Key Highlights
- Biogen has reached an agreement to purchase 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 APLS’s previous closing price.
- Additional contingent value rights could provide shareholders with as much as $4 more per share based on Syfovre revenue targets.
- The transaction gives Biogen ownership of Empaveli and Syfovre, drugs that collectively earned $689 million in revenue during the prior year.
- Transaction completion is anticipated during Q2 2026.
Shares of Apellis Pharmaceuticals (APLS) exploded more than 136% during pre-market hours on Tuesday, March 31, following Biogen’s (BIIB) announcement of its plan to purchase the specialty pharmaceutical company for approximately $5.6 billion. Meanwhile, Biogen’s shares declined about 7% on the announcement.
Apellis Pharmaceuticals, Inc., APLS
The $41-per-share cash proposal from Biogen marks a substantial premium of roughly 140% compared to APLS’s closing price from the prior trading day.
This acquisition represents Biogen’s continuing effort to diversify away from declining sales in its multiple sclerosis franchise by expanding its presence in immunology and rare disease therapeutics.
Apellis contributes two commercially available medications to Biogen’s pipeline. Empaveli has regulatory approval for treating two uncommon kidney conditions plus a rare hematologic disorder. Syfovre addresses geographic atrophy in its advanced stage, a major contributor to vision loss globally.
The combined therapeutic portfolio generated roughly $689 million in total sales during 2025. Both companies anticipate continued revenue expansion in the mid-to-high teens percentage annually through 2028 at minimum.
Additional Milestone-Based Compensation Structure
In addition to the initial $41-per-share payment, Apellis shareholders stand to gain two separate contingent payments worth $2 apiece — potentially adding $4 per share — tied to achieving designated worldwide revenue benchmarks for Syfovre.
This structure means shareholders could ultimately receive up to $45 per share if performance targets are successfully met.
Christopher Viehbacher, Biogen’s CEO, characterized the deal 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 faces standard regulatory review and shareholder approval procedures, with completion targeted for the second quarter of 2026.
Biogen Shares Decline on Announcement
While shareholders of APLS celebrated significant gains, Biogen’s stock faced downward pressure after the disclosure, dropping approximately 7% in pre-market activity.
Such negative reactions are typical for acquiring companies offering significant premiums. Multi-billion dollar cash acquisitions frequently create near-term headwinds for the purchaser’s equity valuation.
On TipRanks, BIIB carries a Moderate Buy consensus rating based on 11 Buy, 15 Hold, and 1 Sell analyst ratings. The consensus price target sits at $206.70, implying around 10% upside from recent levels, with the highest target at $250.
This transaction marks Biogen’s most recent strategic initiative to pivot from its traditional MS-focused business model toward accelerated growth opportunities in rare disease therapeutics.
Prior to the takeover announcement, Apellis shares were trading near $17, based on the discount implied by the $41-per-share acquisition price.
