Biogen Still Has Competitive Advantages in Neurology, but Its Moat Looks Narrow

We think Biogen's neurology, immunology, and focus on rare diseases support a narrow moat. Biogen's strategy has its roots in the 2003 merger of Biogen (Avonex for treating multiple sclerosis, or MS) and Idec (classic blood cancer drug Rituxan). The firm expanded its neurology portfolio beyond MS, including the blockbuster Spinraza for spinal muscular atrophy, or SMA, a rare neuromuscular disease. We see Biogen as a firm in transition, as MS revenue fades and new drugs for Alzheimer's, depression, and rare diseases begin to ramp up.