Should You Buy, Sell or Hold Biogen Stock After a 9% Rise in a Month?

After several difficult years marked by declining MS revenues, concerns about Alzheimer’s commercialization and pipeline skepticism, sentiment has improved due to stronger earnings, a more diversified growth portfolio, major M&A activity and growing confidence in late-stage pipeline assets. It seems investors are gaining confidence that the company’s multiyear turnaround is gaining traction.

Let’s understand Biogen’s strengths and weaknesses to better analyze how to play the stock in the post-earnings scenario.

Biogen’s MS Franchise Faces Continued Erosion

Biogen’s global MS revenues declined 13% in the second quarter, with Tecfidera and Tysabri down 53% and 0.8%, respectively. MS sales are declining due to generic competition for Tecfidera globally, biosimilar competition for Tysabri in Europe and rising competitive pressure in the MS market.

Multiple generic versions of Tecfidera are now available in North America, Brazil and the EU. A biosimilar referencing Tysabri was approved both in the United States and Europe in 2023 and is now launched in those countries.

Biogen expects revenues for MS products to continue declining in the second half due to accelerating generic competition for Tecfidera in the EU and biosimilar competition for Tysabri.

BIIB's Spinraza Benefits From New High-Dose Regimen

Spinraza sales declined around 5% in the first half, primarily due to lower demand. However, the recent approval of a higher-dose regimen in the United States, Japan and the EU, which reduces dosing frequency, should enhance the drug’s competitiveness in this highly competitive market. Biogen noted on its second-quarter conference call that the transition to the high-dose regimen has been significantly faster than expected. As a result, Spinraza sales increased 2% year over year in the second quarter, with stronger demand and stocking ahead of the high-dose regimen launch more than offsetting unfavorable shipment timing in certain international markets.

BIIB’s Growth Products Outperform Legacy MS Portfolio

Biogen has been undergoing a major transformation, and sales of its new growth products now exceed revenues from its legacy MS portfolio. Its growth drugs include Spinraza, Vumerity, new drugs Skyclarys (Friedreich’s ataxia), Qalsody (amyotrophic lateral sclerosis) and Zurzuvae (postpartum depression), as well as newly acquired drugs, Empaveli and Syfovre, from the Apellis acquisition, plus Alzheimer’s revenues from the Leqembi collaboration with Eisai.

Biogen’s growth products generated sales of $1.06 billion in the second quarter and rose 24% year over year and 25% on a sequential basis. Sales of the growth drugs surpassed the legacy multiple sclerosis portfolio, which generated $767 million in sales in the second quarter. Even excluding newly acquired Syfovre and Empaveli, revenues from the growth products were $933 million, up 9% year over year and 10% quarter over quarter. This was also higher than revenues from the legacy MS portfolio in the second quarter.

In the second quarter, Skyclarys revenues rose 29% to $168 million, Zurzuvae increased 53% to $71 million, while Alzheimer’s collaboration revenues from partner Eisai for Leqembi rose 16% to $63.7 million. Biogen has a collaboration with Supernus Pharmaceuticals SUPN for Zurzuvae.

A less frequent maintenance intravenous dosing version of Leqembi was approved by the FDA in January 2025. A subcutaneous autoinjector for maintenance dosing called Leqembi Iqlik was approved in August and launched in October 2025, while the Leqembi Iqlik subcutaneous autoinjector for at-home initiation dosing was approved by the FDA in July 2026. Regulatory filings for Leqembi Iqlik initiation are also underway in Japan and China. Biogen and Eisai believe that the introduction of blood-based diagnostics (which can help earlier detection of Alzheimer’s) and the launch of Leqembi Iqlik for maintenance and initiation should further drive Leqembi’s growth from 2027 onward.

