AIR vs HEI vs TDG vs KAI

For growth investors, AAR Corp.

(AIR) is the stronger pick with 19. 9% revenue growth year-over-year, versus -0. 1% for Kadant Inc. (KAI). TransDigm Group Incorporated (TDG) offers the better valuation at 38. 7x trailing P/E (32. 0x forward), making it the more compelling value choice. Analysts rate AAR Corp. (AIR) a "Buy" — based on 20 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, TransDigm Group Incorporated (TDG) is the cheapest at 38.

7x versus AAR Corp. at 336. 4x. On forward P/E, AAR Corp. is actually cheaper at 24. 1x — 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: TransDigm Group Incorporated wins at 1. 03x versus HEICO Corporation's 3. 14x — a reasonable growth-adjusted valuation.

Over the past 5 years, AAR Corp.

(AIR) delivered a total return of +191. 8%, compared to +86. 8% for Kadant Inc. (KAI). Over 10 years, the gap is even starker: HEI returned +823. 0% versus AIR's +399. 6%. 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), TransDigm Group Incorporated (TDG) is the lower-risk stock at 0.

79β versus AAR Corp. 's 1. 64β — meaning AIR is approximately 108% more volatile than TDG relative to the S&P 500. On balance sheet safety, Kadant Inc. (KAI) carries a lower debt/equity ratio of 38% versus 86% for AAR Corp. — giving it more financial flexibility in a downturn.

By revenue growth (latest reported year), AAR Corp.

(AIR) is pulling ahead at 19. 9% versus -0. 1% for Kadant Inc. (KAI). On earnings-per-share growth, the picture is similar: HEICO Corporation grew EPS 33. 5% year-over-year, compared to -72. 9% for AAR Corp.. Over a 3-year CAGR, HEI leads at 26. 6% 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.

TransDigm Group Incorporated (TDG) is the more profitable company, earning 23.

5% net margin versus 0. 4% for AAR Corp. — meaning it keeps 23. 5% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: TDG leads at 47. 2% versus 6. 7% for AIR. At the gross margin level — before operating expenses — TDG leads at 60. 1%, 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, TransDigm Group Incorporated (TDG) is the more undervalued stock at a PEG of 1. 03x versus HEICO Corporation's 3. 14x. A PEG below 1. 5 suggests fair-to-attractive pricing relative to expected growth. On forward earnings alone, AAR Corp. (AIR) trades at 24. 1x forward P/E versus 51. 6x for HEICO Corporation — 27. 5x cheaper on a one-year earnings basis. Analyst consensus price targets imply the most upside for TDG: 30. 3% to $1617. 88.

In this comparison, TDG (13.

3% yield), KAI (0. 4% yield) pay a dividend. AIR, HEI do not pay a meaningful dividend and should not be held primarily for income.

For long-horizon retirement investors, TransDigm Group Incorporated (TDG) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (low volatility (β 0.

79), 13. 3% yield, +595. 3% 10Y return). AAR Corp. (AIR) carries a higher beta of 1. 64 — meaning larger drawdowns in market downturns, which matters significantly when you cannot wait years for a recovery. Both have compounded well over 10 years (TDG: +595. 3%, AIR: +399. 6%), 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 Industrials sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both.

In terms of investment character: AIR is a small-cap high-growth stock; HEI is a mid-cap high-growth stock; TDG is a mid-cap income-oriented stock; KAI is a small-cap quality compounder stock. TDG pays a dividend while AIR, HEI, KAI do not, making them suitable for different income and tax situations. 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.