Key Highlights
- Biogen is purchasing Apellis Pharmaceuticals in an all-cash transaction valued at roughly $5.6 billion.
- The acquisition 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 revenue targets.
- The transaction adds Empaveli and Syfovre to Biogen’s portfolio, drugs that collectively earned $689 million in revenue during the previous year.
- Transaction completion is anticipated during Q2 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 intent to purchase the specialty pharmaceutical company for approximately $5.6 billion. Meanwhile, Biogen’s shares declined around 7% following the disclosure.
Apellis Pharmaceuticals, Inc., APLS
The $41 cash payment per share that Biogen has proposed delivers roughly a 140% premium over APLS’ closing price from the prior trading session.
This strategic acquisition aligns with Biogen’s broader initiative to diversify its revenue streams beyond its aging multiple sclerosis franchise by strengthening its presence in immunology and rare disease therapeutics.
Apellis contributes two commercially available therapies to Biogen’s arsenal. Empaveli has received approval for treating two uncommon kidney conditions along with a rare hematologic disorder. Syfovre addresses geographic atrophy in its advanced stages, a condition responsible for significant vision loss globally.
The combined revenue from these two products reached approximately $689 million throughout 2025. Both companies anticipate this figure will expand at a mid-to-high teens percentage rate annually through 2028 at minimum.
Additional Milestone-Based Payments Structure
In addition to the headline $41 per share purchase price, Apellis shareholders stand to gain two separate contingent payments valued at $2 apiece — potentially adding $4 per share total — dependent upon achieving predetermined worldwide sales targets for Syfovre.
This structure establishes a maximum potential value of $45 per share should all performance benchmarks be satisfied.
Christopher Viehbacher, Biogen’s Chief Executive Officer, 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 closing targeted for the second quarter of 2026.
Biogen Shares Face Pressure
While Apellis shareholders celebrated substantial gains, Biogen’s stock faced selling pressure after the announcement, dropping approximately 7% in pre-market activity.
Such reactions are typical when acquiring companies pay significant premiums. Multi-billion dollar all-cash acquisitions frequently pressure the buyer’s stock price in the immediate aftermath, especially at this scale.
On TipRanks, BIIB holds a Moderate Buy consensus rating derived from 11 Buy, 15 Hold, and 1 Sell recommendations from analysts. The average price target stands at $206.70, suggesting approximately 10% potential upside from current levels, with a high-end estimate of $250.
This acquisition represents Biogen’s continued effort to pivot from its traditional multiple sclerosis-focused business model toward faster-growing rare disease therapeutic areas.
Apellis shares closed at roughly $17 before the deal announcement, based on the differential to the $41 per share acquisition price.
