AON vs AJG

For growth investors, Arthur J.

Gallagher & Co. (AJG) is the stronger pick with 20. 7% revenue growth year-over-year, versus 9. 4% for Aon plc (AON). Aon plc (AON) offers the better valuation at 18. 4x trailing P/E (16. 5x forward), making it the more compelling value choice. Analysts rate Aon plc (AON) a "Buy" — based on 38 analyst ratings — the highest consensus in this comparison. The "better buy" depends entirely on your goals: growth investors should weight revenue trajectory, value investors should weight P/E and PEG, and income investors should weight dividend yield and streak.

On trailing P/E, Aon plc (AON) is the cheapest at 18.

4x versus Arthur J. Gallagher & Co. at 35. 1x. On forward P/E, Arthur J. Gallagher & Co. is actually cheaper at 15. 3x — notably different from the trailing picture, reflecting expected earnings growth. The PEG ratio (P/E divided by earnings growth rate) is the most growth-adjusted single valuation metric: Aon plc wins at 1. 10x versus Arthur J. Gallagher & Co. 's 2. 35x — a reasonable growth-adjusted valuation.

Over the past 5 years, Arthur J.

Gallagher & Co. (AJG) delivered a total return of +41. 1%, compared to +26. 2% for Aon plc (AON). Over 10 years, the gap is even starker: AJG returned +372. 4% versus AON's +219. 8%. Past returns do not guarantee future results, and the stock with the higher historical return may already have its best growth priced in.

By beta (market sensitivity over 5 years), Arthur J.

Gallagher & Co. (AJG) is the lower-risk stock at 0. 09β versus Aon plc's 0. 10β — meaning AON is approximately 11% more volatile than AJG relative to the S&P 500. On balance sheet safety, Arthur J. Gallagher & Co. (AJG) carries a lower debt/equity ratio of 60% versus 173% for Aon plc — giving it more financial flexibility in a downturn.

By revenue growth (latest reported year), Arthur J.

Gallagher & Co. (AJG) is pulling ahead at 20. 7% versus 9. 4% for Aon plc (AON). On earnings-per-share growth, the picture is similar: Aon plc grew EPS 36. 3% year-over-year, compared to -11. 9% for Arthur J. Gallagher & Co.. Over a 3-year CAGR, AJG leads at 17. 7% annualised revenue growth. Higher growth typically commands a higher valuation multiple — check whether the premium P/E or P/S is justified by the growth rate using the PEG ratio.

Aon plc (AON) is the more profitable company, earning 21.

5% net margin versus 10. 7% for Arthur J. Gallagher & Co. — meaning it keeps 21. 5% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: AON leads at 25. 3% versus 18. 3% for AJG. At the gross margin level — before operating expenses — AJG leads at 54. 8%, reflecting greater pricing power or product mix advantage. Stronger margins indicate durable pricing power, lower cost of revenue, or higher mix of software/services. They are one of the clearest signs of business quality.

The PEG ratio (forward P/E divided by expected earnings growth rate) is the most precise measure of undervaluation relative to growth potential.

By this metric, Aon plc (AON) is the more undervalued stock at a PEG of 1. 10x versus Arthur J. Gallagher & Co. 's 2. 35x. A PEG below 1. 5 suggests fair-to-attractive pricing relative to expected growth. On forward earnings alone, Arthur J. Gallagher & Co. (AJG) trades at 15. 3x forward P/E versus 16. 5x for Aon plc — 1. 2x cheaper on a one-year earnings basis. Analyst consensus price targets imply the most upside for AJG: 35. 9% to $274. 38.

All stocks in this comparison pay dividends.

Arthur J. Gallagher & Co. (AJG) offers the highest yield at 1. 3%, versus 0. 9% for Aon plc (AON).

For long-horizon retirement investors, Arthur J.

Gallagher & Co. (AJG) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (low volatility (β 0. 09), 1. 3% yield, +372. 4% 10Y return). Both have compounded well over 10 years (AJG: +372. 4%, AON: +219. 8%), confirming both are viable long-term holds — but the lower-volatility option typically results in less emotional selling during corrections. Retirement portfolios generally favour predictability over maximum returns. Consult a financial advisor before making allocation decisions.

Both stocks operate in the Financial Services sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both.

In terms of investment character: AON is a mid-cap quality compounder stock; AJG is a mid-cap high-growth stock. These fundamental differences mean investors should not choose between them on a single metric — the "better stock" depends entirely on which of these characteristics aligns with your investment strategy.