Why Is Apellis Stock Skyrocketing Tuesday? - Apellis Pharmaceuticals (NASDAQ:APLS), Biogen (NASDAQ:BIIB)
Apellis Pharmaceuticals' stock is skyrocketing after Biogen announced its intent to acquire the company for $41 per share in cash, totaling approximately $5.6 billion. This acquisition is expected to bolster Biogen's immunology and rare disease portfolio, particularly with Apellis's FDA-approved therapies Empaveli and Syfovre, which generated $689 million in combined net sales in 2025. The deal includes a contingent value right for Apellis shareholders and is projected to enhance Biogen's revenue and adjusted earnings per share starting in 2027.
How this was made

The 30-second read
Why it matters
The deal is expected to boost Biogen's revenue and earnings from 2027 onwards, signaling confidence in Apellis's therapies.
Market read
The acquisition is a significant event in the biotech sector, likely influencing stock prices and M&A activity.
What to watch
Potential integration challenges and regulatory hurdles could temper long-term gains.
Background
Biogen's strategic move to acquire Apellis aims to strengthen its portfolio in immunology and rare diseases.
Ticker impact
Primary focus due to acquisition news.
Potential for immediate upward movement, possibly exceeding the acquisition price in the short term.
The deal's announced premium and strategic value suggest strong positive sentiment and immediate price reaction.
Secondary impact as a result of the acquisition.
Moderate upward movement expected, contingent on market perception of strategic fit.
Market reaction depends on investor confidence in integration and future growth prospects.
Market effects
Potential uplift in biotech and immunology sectors due to increased M&A activity.
Likely positive impact on US biotech stocks, with possible ripple effects in global markets.
Moderate, as the deal involves US-based companies with significant international operations.
Counterpoint
The acquisition premium may already be priced in, and short-term gains could be limited or followed by a correction.
Key entities
- CompanyApellis Pharmaceuticals
Biotech company specializing in immunology and rare disease therapies.
- CompanyBiogen
Global biotech firm focusing on neuroscience, immunology, and rare diseases.

