X0306 4 2021-05-13 0 0000730272 REPLIGEN CORP RGEN 0001283576 BARTHELEMY NICOLAS C/O REPLIGEN CORPORATION 41 SEYON ST., BLDG 1, STE 100 WALTHAM MA 02453 1 0 0 0 Common Stock 2021-05-13 4 A 0 457 0.00 A 1907 D Stock Option (Right to Buy) 169.65 2021-05-13 4 A 0 1151 0.00 A 2022-05-13 2031-05-13 Common Stock 1151 1151 D Mr. Barthelemy was awarded 457 restricted stock units. Each restricted stock unit represents a contingent right to receive one share of Repligen Corporation's Common Stock. The restricted stock units vest on the earlier of May 13, 2022, one year from the grant date, or the date of the next annual meeting of the Company's shareholders, which has not yet been determined. The restricted stock units may be settled only by delivering shares of Repligen Corporation's Common Stock, and thus, the grant is being reported in Table 1 as allowed per SEC guidance. Award vests in full on the earlier of May 13, 2022, one year from grant date, or on the date of the next annual meeting of the Company's shareholders, which has not yet been determined. Exhibit 24.1: Power of Attorney /s/ Kimberly Brown (Attorney in Fact) 2021-05-17