Biogen BIIB and Apellis Pharmaceuticals APLS announced a definitive agreement under which Biogen will acquire all outstanding shares of Apellis for $41 per share in cash at closing. The offer represents a 140% premium to the day before closing price, valuing the transaction at approximately $5.6 billion. Following the announcement, APLS shares skyrocketed 135.4% on Tuesday.
The tender offer for the acquisition also includes a nontransferable contingent value right per share for Apellis stockholders, entitling the holder to receive two payments of $2 per share each, subject to the fulfillment of certain annual global net sales thresholds for Syfovre.
The impending acquisition will add Apellis’ two differentiated commercialized immunology medicines, Empaveli (pegcetacoplan) and Syfovre (pegcetacoplan injection), to Biogen’s portfolio.
In the United States, Empaveli is approved for paroxysmal nocturnal hemoglobinuria (PNH) in adults as well as for two rare kidney diseases, C3 glomerulopathy and primary immune-complex membranoproliferative glomerulonephritis in adults and adolescents. Outside the United States, the drug (Aspaveli in the EU) is marketed by Apellis’ partner Sobi for the PNH indication. On the other hand, Syfovre is currently approved in the United States and Australia for geographic atrophy secondary to age-related macular degeneration. Apellis has also completed a clinical study for a Syfovre prefilled syringe and plans to submit its application for FDA approval in the first half of 2026.
The Rationale for the Impending Acquisition Deal
The proposed acquisition of Apellis is expected to significantly strengthen Biogen’s growth trajectory by immediately expanding its portfolio in immunology and rare diseases. Apellis brings two commercially available, differentiated therapies — Empaveli and Syfovre — which together generated $689 million in net sales in 2025. These products are projected to grow at a mid-to-high teens rate through at least 2028, offering Biogen a near-term revenue boost alongside sustained long-term upside. The addition aligns with Biogen’s strategic pivot toward higher-growth therapeutic areas and enhances its ability to deliver more diversified and resilient revenue streams.
In the past six months, BIIB shares have gained 18.1%, while APLS shares have rallied 74% compared with the industry’s 9.5% growth.
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Beyond revenue contribution, the deal is expected to improve Biogen’s financial profile, with projections indicating a positive impact on earnings per share (EPS) beginning in 2027. The transaction is also anticipated to meaningfully increase Biogen’s adjusted EPS compounded annual growth rate through the end of the decade. With plans to finance the acquisition through a mix of cash and borrowings, Biogen aims to deleverage fully by 2027, preserving financial flexibility for future investments. This positions the company to pursue further strategic opportunities while maintaining a disciplined capital structure.
Strategically, Apellis’ established U.S. commercial infrastructure, especially its nephrology capabilities, is expected to enhance Biogen’s launch readiness for pipeline candidates like felzartamab, which is in late-stage development for three kidney diseases, with initial phase III data anticipated in 2027. Additionally, maintaining collaboration with partners like Sobi for ex-U.S. commercialization preserves operational continuity while enabling Biogen to concentrate on optimizing its commercial execution and market penetration in the United States.
Biogen Inc. Price and Consensus
Biogen Inc. price-consensus-chart | Biogen Inc. Quote
For Apellis, becoming part of Biogen provides access to significantly greater resources, global scale and an established commercial infrastructure. This is likely to accelerate the adoption of its therapies, expand geographic reach and support the advancement of its broader pipeline, ultimately amplifying its impact in complement-driven diseases.
The transaction is expected to close in the second quarter of 2026, contingent upon the successful completion of the tender offer, customary closing conditions and the receipt of necessary regulatory approvals.
Apellis Pharmaceuticals, Inc. Price and Consensus
Apellis Pharmaceuticals, Inc. price-consensus-chart | Apellis Pharmaceuticals, Inc. Quote
BIIB/APLS Zacks Rank & Stocks to Consider
Biogen and Apellis carry a Zacks Rank #3 (Hold) each at present.
Some better-ranked stocks in the biotech sector are Catalyst Pharmaceuticals CPRX and ADMA Biologics ADMA, each sporting a Zacks Rank #1 (Strong Buy) at present. You can see the complete list of today’s Zacks #1 Rank stocks here.
Over the past 60 days, estimates for Catalyst Pharmaceuticals’ 2026 EPS have decreased from $2.55 to $2.51. CPRX shares have gained 18.9% over the past six months.
Catalyst Pharmaceuticals’ earnings beat estimates in each of the trailing four quarters, with the average surprise being 35.19%.
Over the past 60 days, estimates for ADMA Biologics’ 2026 EPS have increased from 85 cents to 96 cents. ADMA shares have plummeted 37.9% over the past six months.
ADMA Biologics’ earnings beat estimates in one of the trailing three quarters, matched once and missed on the remaining occasion, with the average negative surprise being 1.79%.
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Biogen Inc. (BIIB): Free Stock Analysis Report
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ADMA Biologics Inc (ADMA): Free Stock Analysis Report
Apellis Pharmaceuticals, Inc. (APLS): Free Stock Analysis Report
This article originally published on Zacks Investment Research (zacks.com).