---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-003467"
form_type: "8-K"
ticker: "RGEN"
cik: "0000730272"
company_name: "REPLIGEN CORP"
filed_at: "2026-01-06T23:59:59+00:00"
generated_at: "2026-05-16T11:35:35.226317+00:00"
event_type: "leadership"
sentiment: "neutral"
materiality_score: 0.5
calibrated_materiality_score: 0.5
confidence: "high"
source: SEC EDGAR
---

# Repligen elects Martin D. Madaus as Chair, succeeding Tony Hunt effective Mar 13, 2026

## Summary
- Tony Hunt retires as Executive Chair and Board member effective March 13, 2026; will serve as advisor through March 2027.
- Dr. Martin D. Madaus, a director since February 2023, elected as Chair of the Board effective March 13, 2026.
- Madaus brings 36 years of bioprocessing industry experience; formerly Chairman, President and CEO of Millipore.
- The succession was previously disclosed in Repligen's June 14, 2024 8-K filing.

## SEC filing metadata
- accession: 0001193125-26-003467
- form_type: 8-K
- ticker: RGEN
- cik: 0000730272
- company_name: REPLIGEN CORP
- filed_at: 2026-01-06T23:59:59+00:00
- event_type: leadership
- sentiment: neutral
- materiality_score: 0.5
- calibrated_materiality_score: 0.5
- confidence: high
- sec_items: 5.02, 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/730272/000119312526003467/0001193125-26-003467-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/730272/000119312526003467/rgen-20260106.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-003467
- JSON: https://secwatch.observer/filing/0001193125-26-003467.json
- Plain text: https://secwatch.observer/filing/0001193125-26-003467.txt

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