Alnylam Pharmaceuticals (ALNY) is under closer scrutiny after cutting its full-year 2026 TTR product sales guidance by about $200 million, which it linked to normalized growth, and is also facing a securities law investigation.

The share price of Alnylam Pharmaceuticals has been under pressure in recent months, with a 30 day share price return of down 19.25% and a year to date share price return of down 43.24%. At the same time, the 3 year total shareholder return of 23.51% and 5 year total shareholder return of 15.30% highlight a mixed longer term picture as the market reassesses growth expectations and risk after the guidance cut and subsequent legal scrutiny.

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Bulls view Alnylam Pharmaceuticals as a high growth RNAi platform facing temporary pressure. Bears see a reset story with risk of further disappointment. As you consider the recent guidance cut and investigation, which side does the current valuation appear to support?

Most Popular Narrative: 47.8% Undervalued

Against Alnylam Pharmaceuticals' last close of $227.12, the most followed narrative points to a fair value of $434.72. This creates a wide valuation gap that rests on ambitious growth and profitability assumptions.

The rapid and robust uptake of AMVUTTRA for ATTR-CM in its first full quarter post-approval, combined with near-universal first-line payer access and minimal patient out-of-pocket costs, indicates a much larger addressable market for Alnylam's RNAi therapies as diagnostics and disease awareness improve, supporting sustained double-digit revenue growth.

Want to see what underpins that bold fair value for Alnylam Pharmaceuticals? The narrative leans heavily on brisk revenue expansion, rising margins and a richer earnings multiple. Curious which specific growth path and profitability mix need to fall into place for that number to add up?

The narrative uses a 7.33% discount rate to bring projected cash flows and earnings out to 2029 back to today. The fair value of $434.72 therefore reflects both the time value of money and the risk profile described. Analysts feeding into this view expect strong earnings expansion, rising returns on equity and continued revenue growth that is ahead of broader US market expectations, which helps justify a higher implied future P/E multiple than the wider biotech sector.

At the same time, the narrative highlights that this fair value is sensitive to assumptions about the TTR franchise, especially AMVUTTRA, and how effectively Alnylam Pharmaceuticals can convert its large late stage and mid stage pipeline into durable earnings while managing pricing, reimbursement and cost pressures. For readers assessing the recent guidance cut and legal investigation, the key consideration is whether these longer term assumptions around revenue scale and margin improvement still feel realistic enough to close the current gap between price and fair value.

Result: Fair Value of $434.72 (UNDERVALUED)

However, the optimistic Alnylam Pharmaceuticals narrative could stumble if AMVUTTRA pricing pressures deepen, or if heavy TTR reliance meets tougher competition and reimbursement pushback.

Another View on Alnylam Pharmaceuticals Valuation

The fair value of $434.72 rests on ambitious earnings growth and margin expansion for Alnylam Pharmaceuticals. Yet the current P/E of 39.2x already sits well above the US Biotechs industry at 16.3x and the peer average at 32.7x, and even above a fair ratio of 32.6x. If sentiment cools further and the market moves closer to that fair ratio, today’s discount to fair value could narrow for reasons that are less friendly to existing holders.

Next Steps

With sentiment clearly split on Alnylam Pharmaceuticals, it helps to look past headlines and pressure to assess the full picture yourself. To see what investors currently view as the key positives, review the 3 key rewards

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This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.