Repligen (RGEN) CPO has shares withheld to cover RSU tax bill

Rhea-AI Filing Summary

Repligen Corp chief product officer Brian Robb reported a small share disposition tied to taxes rather than an open-market trade. On the reported date, 221 shares of common stock were withheld by the company at $124.97 per share to cover tax obligations arising from the release of restricted stock units. After this tax-withholding transaction, Robb’s directly held common stock balance was 8,319 shares.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Douglass Brian Robb

(Last) (First) (Middle)

C/O REPLIGEN CORPORATION

41 SEYON ST., BLDG 1, STE 100

(Street)

WALTHAM MA 02453

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
REPLIGEN CORP [ RGEN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	CHIEF PRODUCT OFFICER

3. Date of Earliest Transaction (Month/Day/Year)
03/02/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/02/2026		F		221(1)	D	$124.97	8,319	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. 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.

	/s/ Jennifer Carmichael (Attorney in Fact)	03/03/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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FAQ

What insider transaction did Repligen (RGEN) report for Brian Robb?

Repligen reported a small insider disposition for Brian Robb. The company withheld 221 shares of common stock to cover tax obligations triggered by the release of restricted stock units, rather than an open-market sale, leaving him with 8,319 directly held shares.

How many Repligen (RGEN) shares were withheld for Brian Robb’s taxes?

Repligen withheld 221 shares for Brian Robb’s tax obligations. These shares were retained by the company when restricted stock units vested, serving as payment for taxes due instead of a cash outlay, and are reported as a disposal on the Form 4.

At what price were Brian Robb’s Repligen (RGEN) shares withheld?

The withheld Repligen shares were valued at $124.97 per share. This price is used solely for reporting the tax-withholding disposition related to restricted stock units and does not represent an open-market trade executed by the chief product officer.

How many Repligen (RGEN) shares does Brian Robb hold after this Form 4?

After the reported tax-withholding transaction, Brian Robb directly holds 8,319 Repligen common shares. This figure reflects his remaining ownership following the 221-share withholding used to satisfy tax liabilities on vested restricted stock units.

Was Brian Robb’s Repligen (RGEN) Form 4 an open-market sale?

No, the Form 4 reflects tax withholding rather than an open-market sale. Repligen retained 221 shares to cover Brian Robb’s tax liability upon restricted stock unit release, which is reported as a disposal but not a discretionary sale into the market.