Biogen is acquiring RayThera in a deal valued at up to $1 billion to add small-molecule immunology assets to its pipeline. The companies said Biogen will provide an undisclosed upfront payment, with most value tied to future clinical and regulatory milestones. RayThera’s lead program is expected to enter Phase I in early Q3 2026, giving Biogen a near-term clinical opportunity to advance a new immunology candidate. Biogen highlighted that RayThera’s portfolio could broaden opportunities across immune-mediated conditions beyond its existing immunology footprint. The transaction follows Biogen’s recent push in immunology through other acquisitions, underscoring continued portfolio diversification as it looks to deepen pipeline coverage across therapeutic areas.