[Form 4] REPLIGEN CORP Insider Trading Activity

Rhea-AI Filing Summary

Repligen (RGEN) reported an insider transaction by a director on 11/12/2025. The director exercised 25,000 stock options at $33.87 and, on the same day, sold 25,000 common shares in multiple trades under a Rule 10b5-1 plan adopted on December 9, 2024. Sale prices were reported as weighted averages ranging from $154.92 to $158.51.

Following these transactions, the director directly owned 100,743 shares. The option reported expires on 03/01/2028, with 157,344 derivative securities beneficially owned after the transactions, and remaining tranches vesting 28,777 on 03/01/2026 and 28,778 on 03/01/2027.

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).

X

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^*

Hunt Anthony

(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
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
11/12/2025

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	11/12/2025		M		25,000	A	$33.87	125,743	D
Common Stock	11/12/2025		S(1)		3,741	D	$154.92(2)	122,002	D
Common Stock	11/12/2025		S(1)		4,740	D	$155.85(3)	117,262	D
Common Stock	11/12/2025		S(1)		4,959	D	$156.65(4)	112,303	D
Common Stock	11/12/2025		S(1)		11,096	D	$158.01(5)	101,207	D
Common Stock	11/12/2025		S(1)		464	D	$158.51(6)	100,743	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
Stock Option (Right to Buy)	$33.87	11/12/2025		M			25,000	(7)	03/01/2028	Common Stock	25,000	$0.00	157,344	D

Explanation of Responses:

1. Sale of common stock was effected pursuant to a 10(b)5-1 trading plan adopted on December 9, 2024.

2. $154.92 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $154.26 to $155.25, 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.

3. $155.85 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $155.28 to $156.28, 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.

4. $156.65 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $156.31 to $157.31, 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.

5. $158.01 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $157.41 to $158.39, 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.

6. $158.51 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $158.43 to $158.59, 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.

7. 207,344 of the shares underlying this option have vested. The remaining shares vest as follows: 28,777 shares on March 1, 2026, and 28,778 shares on March 1, 2027.

	/s/ Jennifer Carmichael (Attorney in Fact)	11/13/2025
	** 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 did the RGEN director transact on 11/12/2025?

Exercised 25,000 stock options at $33.87 and sold 25,000 common shares in multiple trades under a Rule 10b5-1 plan.

What sale prices were reported for the RGEN insider trades?

Weighted average prices ranged from $154.92 to $158.51, with detailed ranges provided for each tranche.

How many RGEN shares does the director own after the trades?

Direct ownership is 100,743 shares following the reported transactions.

What is the status of the RGEN stock option involved?

The option has an exercise price of $33.87, expires on 03/01/2028, and 157,344 derivative securities are beneficially owned after the transactions.

Was the RGEN insider trading under a 10b5-1 plan?

Yes. Sales were made under a Rule 10b5-1 trading plan adopted on December 9, 2024.

What are the remaining vesting dates for the reported RGEN option?

Remaining shares vest 28,777 on 03/01/2026 and 28,778 on 03/01/2027.