[Form 4] REPLIGEN CORP Insider Trading Activity

Rhea-AI Filing Summary

Repligen Corporation's Chief Operating Officer reported a stock sale in a Form 4. On 11/18/2025, the officer sold 2,191 shares of Repligen common stock in an open market transaction coded "S" (sale). The weighted average sale price was $151.21 per share, with individual trades executed between $151.21 and $151.62.

After this transaction, the officer directly beneficially owns 21,520 shares of Repligen common stock. The filing notes that detailed trade breakdowns by price within the range are available upon request from the company, its security holders, or the SEC staff.

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
Estimated average burden
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^*

Bylund James

(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 Operating Officer

3. Date of Earliest Transaction (Month/Day/Year)
11/18/2025

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	11/18/2025		S		2,191	D	$151.21(1)	21,520	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. $151.21 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $151.21 to $151.62, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range.

	/s/ Jennifer Carmichael (Attorney in Fact)	11/19/2025
	** 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 insider transaction did Repligen (RGEN) report in this Form 4?

The Chief Operating Officer of Repligen Corporation (RGEN) reported an open market sale of 2,191 shares of the company’s common stock on 11/18/2025.

At what price were the Repligen (RGEN) shares sold in the reported transaction?

The 2,191 shares were sold at a weighted average price of $151.21 per share, in multiple trades at prices ranging from $151.21 to $151.62, inclusive.

How many Repligen (RGEN) shares does the insider own after this sale?

Following the reported sale, the Repligen Chief Operating Officer directly beneficially owns 21,520 shares of the company’s common stock.

What is the role of the reporting person in Repligen (RGEN)?

The reporting person in this Form 4 is an officer of Repligen Corporation, serving as the company’s Chief Operating Officer.

Does the Form 4 for Repligen (RGEN) provide details of each individual trade price?

The filing states that the weighted average price is $151.21 and that trades occurred between $151.21 and $151.62. The reporting person undertakes to provide full information on the number of shares sold at each separate price within that range upon request.

What transaction code is used in the Repligen (RGEN) Form 4 filing?

The transaction is identified with code "S", which denotes an open market or private sale of non-derivative securities by the insider.