ALNY vs ARWR: Which Is the Better Buy in 2026?

Same yardstick, side by side (as of August 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.

The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. ALNY and ARWR share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.

This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined ALNY and ARWR exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.

Alnylam Pharmaceuticals is the company that turned RNA interference, a Nobel-winning biological mechanism for silencing disease-causing genes, into an approved class of medicines. Its commercial portfolio includes Amvuttra (vutrisiran) and Onpattro for transthyretin (TTR) amyloidosis, Givlaari for acute hepatic porphyria, and Oxlumo for a rare kidney disorder, plus royalties on Leqvio, an cholesterol-lowering RNAi drug marketed by partner Novartis. The defining event was the March 2025 FDA approval of Amvuttra for ATTR amyloidosis with cardiomyopathy (ATTR-CM), a far larger patient population than its earlier polyneuropathy indication, based on the HELIOS-B trial showing a 28% reduction in death and cardiac events.

Full ALNY guide

Arrowhead Pharmaceuticals is a biopharmaceutical company built around RNA interference (RNAi), using its TRiM (Targeted RNAi Molecule) platform to design small interfering RNA (siRNA) medicines that silence disease-causing genes in the liver and, increasingly, in tissues like the lung and muscle. Its lead drug, plozasiran (marketed as REDEMPLO), targets APOC3 to lower triglycerides and was approved by the U.S. FDA in November 2025 for familial chylomicronemia syndrome (FCS), with additional approvals in China, Canada, Australia, and the European Union. Behind it sits a broad pipeline spanning cardiometabolic disease, obesity, pulmonary, CNS, and muscle targets, several of which are partnered.

Full ARWR guide

Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.

• ALNY drivers: Amvuttra ATTR-CM ramp; Crossing into sustained profitability.
• ARWR drivers: REDEMPLO (plozasiran) launch and label expansion; Partnership economics.

A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: Revenue is heavily concentrated in the TTR franchise, so any competitive share loss or reimbursement setback for Amvuttra would hit the whole story. For ARWR, arrowhead remains fundamentally a pipeline and partnership story, so revenue is lumpy and heavily dependent on milestone payments that do not recur each quarter, and the company posts operating losses in periods without such payments.

Growth-minded investors who believe the theme has years to run tend to accept the richer multiple for more upside; value-minded investors lean toward the cheaper forward earnings and steadier profile. Pick ALNY if you believe its drivers more; ARWR if you believe its. Many investors hold both, but since they share themes, that is a concentrated bet, not diversification. Decide deliberately and check overlap. For the full detail, see the ALNY and ARWR guides.

ALNY. Alnylam reached profitability in 2025 after nearly $3 billion in net product revenue, and Q1 2026 delivered about $1.0 billion in net product revenue with roughly $206 million of net income. At a market cap near $42 billion against 2026 revenue guidance of roughly $5 billion, the stock carries a premium multiple that prices in continued rapid growth. It pays no dividend and reinvests cash into its RNAi pipeline.

ARWR. Arrowhead's reported revenue is dominated by partnership and milestone payments, which makes results swing dramatically between quarters (a large Q1 FY2026 milestone quarter versus a much smaller Q2). Traditional valuation multiples are of limited use for a company at this stage, so investors tend to focus on the REDEMPLO launch trajectory, pipeline readouts, cash runway, and deal flow rather than trailing earnings.

Headline figures (approximate, JULY 2026): ALNY shows market cap ~$42B, net product revenue (fy2025) ~$3.0B, net product revenue (ttm) ~$3.5B, 2026 revenue guidance ~$4.9B to $5.3B; ARWR shows revenue (fy2025, ended sept 2025) ~$829M, q1 fy2026 revenue (oct-dec 2025) ~$264M, q2 fy2026 revenue (jan-mar 2026) ~$74M, total cash resources (early 2026) ~$1.78B.

ALNY and ARWR are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined ALNY and ARWR exposure against your real portfolio. It is not an investment adviser.