Biogen Inc. (NASDAQ: BIIB) reported its fourth-quarter and full-year 2025 financial results on February 6, 2026, signaling a definitive shift from a legacy company plagued by patent cliffs to a leaner, growth-oriented neurology powerhouse. Despite a 7% year-over-year revenue decline to $2.28 billion, the company beat Wall Street expectations and raised its outlook, driven by the surging adoption of its Alzheimer’s treatment, Leqembi, and its rare disease blockbuster, Skyclarys.
The earnings report highlights a pivotal "beat and raise" moment for the Cambridge-based biotech. Non-GAAP earnings per share (EPS) hit $1.99, far exceeding the analyst consensus of $1.61 to $1.72. While the company's legacy multiple sclerosis (MS) portfolio continues to erode under the weight of generic competition, the "New Biogen" growth products—which now account for a third of total revenue—grew by 19% annually, reaching $3.3 billion for the full year 2025.
Rebuilding the Foundation: A Year of Transformation
The journey to these Q4 results was defined by Biogen’s aggressive "Fit for Growth" restructuring program initiated by CEO Christopher Viehbacher. For much of 2024 and early 2025, Biogen struggled with the slow commercial launch of Leqembi, a therapy co-developed with Eisai Co., Ltd. (OTC: ESALY). Initial bottlenecks included a lack of PET scan infrastructure and slow Medicare reimbursement processes. However, throughout 2025, the company successfully cleared these hurdles, establishing a network of infusion centers that has finally allowed the drug to scale.
In the fourth quarter of 2025, global in-market sales for Leqembi reached $134 million, a 54% increase compared to the same period in 2024. This growth has allowed Biogen to maintain a dominant 60% share of the anti-amyloid market, even as formidable competition arrived from Eli Lilly and Company (NYSE: LLY). Meanwhile, Skyclarys, a treatment for Friedreich’s ataxia acquired through the Reata Pharmaceuticals buyout, has emerged as a major pillar of the business, generating $133 million in Q4 revenue.
The timeline leading to today’s announcement shows a company that has successfully traded volume for value. While total revenue for the full year 2025 landed at $9.9 billion—a modest 2% increase—the underlying profitability has improved as the company shed high-cost, low-margin legacy programs. Investors reacted positively to the news, sending Biogen shares up 4.26% to close at $185.36 on the day of the announcement.
Winners and Losers in the Neuro-Innovation Race
Biogen (NASDAQ: BIIB) stands as the clear winner of the current quarter, proving to skeptical investors that it can survive the "patent cliff" of its older MS drugs like Tecfidera. By diversifying into rare diseases and Alzheimer's, the company has stabilized its floor. Eisai (OTC: ESALY) also shares in this victory, as the success of Leqembi validates their long-term collaborative strategy and provides a steady stream of royalty and profit-sharing revenue.
On the other hand, traditional players in the multiple sclerosis market continue to feel the squeeze. As Biogen pivots away from MS, the segment is becoming increasingly commoditized, leaving little room for premium pricing. Companies like Novartis AG (NYSE: NVS) and Roche Holding AG (OTC: RHHBY), which have their own neurology portfolios, are watching closely as Biogen sets the standard for the next generation of "specialty" neurology drugs that require high-touch clinical infrastructure.
Eli Lilly and Company (NYSE: LLY) remains a complicated competitor. While Lilly’s Alzheimer’s drug, Kisunla (donanemab), saw Q4 sales jump to $109 million, it still trails Leqembi in total market share. However, Lilly's massive financial firepower from its GLP-1 "weight loss" franchise means it can afford to play a long game in neurology that Biogen cannot. For now, the market seems large enough for both, but the "loser" in this scenario may be any smaller biotech without a major partner to navigate the complex Medicare and diagnostic requirements of the Alzheimer’s space.
Shifting Tides in Healthcare and Policy
Biogen’s Q4 performance is a microcosm of a larger trend in the biopharmaceutical industry: the move toward "precision neurology." Much like oncology shifted toward targeted therapies a decade ago, neurology is now moving away from broad-spectrum symptom management toward disease-modifying therapies. The focus on biomarkers and PET imaging seen in the Leqembi launch is likely to become the standard for future treatments in Parkinson’s and ALS.
The regulatory environment also continues to evolve. The successful rollout of Leqembi was only possible after the Centers for Medicare & Medicaid Services (CMS) streamlined coverage for amyloid-targeting therapies. This precedent is now paving the way for other neuro-innovations. Furthermore, Biogen’s focus on its "Fit for Growth" program reflects a broader industry trend where large-cap biotechs are prioritizing "pipeline-in-a-product" strategies—focusing on a few high-value assets rather than a sprawling, inefficient R&D list.
Historical precedents, such as the launch of the first statins or biologics for rheumatoid arthritis, suggest that we are in the "early adopter" phase of a massive new market. Analysts note that while the current $500 million annual run rate for Leqembi is significant, it represents only a fraction of the estimated 6 million Americans living with early-stage Alzheimer’s, suggesting decades of potential growth if diagnostic rates continue to rise.
Looking Ahead: The Pipeline Card-Flip
The next 12 months will be a "catalyst-rich" period that will define Biogen’s trajectory for the rest of the decade. CEO Christopher Viehbacher has noted that 2026 is the year the company "turns over the cards" on several late-stage trials. The most immediate milestone is the April 3, 2026, PDUFA date for high-dose Spinraza, which Biogen hopes will defend its spinal muscular atrophy (SMA) franchise against newer gene therapies.
Perhaps even more critical is the May 24, 2026, decision date for the Leqembi subcutaneous autoinjector. If approved, this would allow patients to initiate treatment with a simple injection at home rather than a bi-weekly infusion at a clinic. This could drastically lower the barrier to entry for patients and accelerate market penetration. Additionally, data from the LUMA study for Parkinson’s disease, in collaboration with Denali Therapeutics (NASDAQ: DNLI), is expected as early as March 2026.
Strategic pivots may still be required. While the rare disease and Alzheimer’s units are thriving, Biogen remains vulnerable to any clinical setbacks in its immunology pipeline, particularly litifilimab for lupus. Should these trials disappoint, Biogen may need to return to the M&A market to bolster its 2027-2028 growth profile.
The Bottom Line for Investors
Biogen’s Q4 results offer a masterclass in corporate reinvention. By successfully transitioning its revenue base from aging MS drugs to a modern portfolio of neuro-innovations, the company has silenced critics who feared a permanent decline. The 15.1% rise in Biogen’s stock over the past year reflects a growing confidence that the "New Biogen" is not just a concept, but a profitable reality.
Moving forward, investors should keep a close watch on the subcutaneous approval of Leqembi and the upcoming Parkinson’s data. These events will determine whether Biogen can maintain its lead over Eli Lilly or if it will be forced to share the crown. With the stock currently trading at a relatively modest 12x forward earnings compared to the broader biotech sector, many analysts view it as a value play in a high-growth field.
The takeaway is clear: the era of "wait and see" for Biogen is over. The company has built the infrastructure, secured the market share, and is now entering a phase of execution. For the healthcare market at large, Biogen’s success serves as a blueprint for how legacy pharmaceutical giants can navigate the transition into the next generation of medicine.
This content is intended for informational purposes only and is not financial advice.
