Biogen Inc. (BIIB) Stock Price & How to Invest
Last updated July 2026
Short answer
Biogen (BIIB) is a large-cap neuroscience biotech in transition: legacy multiple sclerosis and Spinraza revenue are eroding while it bets on the Alzheimer's drug Leqembi, rare-disease franchises, and the roughly $5.6 billion Apellis acquisition to restart growth. You would own it as a turnaround story trading at a below-market biotech multiple, not as a steady grower.
BIIB stock price
As of 2026-08-17, Biogen Inc. (BIIB) last closed at $209.40, up 54.1% over the past year. Over the past 52 weeks it has traded between $132.22 and $216.63.
Prices are daily closing prices from Yahoo Finance and may be delayed. For the live quote, check your broker or Biogen Inc.'s investor relations page. Walnut is informational, not investment advice.
What does Biogen Inc. (BIIB) do?
Biogen is a Cambridge, Massachusetts biotechnology company built on neuroscience. Its historic core is multiple sclerosis (Tysabri, Tecfidera, Vumerity), and it co-developed the spinal muscular atrophy drug Spinraza with Ionis. Its growth story now centers on Leqembi, the Alzheimer's antibody it markets with partner Eisai, alongside newer rare-disease products Skyclarys (Friedreich's ataxia) and Qalsody (ALS). In 2026 it closed the roughly $5.6 billion acquisition of Apellis Pharmaceuticals, adding the retinal drug Syfovre for geographic atrophy and Empaveli for rare blood and kidney diseases.
The investment picture is a classic biotech transition. Legacy MS sales face generic and biosimilar erosion (Biogen guides MS revenue excluding Vumerity down a mid-teen percentage in 2026) and total revenue is expected to fall a mid-single-digit percentage for the full year. Against that, Leqembi is scaling fast (Q1 2026 in-market sales up 74 percent year over year), and management is using acquisitions and cost discipline to defend earnings. The stock trades at a low double-digit forward earnings multiple, reflecting both the cheap valuation and the uncertainty over whether new launches can outrun the declining base.
What's driving Biogen Inc. (BIIB)?
1. Leqembi Alzheimer's ramp
Leqembi is the single biggest swing factor, with Q1 2026 worldwide in-market sales around $168 million, up roughly 74 percent year over year across the US, Japan, and China. Real-world data showing about 78 percent of patients still on therapy at 18 months supports the durability of the franchise. Subcutaneous maintenance dosing (IQLIK) could broaden adoption if uptake and reimbursement continue to build.
2. Rare-disease and new-product portfolio
Skyclarys (Friedreich's ataxia) grew roughly 22 percent year over year to about $151 million in Q1 2026, and high-dose Spinraza was approved to defend the SMA franchise against competition. The Apellis deal adds Syfovre for geographic atrophy and Empaveli for PNH and rare kidney diseases, products that together generated roughly $689 million in 2025. These launches are the intended replacements for shrinking legacy sales.
3. Cost discipline and cash-funded M&A
Biogen has leaned on operating-expense reductions to protect earnings, delivering non-GAAP EPS of about $3.57 in Q1 2026, up double digits year over year despite roughly flat revenue. It funded most of the Apellis purchase with cash on hand plus modest bank debt, preserving flexibility. The strategy is to convert a mature cash-generating base into growth through selective dealmaking.
What are the risks to Biogen Inc. (BIIB)?
The legacy MS business (Tecfidera, Tysabri) continues to decline against generics and biosimilars, and full-year 2026 total revenue is guided down a mid-single-digit percentage. Leqembi faces direct competition from Eli Lilly's Kisunla and lingering questions about diagnostic access, infusion logistics, and payer coverage, so its ramp could disappoint. Large acquisitions like Apellis add integration and execution risk, and contingent value payments tied to Syfovre sales create uncertain future costs. Biotech pipelines carry binary clinical and regulatory outcomes, and a single trial failure or safety signal can move the stock sharply. The low valuation reflects genuine skepticism that new products can offset the eroding base fast enough.
What is the Biogen Inc. (BIIB) forecast?
