---
schema_version: "secwatch.filing_event.v1"
accession: "0000875045-25-000014"
form_type: "8-K"
ticker: "BIIB"
cik: "0000875045"
company_name: "BIOGEN INC."
filed_at: "2025-05-01T23:59:59+00:00"
generated_at: "2026-05-23T01:35:48.859455+00:00"
event_type: "earnings"
sentiment: "neutral"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Biogen Q1 revenue up 6% to $2.43B; Non-GAAP EPS $3.02 impacted by $165M Stoke upfront

## Summary
- GAAP diluted EPS $1.64, Non-GAAP $3.02; both down YoY due to ~($0.95) impact from Stoke upfront payment.
- LEQEMBI global in-market sales ~$96M; SKYCLARYS global revenue ~$124M; launch products more than doubled YoY.
- Updated FY2025 non-GAAP EPS guidance $14.50-$15.50; total revenue expected to decline mid-single-digit constant currency.
- Felzartamab Phase 3 study initiated in antibody-mediated rejection; BIIB080 (tau ASO) received FDA Fast Track designation.
- Zorevunersen collaboration with Stoke ($165M upfront) for Dravet syndrome; pivotal Phase 3 to start in coming months.

## SEC filing metadata
- accession: 0000875045-25-000014
- form_type: 8-K
- ticker: BIIB
- cik: 0000875045
- company_name: BIOGEN INC.
- filed_at: 2025-05-01T23:59:59+00:00
- event_type: earnings
- sentiment: neutral
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 2.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/875045/000087504525000014/0000875045-25-000014-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/875045/000087504525000014/biib-20250501.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000875045-25-000014
- JSON: https://secwatch.observer/filing/0000875045-25-000014.json
- Plain text: https://secwatch.observer/filing/0000875045-25-000014.txt

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