QSI vs ILMN

For growth investors, Illumina, Inc.

(ILMN) is the stronger pick with -0. 8% revenue growth year-over-year, versus -20. 3% for Quantum-Si incorporated (QSI). Illumina, Inc. (ILMN) offers the better valuation at 26. 0x trailing P/E (27. 2x forward), making it the more compelling value choice. Analysts rate Quantum-Si incorporated (QSI) a "Buy" — based on 2 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.

Over the past 5 years, Illumina, Inc.

(ILMN) delivered a total return of -61. 6%, compared to -91. 2% for Quantum-Si incorporated (QSI). Over 10 years, the gap is even starker: ILMN returned +3. 0% versus QSI's -90. 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), Illumina, Inc.

(ILMN) is the lower-risk stock at 1. 20β versus Quantum-Si incorporated's 3. 69β — meaning QSI is approximately 206% more volatile than ILMN relative to the S&P 500. On balance sheet safety, Quantum-Si incorporated (QSI) carries a lower debt/equity ratio of 2% versus 94% for Illumina, Inc. — giving it more financial flexibility in a downturn.

By revenue growth (latest reported year), Illumina, Inc.

(ILMN) is pulling ahead at -0. 8% versus -20. 3% for Quantum-Si incorporated (QSI). On earnings-per-share growth, the picture is similar: Illumina, Inc. grew EPS 170. 9% year-over-year, compared to 28. 2% for Quantum-Si incorporated. 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.

Illumina, Inc.

(ILMN) is the more profitable company, earning 19. 6% net margin versus -41. 6% for Quantum-Si incorporated — meaning it keeps 19. 6% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: ILMN leads at 19. 9% versus -39. 8% for QSI. At the gross margin level — before operating expenses — ILMN leads at 66. 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.

Analyst consensus price targets imply the most upside for QSI: 10.

3% to $1. 00.

None of the stocks in this comparison currently pay a material dividend.

All are effectively zero-yield and should be held for capital appreciation rather than income.

For long-horizon retirement investors, Illumina, Inc.

(ILMN) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (low volatility (β 1. 20)). Quantum-Si incorporated (QSI) carries a higher beta of 3. 69 — meaning larger drawdowns in market downturns, which matters significantly when you cannot wait years for a recovery. Both have compounded well over 10 years (ILMN: +3. 0%, QSI: -90. 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 Healthcare sector, making this a peer-level intra-sector comparison — the same macro tailwinds and headwinds will affect both.

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.