Repligen (RGEN) CPO has 334 RSU shares withheld to cover taxes

Rhea-AI Filing Summary

Repligen Corp chief product officer Brian Robb had 334 common shares withheld on the release of restricted stock units, at a value of $126.43 per share. These shares were retained by the company to cover his tax obligations, not sold on the open market, leaving him with 7,985 shares held directly.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Douglass Brian Robb

Role CHIEF PRODUCT OFFICER

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock	334	$126.43	$42K

Holdings After Transaction: Common Stock — 7,985 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Shares withheld for taxes: 334 shares Per-share value: $126.43 per share Shares held after transaction: 7,985 shares +1 more

4 metrics

Shares withheld for taxes 334 shares Common stock withheld to satisfy tax obligations on RSU release

Per-share value $126.43 per share Value used for the 334 withheld shares

Shares held after transaction 7,985 shares Brian Robb’s direct common stock holdings following withholding

Tax-withholding transactions 1 transaction, 334 shares Summary of tax-withholding disposition events in this Form 4

Key Terms

restricted stock units, tax withholding obligations, tax-withholding disposition, Form 4

4 terms

restricted stock units financial

"arose upon the release of restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax withholding obligations financial

"withheld by the Issuer to satisfy tax withholding obligations"

tax-withholding disposition financial

"transaction_action: "tax-withholding disposition""

A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.

Form 4 regulatory

"INSIDER FILING DATA (Form 4):"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

Form 4 Insider Transactions: What Each Field Means →

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^*

Douglass Brian Robb

(Last) (First) (Middle)

C/O REPLIGEN CORPORATION

41 SEYON ST., BLDG 1, STE 100

(Street)

WALTHAM MASSACHUSETTS 02453

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/07/2026

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

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

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

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	05/07/2026		F		334(1)	D	$126.43	7,985	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)	05/08/2026
	** 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).
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.
* Form 4: SEC 1474 (03-26)

FAQ

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

REPLIGEN CORP reported that chief product officer Brian Robb had 334 common shares withheld to cover tax obligations. The shares were tied to the release of restricted stock units and were not sold in the open market, reflecting a routine compensation-related adjustment.

How many REPLIGEN CORP (RGEN) shares were withheld for taxes in this Form 4?

A total of 334 REPLIGEN CORP common shares were withheld to satisfy Brian Robb’s tax obligations. The shares relate to vested restricted stock units and are treated as a tax-withholding disposition, rather than a discretionary sale or purchase in the open market.

At what price were the withheld REPLIGEN CORP (RGEN) shares valued?

The 334 withheld shares were valued at $126.43 per share for tax purposes. This valuation reflects the share price used to calculate the tax obligation when restricted stock units were released, rather than a separate open-market trade or negotiated sale transaction.

How many REPLIGEN CORP (RGEN) shares does Brian Robb hold after this transaction?

After the tax-withholding transaction, Brian Robb holds 7,985 REPLIGEN CORP common shares directly. This figure represents his remaining equity position reported in the Form 4, following the withholding of shares to cover taxes on restricted stock unit vesting.

Was this REPLIGEN CORP (RGEN) Form 4 an open-market sale by Brian Robb?

No, the Form 4 shows a tax-withholding disposition, not an open-market sale. Shares were withheld by REPLIGEN CORP to satisfy Brian Robb’s tax obligations on restricted stock units that were released, a standard mechanism for handling equity-based compensation taxes.