Should You Buy, Sell or Hold BIIB Stock After it Rises Almost 12% YTD?
📈 Biogen (BIIB) stock has risen 11.5% year-to-date in 2026, driven by robust first-quarter earnings that beat analyst estimates for both profit and sales.
💰 Earnings per share increased by 18%, while revenues declined 2% on a constant currency basis due to lower sales of legacy drugs Tecfidera and Spinraza.
🔄 Investor sentiment has improved as newer products like Skyclarys, Qalsody, and Zurzuvae begin to offset declines in the multiple sclerosis franchise.
⚠️ Global MS revenues declined 3% in the first quarter due to generic competition for Tecfidera and biosimilar pressure on Tysabri in Europe and the US.
🏛️ The European Patent Office revoked a key Tecfidera patent in November 2025, accelerating generic launches throughout Europe and impacting Biogen's revenue outlook.
💉 Spinraza sales dropped around 12% in the first quarter, though a higher-dose regimen approved in the US, Japan, and EU aims to improve competitiveness.
🧠 Leqembi commands over 60% of the anti-amyloid therapy market share in the US and has seen growth accelerate after a slow launch in 2023.
💉 A subcutaneous autoinjector version of Leqembi (Leqembi Iqlik) was launched in October 2025, with FDA priority review expected for initiation dosing approval by August.
📦 Biogen's new drugs generated $851 million in first-quarter sales, a 12% year-over-year increase, though they are not yet sufficient to fully offset MS franchise declines.
🤝 In April 2026, Biogen acquired Apellis Pharmaceuticals, adding commercialized medicines for immune-mediated retinal disease and nephrology to its portfolio.
📈 The Apellis acquisition is expected to be accretive to earnings in 2027 and boost adjusted EPS growth over the remainder of the decade.
🔬 Biogen holds exclusive worldwide rights to felzartamab for multiple immune-mediated diseases following a May deal with TJ Biopharma in China.
⚠️ Pipeline setbacks include the discontinuation of BIIB122 for idiopathic Parkinson's disease in May 2026 after a mid-stage study failed to meet endpoints.
📉 Biogen shares have risen 51.3% over the past year, significantly outperforming the industry average of 25.8% and the S&P 500 index.
💵 The stock trades at a forward price-to-earnings ratio of 12.93, which is lower than the industry average of 17.42 and below its five-year mean.
📉 Analyst consensus earnings estimates for 2026 have declined from $15.83 to $14.25 per share over the past 60 days due to M&A-related costs.
📈 Consensus earnings estimates for 2027 have increased slightly from $16.39 to $16.56 per share over the same period.
🛡️ Biogen's Zacks Rank is currently #3 (Hold), with analysts suggesting investors stay invested given the reasonable valuation and improving pipeline.
🚀 The Apellis deal could prove transformative by immediately adding commercial products and strengthening Biogen's position in immunology and nephrology.
📊 Data readouts are expected over the next 18 months for litifilimab, felzartamab, and zorevunersen across various phase III studies.
⚠️ Risks remain regarding the long-term commercial trajectory of Leqembi and clinical/regulatory uncertainty for several pipeline programs.
- Biogen stock has risen 11.5% in 2026 so far, driven by robust first-quarter results that beat estimates for both earnings and sales.
- Earnings rose 18% year-over-year, demonstrating strong operational performance despite a 2% revenue decline on a constant currency basis.
- Investor confidence is improving as newer products like Skyclarys, Qalsody, and Zurzuvae successfully offset declines in legacy MS franchise revenues.
- Biogen's growth portfolio generated $851 million in sales for the first quarter, representing a 12% year-over-year increase.
- The acquisition of Apellis Pharmaceuticals in April 2026 adds commercialized medicines Empaveli and Syfovre to the portfolio and is expected to be accretive to earnings in 2027.
- Biogen now holds exclusive worldwide rights to felzartamab for multiple immune-mediated diseases following its acquisition from TJ Biopharma in May.
- The stock trades at a forward P/E ratio of 12.93, which is lower than the industry average of 17.42 and below its five-year mean of 13.27.
- Consensus earnings estimates for 2027 have increased from $16.39 to $16.56 per share over the past 60 days, signaling positive analyst sentiment.
- Leqembi commands over 60% of the anti-amyloid therapy market share in the United States and has been launched in Japan, China, and the EU.
- A subcutaneous autoinjector for Leqembi maintenance dosing was launched in October 2025, with a priority review decision expected in August for initiation dosing.
- Multiple generic versions of Tecfidera have launched in North America, Brazil, and Europe following the revocation of a key patent by the European Patent Office in November 2025, accelerating competitive pressure.
- A Tysabri biosimilar is now available in some European countries with entry into the United States expected soon, further eroding sales of Biogen's MS portfolio.
- Spinraza sales declined around 12% in the first quarter due to lower demand, adding to the top-line pressure from the declining MS franchise.
- Despite growth in new products like Leqembi, Skyclarys, Qalsody, and Zurzuvae, these are currently insufficient to fully offset the near-term top-line decline of the MS franchise.
- Biogen discontinued development of BIIB122 for idiopathic Parkinson's disease in May 2026 after a mid-stage study failed to meet its primary or secondary endpoints, representing a pipeline setback.
- The Zacks Consensus Estimate for earnings has declined from $15.83 per share to $14.25 per share for 2026 over the past 60 days, reflecting analyst concerns about near-term performance.
- Leqembi's long-term commercial trajectory is not fully proven, and several pipeline programs still face clinical and regulatory uncertainty.
