Key Highlights
- Biogen will acquire Apellis Pharmaceuticals in an all-cash transaction valued at approximately $5.6 billion.
- The offer price of $41 per share represents approximately a 140% premium over Apellis’ previous closing price.
- Additional contingent value rights could deliver up to $4 per share based on Syfovre achieving specific sales targets.
- The acquisition adds Empaveli and Syfovre to Biogen’s portfolio, drugs that collectively earned $689 million in revenue during 2025.
- Transaction completion is anticipated during the second quarter of 2026.
Shares of Apellis Pharmaceuticals (APLS) skyrocketed more than 136% during pre-market hours on Tuesday, March 31, following Biogen’s (BIIB) announcement of its intention to purchase the specialty pharmaceutical company for approximately $5.6 billion. Meanwhile, Biogen shares declined around 7% in early trading.
Apellis Pharmaceuticals, Inc., APLS
The $41-per-share cash offer from Biogen delivers a substantial premium of roughly 140% above the level where APLS shares finished the prior trading day.
This strategic acquisition aligns with Biogen’s broader initiative to diversify revenue streams beyond its aging multiple sclerosis franchise by strengthening its presence in immunology and rare disease therapeutics.
The acquisition grants Biogen control of two commercially available therapeutics. Empaveli has received regulatory approval for treating two uncommon kidney conditions along with a rare hematological disorder. Syfovre addresses geographic atrophy in its advanced stages, a significant contributor to vision loss globally.
During 2025, these two products generated combined sales of roughly $689 million. Both companies forecast annual revenue growth in the mid-to-high teens percentage range extending through 2028 at minimum.
Additional Milestone-Based Compensation Structure
Along with the $41 base offer, Apellis shareholders stand to gain two separate milestone payments of $2 each — potentially adding $4 per share — should Syfovre achieve predetermined worldwide sales benchmarks.
This structure creates a maximum potential value of $45 per share when including all possible milestone payments.
Christopher Viehbacher, Chief Executive Officer of Biogen, characterized the transaction as aligned with the company’s strategic evolution. “The addition of Apellis expands our growth portfolio in immunology and rare disease with two approved, best-in-class medicines that complement our existing portfolio,” he stated.
The transaction awaits customary regulatory clearances and shareholder votes, with an expected closing date in the second quarter of 2026.
Acquirer Shares Face Downward Pressure
While Apellis shareholders experienced substantial gains, Biogen’s stock price faced downward momentum after the deal announcement, dropping approximately 7% in pre-market trading.
This market response is common when acquiring companies offer significant premiums. Multi-billion dollar cash acquisitions frequently create near-term pressure on the purchasing company’s share price.
On TipRanks, BIIB holds a Moderate Buy consensus rating derived from 11 Buy, 15 Hold, and 1 Sell recommendations among analysts. The average price target stands at $206.70, suggesting approximately 10% potential appreciation from current levels, with the most optimistic forecast reaching $250.
This transaction represents another significant step in Biogen’s transformation away from its traditional MS-focused business model toward faster-growing rare disease therapeutic areas.
Apellis shares traded at roughly $17 before the acquisition announcement, based on the substantial discount to the $41 offer price.
