# EDGAR Filing Document

**Accession Number:** 0000730272
**File Stem:** 0000899243-23-004317
**Filing Date:** 2023-2
**Character Count:** 6290
**Document Hash:** 22804da90186d931daf62ab91471facd
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000899243-23-004317.hdr.sgml**: 20230208

**ACCESSION NUMBER**: 0000899243-23-004317

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20230206

**FILED AS OF DATE**: 20230208

**DATE AS OF CHANGE**: 20230208

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Madaus Martin D
- **CENTRAL INDEX KEY:** 0001310268

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-14656
- **FILM NUMBER:** 23600339

**MAIL ADDRESS:**
- **STREET 1:** 290 CONCORD ROAD
- **CITY:** BILLERICA
- **STATE:** MA
- **ZIP:** 01821
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** REPLIGEN CORP
- **CENTRAL INDEX KEY:** 0000730272
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **IRS NUMBER:** 042729386
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 41 SEYON STREET
- **STREET 2:** BUILDING 1, SUITE 100
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02453
- **BUSINESS PHONE:** 7814499560

**MAIL ADDRESS:**
- **STREET 1:** 41 SEYON STREET
- **STREET 2:** BUILDING 1, SUITE 100
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02453

## Exhibit 24.1

```
<PRE>
                               POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that the undersigned hereby constitutes and
appoints each of Kimberly Brown and Kenneth O'Brien the true and lawful
attorney-in-fact and agent, with full power of substitution and resubstitution,
for the undersigned and in the undersigned's name, place and stead, in any and
all capacities (until revoked in writing) to execute for and on behalf of the
undersigned, in any and all of the undersigned's capacities, any and all
statements on Forms 3, 4 and 5 with respect to the undersigned's holdings of and
transactions in securities issued by Repligen Corporation (the "Company") in
accordance with Sections 16(a) of the Securities Exchange Act of 1934, as
amended (the "Exchange Act"), and any and all regulations promulgated
thereunder, and to file the same, with all exhibits thereto, and any other
documents in connection therewith, with the Securities and Exchange Commission,
and with any other entity when and if such is mandated by the Exchange Act or by
the Bylaws of the Financial Industry Regulatory Authority, granting unto said
attorney-in-fact and agent full power and authority to do and perform each and
every act and thing requisite and necessary fully to all intents and purposes as
the undersigned might or could do in person thereby ratifying and confirming all
that said attorney-in-fact and agent, or his substitute or substitutes, may
lawfully do or cause to be done by virtue hereof.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorney-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of January 18, 2023.

                                     /s/ Martin D. Madaus
                                     ---------------------------
                                     Name: Martin D. Madaus

</PRE>
```

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

## FORM 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Madaus Martin D<br><sub>(Last) (First) (Middle)</sub><br>C/O REPLIGEN CORPORATION<br>41 SEYON ST., BLDG 1, STE 100<br><sub>(Street)</sub><br>WALTHAM, MA 02453<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>REPLIGEN CORP [ RGEN ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2023-02-06 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[X] Director   [ ] 10% Owner<br>[ ] Officer (give title below)   [ ] Other (specify below)<br>_ _ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |

---

**Remarks:**
Exhibit 24.1: Power of Attorney

**Signature:** /s/ Martin D. Madaus  
**Date:** 2023-02-08

### Remarks:

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.**