ARWR vs SLN: 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. ARWR and SLN 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 ARWR and SLN 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.

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

Silence Therapeutics plc is a London-headquartered biotechnology company built around short interfering RNA, a class of drug that switches off the production of a specific disease-causing protein in the liver rather than blocking it after the fact. Its proprietary discovery platform, marketed as mRNAi GOLD, attaches a GalNAc sugar to the siRNA so the molecule is taken up by liver cells, which is the same delivery approach behind the approved RNAi drugs on the market today. Two candidates carry the story. Zerlasiran silences the LPA gene to lower lipoprotein(a), an inherited cardiovascular risk factor with no approved therapy, and produced reductions of more than 80 percent in its Phase 2 ALPACAR-360 trial. Divesiran targets TMPRSS6 to raise hepcidin and control red blood cell production in polycythemia vera, a chronic blood cancer whose patients are otherwise managed with repeated therapeutic phlebotomy. A third asset, SLN312, was returned to Silence in March 2026 after AstraZeneca elected not to advance it past Phase 1.

Full SLN guide

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

• ARWR drivers: REDEMPLO (plozasiran) launch and label expansion; Partnership economics.
• SLN drivers: Divesiran and the SANRECO Phase 2 readout; A partner for zerlasiran.

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: 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. For SLN, silence generates essentially no product revenue, so the equity is a claim on clinical outcomes and financing terms rather than on earnings.

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 ARWR if you believe its drivers more; SLN 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 ARWR and SLN guides.

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.

SLN. Conventional valuation multiples do not apply here: with trailing revenue under $1 million, a price-to-sales or price-to-earnings figure would be arithmetic noise. What the roughly $565 million market cap actually represents is about $72 million of cash plus a market-assigned value of roughly half a billion dollars for divesiran, zerlasiran and the platform behind them. Enterprise value therefore sits near $490 million, which is the number worth comparing against the probability-weighted commercial case for a polycythemia vera drug and a partnered lipoprotein(a) drug.

Headline figures (approximate, JULY 2026): 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; SLN shows market cap ~$565M, revenue (ttm) ~$0.6M (collaboration revenue only, down from ~$42M in FY2024), net loss (ttm) ~$60M, cash and short-term investments (june 30, 2026) ~$72M.

ARWR and SLN 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 ARWR and SLN exposure against your real portfolio. It is not an investment adviser.