Key Highlights
- Biogen has entered into an agreement to purchase Apellis Pharmaceuticals for roughly $5.6 billion in an all-cash transaction.
- 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 to shareholders based on Syfovre sales performance.
- The transaction brings Biogen two commercial products, Empaveli and Syfovre, which collectively produced $689 million in sales last year.
- Completion of the acquisition is anticipated during Q2 2026.
Shares of Apellis Pharmaceuticals (APLS) rocketed more than 136% during pre-market hours on Tuesday, March 31, following Biogen’s (BIIB) announcement of its plan to acquire the specialty biopharmaceutical company for approximately $5.6 billion. Meanwhile, Biogen’s stock declined about 7% following the disclosure.
Apellis Pharmaceuticals, Inc., APLS
The $41 cash-per-share purchase price delivers a substantial premium of roughly 140% compared to APLS’s closing price from the prior trading day.
This strategic acquisition aligns with Biogen’s efforts to diversify its revenue streams beyond its aging multiple sclerosis franchise by expanding into immunology and rare disease therapeutics.
Apellis contributes two commercially approved medicines to Biogen’s pipeline. Empaveli has received authorization for treating two uncommon kidney conditions and a rare hematological disorder. Syfovre has been approved for geographic atrophy in its advanced stage, a significant contributor to vision loss globally.
The combined product portfolio generated around $689 million in revenue during 2025. Both companies anticipate this revenue stream will expand at a mid-to-high teens percentage rate annually through 2028 at minimum.
Milestone-Based Additional Payments
In addition to the upfront $41 per share acquisition price, Apellis shareholders stand to receive two separate contingent value payments of $2 each — potentially adding $4 per share to the total consideration — dependent upon achieving predetermined worldwide sales targets for Syfovre.
This structure could elevate the maximum total compensation to $45 per share upon successful milestone achievement.
Biogen’s CEO Christopher Viehbacher 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 is projected to finalize during the second quarter of 2026, subject to customary regulatory clearances and shareholder consent.
Biogen Shares Decline on News
While Apellis shareholders celebrated substantial gains, Biogen’s stock experienced downward pressure after the announcement, dropping approximately 7% in pre-market trading.
This market response is typical when an acquiring company pays a significant premium. Large-scale cash acquisitions often create near-term headwinds for the buyer’s stock price, especially when the transaction value reaches billions of dollars.
On TipRanks, BIIB holds 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 represents Biogen’s continued strategic pivot away from its traditional multiple sclerosis business toward higher-growth opportunities in the rare disease sector.
Prior to the acquisition announcement, Apellis shares were trading at approximately $17, based on the differential to the offered $41 per share purchase price.
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