Biogen Inc. is an established biopharmaceutical company focused on developing treatments for neurodegenerative and rare diseases. Its declining multiple sclerosis franchise remains the company’s largest source of revenue, accounting for 40% of total revenue in 2025. Biogen also earns significant revenue from its CD20 collaboration agreements with Roche, which represented 19% of total revenue in 2025 and include the oncology drugs Rituxan and Gazyva, as well as the multiple sclerosis therapy Ocrevus. Newer growth franchises include Spinraza for spinal muscular atrophy with partner Ionis, Leqembi for Alzheimer’s disease through collaboration revenue from Eisai, Skyclarys for Friedreich’s ataxia from Reata, Zurzuvae for postpartum depression with Sage, and Qalsody for amyotrophic lateral sclerosis with Ionis.