
FCF payout ratio	~20% (dividends) + ~31% (buybacks)	cash-flow.json + 10-K
Employees	~60,000 in 120+ countries	10-K FY2025
Shares outstanding	216.5M (down from 247M in 2018)	balance-sheet.json

The Superinvestor Signal

Seth Klarman's Baupost Group opened a new ~4.85% position in Aon in Q1 2026, making it a top-five holding. That matters for three reasons specific to how Klarman thinks:

Klarman is the patron saint of margin of safety and loss avoidance. He does not chase momentum or stories. A new top-five weight in a fairly valued large-cap broker tells you he sees something durable — most likely the combination of (a) recurring, contractual, inflation-linked revenue that behaves like a royalty on global commerce, and (b) a per-share FCF growth algorithm that the market appears to under-appreciate (the reverse-DCF below shows the price implies only ~7% per-share FCF growth versus Aon's stated double-digit ambition).
He bought after a derating, not before. Aon fell from a 52-week high of $377.57 to the low-$300s (−11.5% one-year return) on NFP-integration noise and a soft 2024. Klarman's edge has always been buying high-quality businesses when a temporary blemish scares the crowd. The blemish here — a $13B acquisition that compressed reported margins and slowed buybacks — is exactly the kind of "this too shall pass" issue he exploits.
The structure suits a long holding period. An oligopoly with pricing power, low capital intensity, and a multi-decade dividend-growth record is a "coffee-can" stock. Klarman rarely trades; he is signalling conviction in a business he can hold through cycles.

I treat this as a strong corroborating signal, not as the thesis. My own work below reaches an independent ACCUMULATE/WAIT verdict on valuation grounds.

The Business (from the 10-K)

Aon is a global professional-services firm organized since 2024 into two reportable segments:

Risk Capital — $11.3B revenue in FY2025 (+7%), comprising:
- Commercial Risk Solutions: insurance brokerage and risk-management consulting (the core "place corporate insurance" business).
- Reinsurance Solutions: reinsurance brokerage, where Aon stands between primary insurers and reinsurers (a true oligopoly — effectively three global players: Aon, Guy Carpenter/Marsh McLennan, and Gallagher Re).
Human Capital — $5.9B revenue in FY2025 (+13%, boosted by NFP), comprising:
- Health Solutions: health-and-benefits brokerage and consulting.
- Wealth Solutions: retirement consulting, pension administration, and investment consulting.

How it makes money. Aon earns commissions (a percentage of the insurance premium it places) and fees (for consulting and administration). Crucially, commission revenue rises with insurance premium inflation even when unit volumes are flat — so a hard insurance market (rising premiums) lifts Aon's revenue at near-zero incremental cost. The business requires almost no physical capital: FY2025 capex was just $263M on $17.2B of revenue (1.5% of sales). The "assets" are 60,000 colleagues, proprietary data, and client relationships.

The 3x3 Plan and "Aon United." Management (CEO Greg Case since 2005) is in the final year of a three-year "3x3 Plan" built on four shareholder metrics: organic revenue growth, adjusted operating margin, adjusted EPS, and free cash flow. The strategy integrates Risk Capital and Human Capital so a single client buys across silos, and uses "Aon Business Services" (a shared-services backbone) to expand margins. Evidence it is working: adjusted operating margin rose from 31.5% to 32.4% in FY2025 with 6% organic growth.

Phase 1 — Risk Analysis (Inversion)

What could permanently impair Aon? I quantify each as P(event over 10y) × severity (peak-to-trough equity impact).

