Biogen Inc.
Acquisitions
8
Major Deals Covered
$18.2B
Disclosed Deal Value
Biogen's largest disclosed acquisition here is Reata Pharmaceuticals for $7.3B in 2023. This page covers 8 major deals from 2003 to 2026, each with its price where disclosed and the reason behind it.
| Company | Year | Price | Purpose |
|---|---|---|---|
| IDEC Pharmaceuticals | 2003 | Undisclosed | An all-stock merger valued at about $6.8 billion that combined Biogen's MS business with IDEC's oncology and immunology products, including Rituxan, marketed with Genentech. |
| Fumapharm AG | 2006 | Undisclosed | Bought the Swiss maker of the psoriasis drug Fumaderm and the oral fumarate BG-12, then being studied in multiple sclerosis. |
| Elan (Tysabri rights) | 2013 | $3.3B | Paid Elan $3.25 billion for full ownership of Tysabri, which the two companies had shared. |
| Nightstar Therapeutics | 2019 | $800.0M | Acquired the UK gene therapy company for $25.50 per share to build a pipeline for inherited retinal disorders. |
| Reata Pharmaceuticals | 2023 | $7.3B | Bought Reata for $172.50 per share in cash to obtain Skyclarys, the first approved treatment for Friedreich's ataxia. |
| Human Immunology Biosciences (HI-Bio) | 2024 | $1.1B | Paid $1.15 billion upfront, with up to $650 million in milestones, for felzartamab, an anti-CD38 antibody for immune-mediated kidney and transplant diseases. |
| Alcyone Therapeutics | 2025 | $85.0M | Acquired a developer of implantable devices for delivering antisense drugs into the spinal fluid. |
| Apellis Pharmaceuticals | 2026 | $5.6B | Paid $41 per share in cash plus a contingent value right of up to $4 per share for Apellis, maker of Syfovre and Empaveli, completed May 14, 2026. |
2026
$5.6B
Paid $41 per share in cash plus a contingent value right of up to $4 per share for Apellis, maker of Syfovre and Empaveli, completed May 14, 2026.
Added $689 million of 2025 product sales, a US nephrology and ophthalmology sales force, and at least $250 million of expected cost savings by the end of 2027.
2025
$85M
Acquired a developer of implantable devices for delivering antisense drugs into the spinal fluid.
Intended to make repeat intrathecal dosing of drugs such as Spinraza and salanersen easier for patients.
2024
$1.1B
Paid $1.15 billion upfront, with up to $650 million in milestones, for felzartamab, an anti-CD38 antibody for immune-mediated kidney and transplant diseases.
Felzartamab is in Phase 3 for three kidney diseases, with the first readout expected in the first half of 2027.
2023
$7.3B
Bought Reata for $172.50 per share in cash to obtain Skyclarys, the first approved treatment for Friedreich's ataxia.
Biogen's largest cash acquisition; Skyclarys reached $168 million of revenue in Q2 2026, up 29%.
2019
$800M
Acquired the UK gene therapy company for $25.50 per share to build a pipeline for inherited retinal disorders.
The lead programs did not reach the market, and Biogen later scaled back gene therapy.
2013
$3.3B
Paid Elan $3.25 billion for full ownership of Tysabri, which the two companies had shared.
Gave Biogen all Tysabri economics; the drug still produced $451 million in Q2 2026.
2006
Bought the Swiss maker of the psoriasis drug Fumaderm and the oral fumarate BG-12, then being studied in multiple sclerosis.
BG-12 became Tecfidera, approved in 2013 and Biogen's best-selling drug by the late 2010s.
2003
An all-stock merger valued at about $6.8 billion that combined Biogen's MS business with IDEC's oncology and immunology products, including Rituxan, marketed with Genentech.
Created Biogen Idec, then the third-largest biotechnology company, and the origin of today's anti-CD20 royalty stream.
Viehbacher's plan has three parts. First, cut costs: the Fit for Growth program launched in 2023 targeted about $1 billion of gross savings and removed roughly 1,000 roles. Second, launch newer drugs such as Leqembi, Skyclarys, Zurzuvae and Qalsody; the growth portfolio reached $1.1 billion of revenue in Q2 2026, up 24%. Third, buy late-stage or commercial assets beyond core neurology: Reata ($7.3 billion, 2023), HI-Bio ($1.15 billion upfront, 2024) and Apellis (about $5.6 billion, 2026), which together move Biogen into rare disease, immunology, nephrology and ophthalmology.
Biogen discovers, licenses or acquires drug candidates, runs the clinical trials needed for approval, manufactures most of its biologics in Research Triangle Park, North Carolina and Solothurn, Switzerland, and sells approved products through specialty pharmacies, hospitals and infusion centers. Revenue comes from three places: product sales (about 70% of Q2 2026 revenue, led by Tysabri, Spinraza, Vumerity, Skyclarys, Syfovre and Zurzuvae), royalties and profit share on Genentech's anti-CD20 drugs such as Ocrevus ($514 million in Q2 2026), and its share of Leqembi economics with Eisai plus contract manufacturing. Prices are high because the diseases are severe and patient groups small: Spinraza launched at about $750,000 for the first year of treatment. Many assets are partnered, so Biogen shares costs and profits with Eisai, Ionis, UCB, Supernus and others.
Reata Pharmaceuticals, bought in September 2023 for $7.3 billion ($172.50 per share in cash), is Biogen's largest cash acquisition. It added Skyclarys for Friedreich's ataxia.
Biogen paid $41 per share in cash, about $5.6 billion, plus a contingent value right worth up to $4 per share tied to Syfovre sales. The deal was announced on March 31, 2026 and completed on May 14, 2026.
Biogen acquired Human Immunology Biosciences in July 2024 for $1.15 billion upfront plus up to $650 million in milestones, gaining felzartamab, now in Phase 3 for three kidney diseases.
In 2003 Biogen merged with IDEC Pharmaceuticals in an all-stock deal valued at about $6.8 billion, creating Biogen Idec and bringing the Rituxan partnership with Genentech.
Yes. It spun off its hemophilia business as Bioverativ in February 2017, which Sanofi bought in 2018 for $11.6 billion, and in 2022 it sold its stake in the biosimilars joint venture Samsung Bioepis to Samsung Biologics.
Biogen completed the $85 million purchase of Alcyone Therapeutics, a developer of implantable spinal drug-delivery devices, in November 2025, and in March 2026 paid Alteogen $20 million upfront to use its enzyme technology to turn two IV biologics into injections.
In 2023, Biogen executed a massive $7.3 billion acquisition of Reata Pharmaceuticals to immediately acquire its newly approved drug for Friedreich's ataxia, significantly bolstering its rare disease pipeline.
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