Apellis Leads Trading Activity Despite Sharp Volume Drop as Biogen's $5.6 Billion Takeover Drives Pre-Market Surge

Market Snapshot

Apellis (APLS) closed on April 1, 2026, with a modest gain of 0.40%, despite experiencing a significant drop in trading volume. The company’s stock saw a trading volume of $1.23 billion, a decline of 66.44% compared to the previous day. This drop in volume was notable as Apellis ranked first in overall trading activity for the day. While the price movement was relatively small, the sharp decline in volume may reflect a shift in short-term investor activity following the announcement of its pending acquisition by Biogen.

Key Drivers

Apellis’ stock surged more than 130% in pre-market trading following the announcement that Biogen has agreed to acquire the company in a $5.6 billion all-cash deal. The proposed transaction represents a 140% premium over Apellis’ stock price at the close of March 30, 2026, and is structured around $41 per share in cash at closing. Additionally, Apellis shareholders are eligible for a contingent value right (CVR), entitling them to receive up to $4 per share in additional payments contingent on future sales milestones for Apellis’ Syfovre, its flagship treatment for geographic atrophy, a rare form of advanced macular degeneration.

The acquisition is part of Biogen’s broader strategy to strengthen its immunology and rare disease portfolio, particularly in nephrology. Biogen’s CEO, Chris Viehbacher, has emphasized the need to diversify and expand the company’s revenue sources as its older products, such as its multiple sclerosis franchise and Alzheimer’s drug, face challenges. Apellis’ two commercial products—Syfovre and Empaveli—are expected to significantly bolster Biogen’s growth profile. Syfovre, which generated $587 million in revenue in 2025, is used to treat a rare immune-mediated retinal disease, while Empaveli, a treatment for rare kidney and blood disorders, added over $100 million in sales in the same period.

The deal also aligns with Biogen’s long-term interest in expanding into nephrology. Empaveli’s application in rare kidney diseases complements Biogen’s existing late-stage pipeline, particularly its drug felzartamab, which is currently being tested for similar conditions. The acquisition will allow Biogen to leverage Apellis’ commercial infrastructure and expertise to accelerate the development and potential launch of its own nephrology candidates. This strategic move positions Biogen to capitalize on the growing demand for therapies in the rare disease and immunology spaces, which are known for high-margin and long-term revenue potential.

The proposed transaction has been widely viewed as a major milestone in Biogen’s M&A strategy, following its $7.3 billion acquisition of Reata Pharmaceuticals in 2023 and a $1.8 billion deal with Human Immunology Biosciences in 2024. These acquisitions have collectively demonstrated Biogen’s intent to strengthen its pipeline through inorganic growth, particularly in rare diseases and immunology. Analysts note that the Apellis deal is a continuation of this trend, offering both immediate revenue accretion and long-term therapeutic expansion.

Despite the premium offered, Biogen’s stock initially declined in response to the news, with shares falling over 4% on April 1. This reaction suggests that some investors may be questioning the valuation or the broader implications for Biogen’s balance sheet. However, the company has indicated it will fund the deal through a combination of cash reserves and new debt, suggesting confidence in its ability to manage the transaction without significantly disrupting its financial structure.

Looking ahead, the deal is expected to close in the second quarter of 2026, following regulatory approvals. Once completed, it will immediately add two commercial products to Biogen’s portfolio and expand its presence in rare diseases and immunology. The transaction also reflects the broader trend of consolidation in the biotechnology sector, as companies seek to secure high-value assets in therapeutic areas with strong growth potential.