#	Risk	P(10y)	Severity	Expected loss	Notes
1	NFP integration disappoints / goodwill impairment	25%	−15%	−3.75%	$15.8B goodwill + $5.7B intangibles vs $9.5B equity; a write-down dents reported book but not cash flow.
2	Leverage/refinancing strain in a high-rate world	20%	−20%	−4.0%	$16.5B debt; interest expense $0.82B; coverage ~6.8x adj. Manageable but buybacks paused to delever.
3	Regulatory attack on broker commissions / contingent comp	15%	−25%	−3.75%	Recurrent industry risk (cf. 2004–05 Spitzer contingent-commission scandal that hit Marsh).
4	Soft insurance market (premium deflation)	35%	−12%	−4.2%	Cyclical: pricing softens after years of hardening. Hits organic growth, not survival.
5	Disruption: insurtech / direct placement / AI disintermediation	20%	−18%	−3.6%	Low near-term for complex commercial/reinsurance risk; higher for simple SME lines.
6	Talent flight (brokers leaving with books of business)	25%	−10%	−2.5%	People business; non-competes and equity comp mitigate.
7	Macro recession reduces insurable economic activity	40%	−10%	−4.0%	Revenue is resilient (mission-critical), but new-business slows.
8	E&O / litigation from bad advice or placement	20%	−12%	−2.4%	Inherent in brokerage; insured and reserved.
	Sum of independent expected losses			≈ −28%	Non-additive; treat as scenario-weighted, not a single drawdown.

Tail risk (non-additive). The genuinely dangerous combination is a simultaneous soft insurance market + recession + an NFP impairment, which could compress organic growth to zero, force a goodwill charge, and spotlight the $16.5B debt load — a scenario in which the stock could fall 30–40% even though cash flow stays positive. This is a balance-sheet-aware bear case, not a solvency case: even in stress, Aon throws off ~$3B of FCF.

What does NOT threaten Aon: technological obsolescence of the core (complex risk placement is a trust-and-relationship business), commoditization (the top three brokers control the bulk of large-account and reinsurance flow), or capital destruction (there is almost no capital to destroy).

Phase 2 — Financial Analysis

2.1 Revenue and margin trend (10-K + AlphaVantage)

Year	Revenue ($B)	Reported growth	Organic	GAAP op. margin	Adj. op. margin	Net income ($B)
2021	12.19	—	—	17.1%*	~31%	1.26
2022	12.48	+2.3%	+5%	29.4%	~31%	2.59
2023	13.38	+7.2%	+7%	28.3%	~31%	2.56
2024	15.70	+17.3%	+6%	24.4%	31.5%	2.65
2025	17.18	+9.4%	+6%	25.3%	32.4%	3.70

*2021 GAAP margin was depressed by the $1.0B+ Willis Towers Watson merger-termination fee. Adjusted margins have been remarkably stable in the low-30s — evidence of pricing power and operating discipline. The reported-vs-adjusted gap in 2024–25 is intangible amortization from NFP, a non-cash charge.

Revenue CAGR (2021→2025): ~7.1% — and the underlying organic engine runs a steady 5–7% before acquisitions. This is the royalty-on-commerce signature: GDP-plus growth with no commodity or unit-volume cyclicality.

2.2 DuPont / ROE decomposition

ROE is distorted because buybacks drove book equity to negative in 2022–2023 (accumulated deficit from repurchasing stock above book value). This is not distress — it is the mathematical fingerprint of an asset-light compounder returning nearly all cash to owners. As of FY2025, equity recovered to $9.35B (Aon shareholders) after the NFP equity issuance and a year of retention.

The more honest profitability measure is return on invested capital:

Adjusted EBIT FY2025 ≈ 32.4% × $17.18B = $5.57B.
Cash tax rate ≈ 21.2% → adjusted NOPAT ≈ $4.39B.
Invested capital (equity $9.46B + net debt $15.34B) = $24.8B → ROIC ≈ 17.7%.
Strip out goodwill/intangibles ($21.5B of the asset base) and tangible invested capital is negative — tangible ROIC is effectively infinite. The 17.7% book figure is held down only by the price Aon paid for acquisitions, not by the economics of the operating business.

ROIC (17.7%) vs WACC (~8.5–9%). A spread of roughly 9 points on $24.8B of capital = ~$2.2B/yr of economic profit. The operating business itself earns far more than its cost of capital; the swing factor is acquisition discipline.