31 analysts publish price targets on BIIB, averaging $234.35 against a $202.95 price as of August 2026, or +15.5%. The published targets run from $157.00 to $300.00, a moderate spread, and the ratings split 23 buy, 12 hold, 1 sell. Over the last six months there have been 9 raises and 3 cuts among the published actions. A price target is what an analyst published on a date, not a prediction, and sell-side ratings skew positive across the whole market.
Read the full BIIB forecast and price target for the target table, the recent rating actions by firm, and how the consensus has shifted.
Is BIIB a buy or a sell?
We give no verdict on Biogen Inc.. Both cases are real, which is why the question is contested at all, so here is the strongest version of each.
The case for buying. Leqembi Alzheimer's ramp. Leqembi is the single biggest swing factor, with Q1 2026 worldwide in-market sales around $168 million, up roughly 74 percent year over year across the US, Japan, and China. The most optimistic published target, $300.00, assumes this works close to its best case.
The case against. The legacy MS business (Tecfidera, Tysabri) continues to decline against generics and biosimilars, and full-year 2026 total revenue is guided down a mid-single-digit percentage. The most pessimistic target, $157.00, is roughly what BIIB is worth if this bites instead.
Read the full bull and bear case on BIIB, including what would have to change to break either one. Walnut is not an investment adviser.
How is Biogen Inc. (BIIB) valued? (approximate, MAY 2026)
A simple financial snapshot. These are approximations and refresh quarterly; for current figures see Biogen Inc.'s investor relations page or your broker.
- Revenue (TTM): ~$9.7B
- Q1 2026 revenue: ~$2.5B (up ~2% YoY)
- Q1 2026 non-GAAP EPS: ~$3.57
- Market cap: ~$29B
- Forward P/E: ~12x
- Recent share price: ~$183
Biogen trades at a low double-digit forward earnings multiple, well below the drug-manufacturer industry median, reflecting a shrinking legacy base and turnaround uncertainty. Q1 2026 earnings beat expectations on cost discipline and Leqembi momentum, but management still guides full-year revenue down a mid-single-digit percentage. The valuation prices in doubt that new launches will outrun legacy erosion.
Which ETFs hold Biogen Inc. (BIIB)?
If you want BIIB exposure as part of a larger bundle rather than directly, these ETFs hold it meaningfully. Weights are approximate and refresh quarterly.
What themes does Biogen Inc. (BIIB) fit?
These are the investment theses BIIB naturally fits into. Each links to a full theme guide listing every other stock that belongs and the ETFs commonly used as a passive proxy.
Who competes with Biogen Inc. (BIIB)?
Alzheimer's and neurology
Eli Lilly (Kisunla/donanemab) is the most direct rival to Leqembi in Alzheimer's, while Eisai is both Biogen's Leqembi partner and a neuroscience peer. Roche and other large pharma compete across the broader neurology space.
Multiple sclerosis and rare neuromuscular
Roche (Ocrevus), Novartis, Sanofi, and generic/biosimilar makers pressure Biogen's MS franchise. In spinal muscular atrophy, Roche (Evrysdi) and Novartis (Zolgensma) compete with Spinraza.
Rare disease and retinal (post-Apellis)
In geographic atrophy, Astellas (Izervay) competes directly with the newly acquired Syfovre. Other large biotechs such as Vertex, Regeneron, and Alexion (AstraZeneca) compete across rare immune and blood disorders.
What stocks are similar to Biogen Inc. (BIIB)?
Other names that sit close to BIIB: same theme, named as a direct competitor, or held beside it in the same funds. Each entry says which. Worth a look if you are thinking about diversification within a thesis rather than concentration on one ticker.
How to invest in Biogen Inc. (BIIB)
There are three common ways to get BIIB exposure. Buy shares (or fractional shares) directly at any major broker. Hold an ETF that includes it (BBH, FBT, IBB), which spreads the position across many companies. Or build it into a focused thematic portfolio, so BIIB sits alongside other stocks that express the same thesis.
Walnut takes the portfolio route. Describe a thesis where BIIB fits (for example “AI infrastructure” or “dividend-growth large-caps”) and the AI proposes 5 to 6 constituents with target weights. You review the plan and fund it through your own broker when you're ready.
New to this? Start with how to invest in stocks, see how to analyze a stock with AI, or compare the best AI stock analyzers.
