Officer/Director Change

Karen A. Dawes notified Repligen Corporation of her retirement from the Board of Directors, effective September 30, 2026. Ms. Dawes has served on the Board for over twenty years. Her decision to retire is not due to any disagreement with the company's operations, policies, or procedures. She expressed pride in Repligen's accomplishments and confidence in the company's future leadership and growth potential, especially following a successful CEO transition. The filing also notes that the company's common stock is traded on the Nasdaq Global Select Market.