AJG vs AON: Which Is the Better Buy in 2026?
Last updated August 2026
Short answer
AJG (Arthur J. Gallagher) and AON (Aon plc) share investment themes but are different businesses. The right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme.
AJG vs AON: the tie-breaker metrics
Same yardstick, side by side (as of August 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.
| Metric | AJG | AON | What it tells you |
|---|---|---|---|
| Forward P/E | 16.78 | 16.88 | Valuation on next year's expected earnings, the same yardstick for both. Lower is cheaper for that growth; higher means the market is paying up. |
| Trailing P/E | 41.29 | 19.88 | Valuation on the last 12 months. A big drop from trailing to forward means the market expects earnings to jump, so more growth is already in the price. |
| Beta | 0.51 | 0.70 | Volatility vs the market. Above 1 swings harder than the index; below 1 is steadier. Higher beta means bigger drawdowns to hold through. |
| Price vs 52-week range | 48% of range | 72% of range | Where today's price sits between the 52-week low and high. Near the high is momentum with less margin of safety; near the low is out of favor or a discount, depending on why. |
| Price / book | 2.70 | 7.96 | How much you pay over book value. Very high can signal an asset-light, high-return business or a rich price. |
Before you buy: how AJG and AON affect your concentration
The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. AJG and AON share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.
This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined AJG and AON exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.
What does Arthur J. Gallagher (AJG) do?
Arthur J. Gallagher & Co. is a global insurance brokerage, risk management, and consulting firm, ranking as the third-largest publicly traded insurance broker behind Marsh & McLennan and Aon. Its Brokerage segment places property, casualty, employee benefits, wholesale, and reinsurance coverage for businesses and institutions, earning commissions and fees, while its Risk Management segment (Gallagher Bassett) handles third-party claims administration. The company runs an asset-light, fee-and-commission model that generates strong free cash flow, and it has built a decades-long track record of growing by acquiring smaller regional brokers and folding them into its platform.
What does Aon plc (AON) do?
Aon plc is one of the world's leading brokers and professional-services firms in risk and human capital. It arranges insurance and reinsurance for corporate clients, advises on risk management and analytics, and provides health, benefits, retirement, and talent consulting. The company organizes its work around two broad solution lines, Risk Capital (commercial risk and reinsurance brokerage and related advisory) and Human Capital (health, benefits, wealth, and talent). Crucially, Aon is an intermediary and advisor: it earns commissions and fees rather than underwriting insurance itself, so it does not carry the catastrophe-loss risk that insurers do, which gives its revenue a recurring, relatively defensive quality.
AJG vs AON: how do they differ?
Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.
- AJG drivers: Acquisition-led compounding; AssuredPartners integration and synergies.
- AON drivers: Steady organic growth; Margin expansion and Aon United.
Which fits which kind of investor
A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: The most cited concern is valuation, as AJG often trades at a large premium to the broader insurance sector and to some peers, leaving little room for disappointment. For AON, the most discussed risk is valuation: Aon trades at a premium multiple, so disappointing organic growth, margin, or integration results could compress its multiple even if the business remains sound.
AJG or AON: which should you pick?
AJG vs AON: the full fundamentals
AJG. AJG reported roughly 28% total revenue growth in Q1 2026, blending about 5% organic growth with large contributions from acquisitions including AssuredPartners. The stock's trailing P/E in the mid-30s to around 40x sits well above the broader insurance industry average, a premium the market has historically assigned to its consistency. Forward multiples look lower on expected earnings growth, but the shares clearly price in continued execution.
AON. These figures are approximate and tied to the asOf date; verify live numbers before acting. Aon is valued as a high-quality compounder, so its premium multiple reflects durable organic growth and margin expansion rather than cheapness. The key question for most investors is whether that consistency justifies the price, and whether NFP integration and organic growth keep supporting the multiple.
Headline figures (approximate, July 2026): AJG shows market cap ~$56 billion, revenue (ttm) ~$13 billion, q1 2026 revenue ~$4.76 billion, q1 2026 adjusted eps ~$4.47; AON shows revenue trend Mid-single-digit organic revenue growth, with total revenue boosted by the NFP acquisition, earnings direction Rising earnings per share in 2026, supported by margin expansion and buybacks, margins Adjusted operating margins in the low-30s percent, with guidance for continued basis-point expansion, business model Fee-and-commission broker and advisor; does not underwrite insurance, so revenue is recurring and defensive.
The bottom line: AJG vs AON
AJG and AON are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined AJG and AON exposure against your real portfolio. It is not an investment adviser.
Wondering how AJG or AON fits the portfolio you already own? Walnut is an AI investing app that connects your brokerage read-only and answers questions like that about your actual holdings: overlap, concentration, and how each position tracks the S&P 500. Compare the best AI portfolio analyzers or see the best AI investing apps in 2026.
Investing in Arthur J. Gallagher with AI
Connect the broker you already use and ask Walnut's AI how AJG fits what you actually hold: whether you own it already through a fund, what it would do to your concentration, and how it has tracked the S&P 500. Read-only by default, and you approve anything before it reaches your broker.
FAQ
What is the difference between AJG and AON?
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Arthur J. Aon plc is one of the world's leading brokers and professional-services firms in risk and human capital. They show up together because they share investment themes, but they are different businesses, so the better fit depends on which thesis you are expressing.
Is AJG or AON the better stock?
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Neither is universally better; they suit different views and risk levels. Walnut is informational, not investment advice. Compare what each does, the tie-breaker metrics above, and the risks, then decide which fits your thesis and what you already own.
Which is cheaper, AJG or AON?
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On forward P/E (as of August 2026), AJG trades at 16.78x and AON at 16.88x, so AJG is the cheaper of the two on next year's expected earnings. A lower multiple is not automatically the better buy: a richer valuation can be justified by faster growth, and a lower one can reflect real risk. Weigh the multiple against how fast each business is compounding.
Should you own both AJG and AON?
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Because they share themes, owning both concentrates you in that theme. That can be intentional (a focused bet) or accidental (less diversification than it looks). Walnut can show your combined exposure across both, and whether adding either over-concentrates you, before you buy.
What are the risks of AJG vs AON?
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AJG: The most cited concern is valuation, as AJG often trades at a large premium to the broader insurance sector and to some peers, leaving little room for disappointment. Larger acquisitions such as AssuredPartners carry integration, cultural, and technology-system risk that could delay synergies. Softening property insurance pricing could trim organic growth by up to about a percentage point if it continues. Regulatory scrutiny is a growing factor, including Department of Justice attention to roll-up M&A strategies and new federal rules requiring more granular disclosure of broker commissions. Benefits-related exposure to Medicare Advantage payment rates and general economic sensitivity of client exposures round out the risk set. AON: The most discussed risk is valuation: Aon trades at a premium multiple, so disappointing organic growth, margin, or integration results could compress its multiple even if the business remains sound. Insurance-brokerage revenue is tied to commercial insurance pricing (the property-and-casualty rate cycle) and to client business volumes, so a soft market or weaker economy could slow growth. Integrating NFP carries execution and talent-retention risk, and acquisitions add goodwill and debt. As a global firm, Aon faces currency swings, regulatory and litigation exposure across many jurisdictions, and competition for producers from rivals and private-equity-backed brokers. Rising interest expense on its debt and any loss of key client relationships would also pressure results. None of these are catastrophe-underwriting risks, but they can still slow a premium compounder.
Walnut is informational, not investment advice. This page is descriptive and not a recommendation to buy or sell AJG or AON; figures are approximate and dated (as of August 2026). Verify current data before investing.