---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-134889"
form_type: "8-K"
ticker: "BIIB"
cik: "0000875045"
company_name: "BIOGEN INC."
filed_at: "2026-03-31T23:59:59+00:00"
generated_at: "2026-05-15T08:18:56.546731+00:00"
event_type: "m_and_a"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Biogen to acquire Apellis for $41/share plus up to $4 CVR per share

## Summary
- Upfront cash consideration of $41.00 per Apellis share; one CVR per share entitling holders to up to $4.00 additional.
- CVR milestones: $2.00 if SYFOVRE annual net sales reach $1.5B; $2.00 if $2.0B achieved, with potential $4.00 single payment.
- Tender offer condition requires >50% shares tendered; termination fee of $205M payable by Apellis in certain circumstances.
- Stockholders representing ~14% of Apellis shares entered support agreement to tender in favor.
- Transaction expected to close by September 30, 2026, subject to regulatory approvals and other conditions.

## SEC filing metadata
- accession: 0001193125-26-134889
- form_type: 8-K
- ticker: BIIB
- cik: 0000875045
- company_name: BIOGEN INC.
- filed_at: 2026-03-31T23:59:59+00:00
- event_type: m_and_a
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 1.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/875045/000119312526134889/0001193125-26-134889-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/875045/000119312526134889/d14986d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-134889
- JSON: https://secwatch.observer/filing/0001193125-26-134889.json
- Plain text: https://secwatch.observer/filing/0001193125-26-134889.txt

## Key facts
- Material Agreements
  BIOGEN INC. entered into Merger Agreement with Apellis Pharmaceuticals, Inc. valued at $41.00 per share of Apellis Common Stock (effective 2026-03-31).
  - Action: entry
  - Agreement: merger
  - Counterparty: Apellis Pharmaceuticals, Inc.
  - Value: $41.00 per share of Apellis Common Stock
  - Effective: 2026-03-31
  source text: On March 31, 2026, Biogen Inc., a Delaware corporation (“Biogen”), entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Apellis Pharmaceuticals, Inc., a Delaware corporation (“Apellis”), and Aspen Purchaser Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Biogen (“Purchaser”).
  evidence_url: https://www.sec.gov/Archives/edgar/data/875045/000119312526134889/0001193125-26-134889-index.htm

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.