Aon (AON) Stock Looks Reasonable Even With A 17% Jump

Aon shares have surged over the past month, and that rapid shift puts fresh attention on whether the business is earning enough on its capital to support the current price. With the stock now back in focus after a mixed year of returns, the question is how far those underlying economics really stretch.

• The share price has climbed 16.6% in the past month, which puts more weight on whether recent buyers are paying a level that the company’s returns on capital can support over time.
• Fresh growth in Aon’s core risk, health, and wealth activities, alongside plans to absorb USI Insurance Services, can reshape how efficiently the group invests its balance sheet and how much excess return it can generate on that capital base.
• What if you looked at Aon through its earnings instead? See why Aon's 17.4x P/E tells a different valuation story.

For investors, the debate is whether Aon’s current share price is adequately supported by the returns the business earns on the capital it invests.

If you want to test the same question about the returns a business earns on its capital across a wider field, line Aon up alongside the 30 high quality undervalued stocks.

Is Aon Still Cheap on Excess Returns?

The Excess Returns model looks at how much profit Aon generates over and above the return investors typically demand on its equity. On this view, Aon is modeled with a Book Value of $47.60 per share and a Stable Book Value of $63.10 per share, while analysts expect Stable EPS of $18.94 per share. The implied Average Return on Equity of 30.02% sits well above the modeled Cost of Equity of $4.83 per share, creating an Excess Return of $14.11 per share in the model.

Because those modeled returns remain higher than the assumed cost of capital, the Excess Returns framework puts Aon’s estimated intrinsic value meaningfully above the current share price of $321.64. The reported Q3 2026 results and the planned USI acquisition help explain why the model assumes the firm can keep earning more than its equity cost over time, even as the market still prices the shares below what those modeled returns support. To see how that gap is quantified in detail, compare this Excess Returns view with the full intrinsic worth output for Aon. Find out what Aon could be worth using our Excess Returns estimate.

The Aon Narrative: What Would Justify Today's Price?

Narratives pick up where the excess returns puzzle leaves off. They explain which paths for Aon’s growth, margins and earnings would need to occur for the stock to be worth meaningfully more or less than today’s price. Each Narrative links its number to a clear view on how Aon’s growth, profitability and risks might evolve, giving you something concrete to revisit as fresh information becomes available. These are available on Simply Wall St’s Community page.

The community is split on Aon, with one camp seeing more long term earnings power in the USI deal and another focusing on integration strain and higher debt.

Bull case: 9% undervalued

"Management’s plan to combine Aon, NFP and USI into a US$6.5b revenue U.S. middle market platform, focused on an addressable commercial P&C opportunity of more than US$40b across over 200,000 companies…"

Discover why this Narrative puts Aon at 9% undervalued.

Bear case: 24% overvalued

"Although Aon is targeting detailed USI revenue and cost synergies, the planned US$160 million of transaction costs, US$550 million of integration costs through 2028, up to US$400 million of retention spending and the built-in US$60 million of revenue leakage create a long tail of cash outflows…"

Explore why this Narrative puts Aon at 24% overvalued.

Aon’s price is only one piece of the decision

Before you stop at what Aon earns on its capital, you also need to look at who is steering the business, what they are paid for, and how their rewards line up with your interests. See who runs Aon and how they are paid.

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