GBIO vs ALNY

For growth investors, Generation Bio Co.

(GBIO) is the stronger pick with 236. 9% revenue growth year-over-year, versus 65. 2% for Alnylam Pharmaceuticals, Inc. (ALNY). Alnylam Pharmaceuticals, Inc. (ALNY) offers the better valuation at 127. 0x trailing P/E (44. 2x forward), making it the more compelling value choice. Analysts rate Alnylam Pharmaceuticals, Inc. (ALNY) a "Buy" — based on 52 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, Alnylam Pharmaceuticals, Inc.

(ALNY) delivered a total return of +125. 4%, compared to -98. 3% for Generation Bio Co. (GBIO). Over 10 years, the gap is even starker: ALNY returned +411. 9% versus GBIO's -97. 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), Alnylam Pharmaceuticals, Inc.

(ALNY) is the lower-risk stock at 0. 71β versus Generation Bio Co. 's 1. 68β — meaning GBIO is approximately 138% more volatile than ALNY relative to the S&P 500. On balance sheet safety, Generation Bio Co. (GBIO) carries a lower debt/equity ratio of 109% versus 162% for Alnylam Pharmaceuticals, Inc. — giving it more financial flexibility in a downturn.

By revenue growth (latest reported year), Generation Bio Co.

(GBIO) is pulling ahead at 236. 9% versus 65. 2% for Alnylam Pharmaceuticals, Inc. (ALNY). On earnings-per-share growth, the picture is similar: Alnylam Pharmaceuticals, Inc. grew EPS 206. 9% year-over-year, compared to -0. 7% for Generation Bio Co.. 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.

Alnylam Pharmaceuticals, Inc.

(ALNY) is the more profitable company, earning 8. 4% net margin versus -661. 9% for Generation Bio Co. — meaning it keeps 8. 4% of every revenue dollar as bottom-line profit. Operating margin tells a similar story: ALNY leads at 13. 5% versus -715. 8% for GBIO. At the gross margin level — before operating expenses — GBIO leads at 100. 0%, 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.

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, Alnylam Pharmaceuticals, Inc.

(ALNY) is the stronger choice — it scores higher on the combination of lower volatility, dividend reliability, and long-term compounding (low volatility (β 0. 71), +411. 9% 10Y return). Generation Bio Co. (GBIO) carries a higher beta of 1. 68 — meaning larger drawdowns in market downturns, which matters significantly when you cannot wait years for a recovery. Both have compounded well over 10 years (ALNY: +411. 9%, GBIO: -97. 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.