X0306 4 2022-05-26 0 0000730272 REPLIGEN CORP RGEN 0001774649 Konstantinov Konstantin C/O REPLIGEN CORPORATION 41 SEYON ST., BLDG 1, STE 100 WALTHAM MA 02453 1 0 0 0 Common Stock 2022-05-26 4 A 0 534 0.00 A 534 D Stock Option (Right to Buy) 159.17 2022-05-26 4 A 0 1298 0.00 A 2023-05-26 2032-05-26 Common Stock 1298 1298 D Stock Option (Right to Buy) 159.17 2022-05-26 4 A 0 2498 0.00 A 2023-05-26 2032-05-26 Common Stock 2498 2498 D Mr. Konstantinov was awarded 534 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 May 26, 2023, one year from the grant date. 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 May 26, 2023, one year from grant date. The shares vest in equal annual instalments over a three-year period with each such vesting date occurring on the earlier of the anniversary of the grant date or the date of the annual meeting of the Company's shareholders of the applicable year of such three-year period. /s/ Kimberly Brown (Attorney in Fact) 2022-05-31