Biogen Earnings: Guidance Slightly Disappointing, Fair Value Lowered on Reassessment of Leqembi

Narrow-moat Biogen reported results that were in line with our expectations. Revenue guidance for 2025 is a mid-single-digit decline at constant currency, which we find slightly disappointing. We are lowering our fair value estimate to $220 per share from $303 due to lower forecasts for key drugs, especially Alzheimer’s drug Leqembi. There is a wide range of outcomes for its peak revenue. Still, due to its slow sales ramp and the potential for competing drugs to eventually enter this space, we adopt a more cautious view and lower our peak revenue forecast to $3 billion from $6 billion.