IMOS vs AMKR vs ASX vs ONTO

For growth investors, ASE Technology Holding Co.

, Ltd. (ASX) is the stronger pick with 6. 8% revenue growth year-over-year, versus 1. 8% for Onto Innovation Inc. (ONTO). Amkor Technology, Inc. (AMKR) offers the better valuation at 48. 2x trailing P/E (36. 1x forward), making it the more compelling value choice. Analysts rate ASE Technology Holding Co. , Ltd. (ASX) a "Buy" — based on 5 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, Amkor Technology, Inc.

(AMKR) is the cheapest at 48. 2x versus Onto Innovation Inc. at 98. 6x. On forward P/E, ChipMOS TECHNOLOGIES Inc. is actually cheaper at 0. 8x — 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: ChipMOS TECHNOLOGIES Inc. wins at 0. 01x versus Amkor Technology, Inc. 's 25. 97x — a PEG below 1. 0 traditionally signals the market is underpricing earnings growth.

Over the past 5 years, ASE Technology Holding Co.

, Ltd. (ASX) delivered a total return of +331. 5%, compared to +98. 5% for ChipMOS TECHNOLOGIES Inc. (IMOS). Over 10 years, the gap is even starker: ONTO returned +1491% versus IMOS's +305. 9%. 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), ChipMOS TECHNOLOGIES Inc.

(IMOS) is the lower-risk stock at 1. 35β versus Amkor Technology, Inc. 's 2. 90β — meaning AMKR is approximately 116% more volatile than IMOS relative to the S&P 500. On balance sheet safety, Onto Innovation Inc. (ONTO) carries a lower debt/equity ratio of 1% versus 71% for ASE Technology Holding Co. , Ltd. — giving it more financial flexibility in a downturn.

By revenue growth (latest reported year), ASE Technology Holding Co.

, Ltd. (ASX) is pulling ahead at 6. 8% versus 1. 8% for Onto Innovation Inc. (ONTO). On earnings-per-share growth, the picture is similar: ASE Technology Holding Co. , Ltd. grew EPS 27. 7% year-over-year, compared to -31. 5% for Onto Innovation Inc.. Over a 3-year CAGR, ONTO leads at 0. 0% 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.

Onto Innovation Inc.

(ONTO) is the more profitable company, earning 13. 6% net margin versus 5. 6% for Amkor Technology, Inc. — meaning it keeps 13. 6% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: ONTO leads at 13. 2% versus 5. 6% for IMOS. At the gross margin level — before operating expenses — ONTO leads at 49. 7%, 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, ChipMOS TECHNOLOGIES Inc. (IMOS) is the more undervalued stock at a PEG of 0. 01x versus Amkor Technology, Inc. 's 25. 97x. A PEG below 1. 0 is traditionally considered the threshold for growth-adjusted undervaluation. On forward earnings alone, ChipMOS TECHNOLOGIES Inc. (IMOS) trades at 0. 8x forward P/E versus 39. 9x for Onto Innovation Inc. — 39. 1x cheaper on a one-year earnings basis. Analyst consensus price targets imply the most upside for ONTO: 21. 0% to $331. 67.

In this comparison, IMOS (1.

9% yield), ASX (1. 0% yield), AMKR (0. 5% yield) pay a dividend. ONTO does not pay a meaningful dividend and should not be held primarily for income.

For long-horizon retirement investors, ASE Technology Holding Co.

, Ltd. (ASX) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (1. 0% yield, +703. 9% 10Y return). Amkor Technology, Inc. (AMKR) carries a higher beta of 2. 90 — meaning larger drawdowns in market downturns, which matters significantly when you cannot wait years for a recovery. Both have compounded well over 10 years (ASX: +703. 9%, AMKR: +1299%), 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 Technology sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both.

IMOS, ASX pay a dividend while AMKR, ONTO 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.