Robust M&A Activity Strengthens BIIB’s R&D Pipeline

Biogen has strengthened its mid-to-late-stage neurology and immunology pipeline with regular M&A deals. Among some recent deals, Biogen acquired Apellis Pharmaceuticals in April, adding the commercialized medicines, Empaveli and Syfovre, for immune-mediated retinal disease and nephrology to its commercial portfolio. Biogen believes these two drugs will materially contribute to its top-line growth in the near and long term and expects the combined growth of Empaveli and Syfovre to be in the mid-to-high teens through at least 2028.

In July, it acquired San Diego-based privately held biotech RayThera, which added several anti-inflammatory candidates to its pipeline.

In May, Biogen acquired exclusive rights to felzartamab in China from TJ Biopharma. With this deal, Biogen now holds exclusive worldwide rights to felzartamab, which was acquired from the 2024 HI-Bio acquisition. Felzartamab is a key pipeline candidate for Biogen and is currently being evaluated in phase III studies for multiple immune-mediated diseases.

Five registrational phase III data readouts are expected over the next 12 months. Data from the pivotal study of litifilimab in systemic lupus erythematosus are expected by the end of this year, and data from litifilimab in cutaneous lupus erythematosus, felzartamab in antibody-mediated rejection and zorevunersen in Dravet syndrome are expected in 2027.

However, regular pipeline setbacks are a concern. Among recent setbacks, in May 2026, Biogen and partner Denali Therapeutics DNLI discontinued the development of BIIB122 in idiopathic Parkinson’s disease as a mid-stage study failed to meet its primary or secondary endpoints. The drug failed to slow the progression of Parkinson’s disease in patients.

BIIB’s Price, Valuation & Estimates

Biogen’s shares have risen 25.9% this year so far compared with an appreciation of 16.6% for the industry. The stock has also outperformed the sector and S&P 500 index, as seen in the chart below.

BIIB Stock Outperforms Industry, Sector & S&P 500

Image Source: Zacks Investment Research

From a valuation standpoint, Biogen is reasonably priced. Going by the price/earnings ratio, the company’s shares currently trade at 14.62 forward earnings, which is lower than 18.99 for the industry. However, the stock is trading above its five-year mean of 13.14.

BIIB Stock Valuation

Image Source: Zacks Investment Research

The Zacks Consensus Estimate for earnings has risen from $12.65 per share to $12.99 per share for 2026 over the past 30 days. For 2027, the consensus mark for earnings has declined from $16.50 to $16.28 per share over the same time frame.

BIIB’s Estimate Movement

Image Source: Zacks Investment Research

Stay Invested in BIIB Stock

After declining for several years, Biogen’s revenues have somewhat stabilized since 2024 due to contributions from newer products and pipeline progress. Some risks do remain. MS drug sales continue to decline because of generic competition. Leqembi’s long-term commercial trajectory is not fully proven, and several pipeline programs still face clinical and regulatory uncertainty.

However, lower sales of key multiple sclerosis drugs are being offset by higher revenues from growth drugs. Approvals of high-dose Spinraza and Leqembi Iqlik, the addition of newly acquired Syfovre and Empaveli brands and rapid growth in its late-stage pipeline position the company for sustainable growth as it decreases dependence on its mature MS business.

Biogen raised its 2026 revenue guidance to a mid-single-digit increase from 2025 compared with its previous expectation of a mid-single-digit decline on a constant-currency basis. The increase reflects higher expected revenues from its growth products, as well as the addition of Syfovre and Empaveli to its portfolio. Biogen also raised its adjusted EPS guidance to $15.85-$16.85 from $15.25-$16.25.

Biogen’s rising price, reasonable valuation, an improving pipeline and better sales prospects of new and acquired drugs are good enough reasons for those who own this Zacks Rank #3 (Hold) stock to stay invested for now. Youcan see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.

It remains to be seen if growth from Skyclarys, Leqembi, Spinraza, Zurzuvae and Apellis products can sustainably overcome the structural decline of the MS franchise.

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This article originally published on Zacks Investment Research (zacks.com).

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