2.3 Owner earnings & free cash flow

Year	OCF ($B)	Capex ($B)	FCF ($B)	FCF/share
2021	2.18	0.14	2.04	~$9.0
2022	3.22	0.20	3.02	~$13.9
2023	3.44	0.25	3.18	~$15.5
2024	3.04	0.22	2.82	~$13.3
2025	3.48	0.26	3.22	~$14.86

FCF conversion is excellent (FCF ≈ 87% of net income; capex < 2% of revenue). The 2024 dip reflects NFP deal/integration cash costs; 2025 already rebounded. Management explicitly targets double-digit FCF-per-share growth (3x3 Plan), powered by organic growth + margin expansion + buybacks shrinking the share count.

2.4 Capital allocation

Buybacks: $1.0B in both 2024 and 2025 (2.7M shares at avg $365.91 in 2025). Share count fell from 247M (2018) to 216.5M (2025) — a ~12% reduction, ~1.5%/yr tailwind to per-share metrics. Note: buybacks were deliberately reduced post-NFP to delever, and should re-accelerate as leverage normalizes.
Dividend: $2.98/yr, raised ~10%/yr; the Q1 2026 hike to $0.82 (from $0.745) continues a 14+ year growth streak. Payout is a conservative ~20% of FCF.
M&A: NFP (closed Nov 2024, ~$13B) is the big bet — a middle-market platform that extends Aon's reach to smaller clients. Execution risk is real but the strategic logic (distribution + cross-sell) is sound.

2.5 My DCF (FCF-to-equity per share)

Assumptions (explicit): Base FCF/share = $14.86. I model 5 years of growth, then a fade, then a terminal growth rate. Discount rate 9.5–10.5% (Aon's beta is low at 0.71, but I demand a margin-of-safety discount above a pure CAPM rate).

Discount	Bear (6%→4%, term 3.5%)	Base (9%→6%, term 3.5%)	Bull (11%→7%, term 3.5%)
9.5%	$290	$352	$396
10.0%	$267	$324	$364
10.5%	$248	$299	$336

Fair-value range: ~$290–$360, base case ~$325–$352. At $328.53 the stock sits squarely inside the base case — fairly valued, not cheap.

Reverse DCF (the crux). At a 9.5% discount and 3.5% terminal growth, today's $328.53 implies only ~6.8% per-share FCF growth for a decade (~7.9% at a 10% discount). Aon has compounded FCF/share faster than that historically and targets double digits. If management merely delivers ~9% per-share FCF growth, the stock is worth ~$350–$390 and is modestly undervalued. That gap — market pricing ~7%, company targeting ~10% — is, I believe, exactly what Klarman is buying.

2.6 Relative valuation (peers, market multiples only — no analyst inputs)

Metric	Aon	Context
P/E (TTM)	~18–19x	Below its own 5-yr average (low-20s); in line with Marsh McLennan, slightly below the broker group's historical premium.
EV/EBITDA	~16x GAAP / ~15x adj.	Typical for the wide-moat broker oligopoly.
P/FCF	~22x	Reasonable for ~7% organic + buybacks.
FCF yield	4.5%	Fair; 5%+ (≤$300) is where it gets interesting.

The brokerage oligopoly (Marsh McLennan, Aon, Gallagher) consistently commands premium multiples because of the recurring, capital-light, recession-resistant economics. Aon trades at the lower end of that band today, reflecting NFP-digestion concerns — the source of the opportunity.

Phase 3 — Moat Analysis

Moat width: WIDE. Trend: stable-to-widening. Durability: 20+ years.

Aon's moat is a blend of four reinforcing advantages:

Oligopoly scale / cost advantage (the structural moat). Global insurance and especially reinsurance brokerage is a three-firm game. Aon, Marsh McLennan, and Gallagher control the lion's share of large-account and reinsurance placement. Scale begets data; data begets better placement and analytics; better analytics win more clients. A new entrant cannot replicate Aon's 120-country footprint, claims data, or carrier relationships. Metric: #1 or #2 globally in reinsurance and large-commercial brokerage.
Switching costs / embeddedness. Aon is woven into a client's risk-management, benefits, and pension operations. Pension administration and benefits enrollment in particular are sticky, multi-year, mission-critical functions. Retention is consistently high (management cites "strong retention" every quarter). Changing brokers risks coverage gaps on day one — a powerful deterrent.
Trust / brand (the relationship moat). When a CFO places $500M of property-catastrophe cover or designs a pension de-risking transaction, they buy judgment and accountability, not a transaction. Aon's brand is the assurance that the risk is placed correctly. This is why insurtech has barely dented complex commercial/reinsurance brokerage even as it nibbles at simple personal lines.
Data / analytics flywheel. Aon's proprietary analytics (catastrophe modeling, the Jamaica/World Bank cat-bond referenced in the Q3 2025 call) let it structure risk solutions competitors can't, deepening client dependence and pricing power.

