Biogen will acquire pharmaceutical company Apellis for $5.6 billion.

Biogen has agreed to acquire Apellis Pharmaceuticals for $5.6 billion, expanding its treatment capabilities in the fields of immunology and rare diseases, marking one of the largest acquisitions in the company's history. The company will acquire Apellis at a price of $41 per share, more than double the latter's closing price on Monday. Apellis' stock has declined by 32% so far this year. Through this transaction, Biogen will gain access to two approved drugs. Apellis's best-selling drug is Syfovre, used to treat an immune system disease that can cause blindness, which generated revenue of $587 million last year. The other product is Empaveli, used to treat blood diseases and rare kidney diseases, with sales exceeding $100 million last year.