The bottom line on Biogen Inc. (BIIB)
BIIB is a cheap, cash-generative biotech leaning on Leqembi and freshly acquired products to offset a shrinking legacy base, so the thesis lives or dies on the new pipeline.
More on Biogen Inc. (BIIB)
Whether BIIB is worth buying today depends more on your time horizon and what you already hold than on any single call. We walk through valuation, what would have to go right, and the risks in is BIIB a buy or a sell?, and where the stock could go from here in the BIIB stock forecast.
For income investors, whether BIIB pays a dividend and how the payout looks is covered in does BIIB pay a dividend? And to weigh BIIB against a peer, read the full side-by-side comparisons: BIIB vs VRTX and BIIB vs REGN.
Wondering how BIIB fits the portfolio you already own? Walnut is an AI investing app that connects your brokerage read-only and answers questions like that about your actual holdings: overlap, concentration, and how each position tracks the S&P 500. Compare the best AI portfolio analyzers or see the best AI investing apps in 2026.
Investing in Biogen Inc. with AI
Connect the broker you already use and ask Walnut's AI how BIIB fits what you actually hold: whether you own it already through a fund, what it would do to your concentration, and how it has tracked the S&P 500. Read-only by default, and you approve anything before it reaches your broker.
FAQ
What does Biogen do?
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Biogen is a biotechnology company focused on neuroscience and rare diseases. Its products span multiple sclerosis (Tysabri, Tecfidera), the Alzheimer's drug Leqembi (with Eisai), spinal muscular atrophy (Spinraza), Friedreich's ataxia (Skyclarys), and, after the 2026 Apellis acquisition, retinal and rare-blood conditions.
Is BIIB a good investment?
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That depends on your goals and risk tolerance, and Walnut is not an investment adviser. BIIB is a turnaround story: it trades cheaply relative to peers, but its legacy revenue is declining and the thesis rests on Leqembi and newer products succeeding. Consider how much biotech and single-drug risk fits your portfolio.
Why is Biogen's revenue declining?
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Its historic multiple sclerosis franchise faces generic competition for Tecfidera and biosimilar competition for Tysabri, and Spinraza faces newer SMA rivals. Biogen guides full-year 2026 total revenue down a mid-single-digit percentage, with MS products excluding Vumerity down a mid-teen percentage.
How important is Leqembi to Biogen?
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Leqembi is the company's most important growth driver. Worldwide in-market sales were around $168 million in Q1 2026, up roughly 74 percent year over year. Biogen shares the economics with partner Eisai, and a subcutaneous maintenance version could widen adoption if reimbursement and uptake continue building.
What was the Apellis acquisition?
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In 2026 Biogen acquired Apellis Pharmaceuticals for about $5.6 billion in cash plus a contingent value right tied to Syfovre sales. The deal added Syfovre (for geographic atrophy, a retinal disease) and Empaveli (for rare blood and kidney disorders), products that generated roughly $689 million in 2025.
How is BIIB valued?
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Biogen carried a market cap around $29 billion in mid-2026, with a recent share price near $183 and a forward P/E of roughly 12x. That is well below the drug-manufacturer industry median, reflecting skepticism about whether new products can offset declining legacy sales.
Who are Biogen's main competitors?
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In Alzheimer's, Eli Lilly (Kisunla) competes with Leqembi. In multiple sclerosis, Roche (Ocrevus), Novartis, and Sanofi apply pressure. In spinal muscular atrophy, Roche (Evrysdi) and Novartis (Zolgensma) compete with Spinraza, and Astellas (Izervay) rivals the acquired Syfovre in geographic atrophy.
Does Biogen pay a dividend?
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Biogen has historically not paid a regular dividend, instead directing capital toward research, share buybacks, and acquisitions such as the 2026 Apellis deal. Investors seeking income would typically look elsewhere; the case for BIIB is capital appreciation from a successful pipeline transition.
Guides that feature BIIB
BIIB is one of the names covered in these guides. Each one puts the stock next to its peers so you can see where it fits rather than judging it alone.
Walnut is informational, not investment advice. Financial figures on this page are approximations; always verify current numbers with Biogen Inc.'s investor relations page or your broker before making investment decisions.