[Form 4] Repligen Corp Insider Trading Activity

Rhea-AI Filing Summary

Repligen Corp (RGEN) insider transaction summary. Olivier Loeillot, who serves as both Director and Chief Executive Officer, reported a transaction dated 09/03/2025 showing 2,506 shares of Repligen common stock were disposed of at a price of $116.18 per share. The filing explains these shares were withheld by the issuer to satisfy tax withholding obligations arising upon the release of restricted stock units. After the withholding, Loeillot beneficially owns 44,187 shares outright. The Form 4 was filed by one reporting person and signed on behalf of Loeillot by Jennifer Carmichael (Attorney in Fact) on 09/04/2025.

Positive

• Insider retains meaningful ownership: Olivier Loeillot continues to beneficially own 44,187 shares after withholding.
• Transaction is administrative: Shares were withheld to satisfy tax obligations on RSU release, not an open-market sale.

Negative

• Shares disposed via withholding: 2,506 shares were removed from the insider's direct holdings to cover taxes.

Insights

Corporate Governance Expert

TL;DR: Routine tax-withholding on RSU release; no change in role or control.

This appears to be a standard administrative disposition where shares were withheld to cover tax obligations when restricted stock units vested. The reporting person remains both CEO and a director and continues to hold a material stake of 44,187 shares directly. There is no indication of a voluntary sale or change in ownership strategy. For governance considerations, routine withholding is common and typically not a signal of insider-driven liquidity or governance shifts.

Securities Analyst

TL;DR: Transaction is non-economic withholding, not a market sale; impact on float is minimal.

The reported disposition of 2,506 shares at an effective price of $116.18 reflects shares retained by the issuer to satisfy tax withholdings tied to RSU vesting. Because this is a non-market transfer (issuer withholding), it does not reflect active selling pressure from the insider. Post-transaction direct beneficial ownership totals 44,187 shares, which retains insider alignment with shareholders. The event is informational and likely immaterial to short-term share supply dynamics.

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

OMB APPROVAL

OMB Number:			3235-0287
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hours per response:			0.5

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^*

Loeillot Olivier

(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)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
09/03/2025

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	09/03/2025		F		2,506(1)	D	$116.18	44,187	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)	09/04/2025
	** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What transaction did Olivier Loeillot report for RGEN on 09/03/2025?

He reported that 2,506 shares of Repligen common stock were disposed of via issuer withholding related to RSU tax obligations on 09/03/2025.

Why were the 2,506 shares disposed according to the Form 4?

The Form 4 explains the shares were withheld by the issuer to satisfy tax withholding obligations arising upon the release of restricted stock units.

How many Repligen shares does Loeillot beneficially own after the transaction?

After the withholding, Loeillot beneficially owns 44,187 shares of Repligen common stock.

What price is shown on the Form 4 for the withheld shares?

The Form 4 lists a price of $116.18 per share for the reported disposition.

Who signed the Form 4 and when was it signed?

The Form 4 was signed on behalf of Olivier Loeillot by Jennifer Carmichael (Attorney in Fact) on 09/04/2025.