Pricing-power evidence: stable low-30s adjusted operating margins through cycles; commission revenue that automatically inflates with premiums; 6% organic growth on flat-ish volumes; the ability to push the dividend up ~10%/yr for over a decade.

What erodes it? A regulatory ban on contingent commissions (manageable — Aon shifted years ago), or a genuine AI-driven disintermediation of complex risk placement (low probability this decade; complex risk is bespoke and accountability-laden). The moat is among the most durable in financial services.

Phase 4 — Decision Synthesis

4.1 Probability-weighted 5-year return tree (from $328.53)

Scenario	P	5-yr price	Annualized (incl. ~1% div)	Contribution
Bull: 10%+ FCF/sh growth, buybacks resume, multiple holds	30%	$520	~10.5%	+3.2%
Base: ~8% FCF/sh growth, fair multiple	45%	$430	~6.5%	+2.9%
Bear: soft market + NFP drag, multiple compresses	20%	$300	~−0.8%	−0.2%
Severe: recession + impairment	5%	$230	~−6%	−0.3%
Weighted expected annualized return				≈ 5.6–6.5%

A high-single-digit expected return for a fortress-quality, low-beta compounder is acceptable but not exceptional — which is precisely why the verdict is ACCUMULATE/WAIT rather than STRONG BUY. The expected return jumps above 9% if you buy ≤$300 (Accumulate) and toward 11–12% ≤$260 (Strong Buy).

4.2 Entry prices

Action	Price	FCF yield	P/FCF	Rationale
Strong Buy	~$260	5.7%	17.5x	Bear-case DCF floor; ~13% projected 5-yr return; clear margin of safety.
Accumulate	~$300	5.0%	20.2x	Lower edge of base case; roughly the price Klarman paid; start building.
Current	$328.53	4.5%	22.1x	Fair value — hold/nibble only.
Trim/avoid-adding	>$370	<4.0%	>25x	Approaches the prior cycle high; reward thins.

4.3 Position sizing

Target 2–4% of portfolio. Quality justifies a real weight; the thin current margin of safety argues for building gradually — a starter now only if you want the exposure, with the bulk reserved for $300 and below.

4.4 Monitoring triggers

Organic revenue growth drops below 4% for two consecutive quarters → moat/cyclical warning.
Adjusted operating margin falls year-over-year → 3x3 Plan stalling / NFP not delivering.
Net debt / EBITDA fails to decline toward ~3x → deleveraging stalled, buybacks stay frozen.
Free cash flow per share fails to grow → thesis broken (this is the number).
Goodwill impairment announced → NFP overpayment confirmed.
Buyback resumption above $1.5B/yr → bullish confirmation that leverage is normalized.

Conclusion

Aon is a textbook Buffett business hiding in plain sight: a capital-light toll booth on global commerce, with a wide oligopoly moat, recurring inflation-protected revenue, ~32% adjusted margins, double-digit per-share FCF-growth ambition, and a fourteen-year dividend-growth record — bought, this quarter, by one of the most loss-averse investors alive. The only thing standing between Aon and a STRONG BUY is the price. At $328.53 it is fairly valued (base-case DCF ~$325–$352; the market implies just ~7% per-share FCF growth versus a double-digit target). I want a bigger cushion. Verdict: ACCUMULATE on weakness toward $300, back up the truck near $260, and hold patiently for the compounding.

Disclaimer: Independent analysis from primary sources only (SEC 10-K filings, company financial statements, earnings-call transcripts). No analyst reports, price targets, or broker research were used as inputs. Not investment advice.