Biogen, Inc. to acquire BIOG portfolio company, Apellis Pharmaceuticals, Inc.

1 April 2026

THE BIOTECH GROWTH TRUST PLC

("BIOG" or the "Company")

Biogen, Inc. to acquire BIOG portfolio company, Apellis Pharmaceuticals, Inc.

The Company notes the announcement on Tuesday, 31 March 2026 that Biogen Inc. ("Biogen") has entered into an agreement to acquire BIOG portfolio company, Apellis Pharmaceuticals, Inc. ("Apellis") for approximately $5.6 billion, or $41 per share, in cash, representing a 140% premium to Apellis' closing price on Monday, 30 March 2026.   The offer also includes an additional $4 per share of contingent value right payments which are based on Apellis products achieving certain sales milestones;   if met, the aggregate purchase price would represent a 163% premium to Apellis' closing price on Monday, 30 March 2026.

Apellis is a global biopharmaceutical company focused on drugs targeting the complement pathway for diseases of the eye, blood and kidney.   Apellis launched the first new class of complement medicines in 15 years and now has two C3-targeted drugs, EMPAVELI and SYFOVRE, approved to treat four serious diseases.   The drugs include the first-ever therapy for geographic atrophy, a leading cause of blindness, and a drug to treat complement 3 glomerulopathy (C3G), a severe rare kidney disease.   Net product revenues for EMPAVELI and SYFOVRE totalled $689 million in 2025 and Apellis expects revenue for these products to grow in the mid-to-high teens at least through 2028.

The Company's holding in Apellis represented 1.74% of the Company's net asset value at the time of the announcement.   The transaction will be reflected in the Company's NAV as at close of business on 31 March 2026, which will be announced later today.

To sign up for BIOG updates by email, please click here .

Enquiries:

SEC Newgate (George Esmond)

Public Relations

020 3757 6894

Frostrow Capital LLP

Company Secretary

020 3709 8734

---

---