RGEN · Repligen Corp

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2025.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 8, 2025.

Ms. Pax was awarded 995 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 14, 2027, 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.

Ms. Dawes was awarded 995 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 14, 2027, 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 14, 2027, 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.

Mr. Mhatre was awarded 995 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 14, 2027, 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.

Mr. Konstantinov was awarded 995 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 14, 2027, 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.

Mr. Barthelemy was awarded 995 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 14, 2027, 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 Reporting Person has elected to defer settlement of these restricted stock units pursuant to the Repligen Corporation Deferred Compensation Plan for Non-Employee Directors. Once vested, the shares will be issued in accordance with the Reporting Person's deferral election following the separation of the Reporting Person's service as a Director. 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 14, 2027, 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.

Ms. Manner was awarded 995 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 14, 2027, 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 14, 2027, 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.

Award vests in full on the earlier of May 14, 2027, 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.

Mr. Madaus was awarded 995 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 14, 2027, 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 Reporting Person has elected to defer settlement of these restricted stock units pursuant to the Repligen Corporation Deferred Compensation Plan for Non-Employee Directors. Once vested, the shares will be issued in accordance with the Reporting Person's deferral election following the separation of the Reporting Person's service as a Director. 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 14, 2027, 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.

Award vests in full on the earlier of May 14, 2027, 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.

Award vests in full on the earlier of May 14, 2027, 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.

Award vests in full on the earlier of May 14, 2027, 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.

Mr. Muir was awarded 995 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 14, 2027, 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 Reporting Person has elected to defer settlement of these restricted stock units pursuant to the Repligen Corporation Deferred Compensation Plan for Non-Employee Directors. Once vested, the shares will be issued in accordance with the Reporting Person's deferral election following the separation of the Reporting Person's service as a Director. 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.

This option is fully vested and exercisable.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Sale of common stock was effected pursuant to a 10(b)5-1 trading plan adopted on August 19th, 2025.

One third of the stock options will vest and become exercisable annually on March 5, 2027, March 5, 2028, and March 5, 2029.

One third of the stock options will vest and become exercisable annually on March 5, 2027, March 5, 2028, and March 5, 2029.

Mr. Garland was awarded 7,751 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 in equal annual instalments over a three-year period beginning on the first anniversary of 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.

Mr. Bylund was awarded 7,751 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 in equal annual instalments over a three-year period beginning on the first anniversary of 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.

Mr. Loeillot was awarded 24,134 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 in equal annual instalments over a three-year period beginning on the first anniversary of 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.

One third of the stock options will vest and become exercisable annually on March 5, 2027, March 5, 2028, and March 5, 2029.

Mr. Kuriyel was awarded 5,284 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 in equal annual instalments over a three-year period beginning on the first anniversary of 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.

One third of the stock options will vest and become exercisable annually on March 5, 2027, March 5, 2028, and March 5, 2029.

Represents 125 shares issued pursuant to a Performance Stock Unit ("PSU") award granted to the Issuer on January 1, 2025. The Compensation Committee authorized the issuance of the underlying shares based upon the Issuer's achievement of pre-established performance criteria set forth in the PSU award.

Represents 125 shares issued pursuant to a Performance Stock Unit ("PSU") award granted to the Issuer on January 1, 2025. The Compensation Committee authorized the issuance of the underlying shares based upon the Issuer's achievement of pre-established performance criteria set forth in the PSU award.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of the performance stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of the performance stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

Represents the number of shares withheld by the Issuer to satisfy tax withholding obligations of the reporting person that arose upon the release of restricted stock units.

The shares will vest in substantially equal installments over a three-year period with each such vesting date occurring on the anniversary of the grant date.

Mr. Douglass was awarded 2,288 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 in substantially equal annual instalments over a three-year period beginning on the first anniversary of the grant date. The restricted stock units may be settled only by delivering shares of Repligen Corporation's Common Stock.

This option is fully vested and exercisable.

Represents a transfer of shares for which the Reporting Person is a joint tenant with right of survivorship.