# EDGAR Filing Document

**Accession Number:** 0001906837
**File Stem:** 0001062993-25-013461
**Filing Date:** 2025-8
**Character Count:** 11879
**Document Hash:** a745b28ef63b619d1f7e7c768c2148e9
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001062993-25-013461.hdr.sgml**: 20250801

**ACCESSION NUMBER**: 0001062993-25-013461

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20250801

**FILED AS OF DATE**: 20250801

**DATE AS OF CHANGE**: 20250801

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** ARCH Venture Fund XII, L.P.
- **CENTRAL INDEX KEY:** 0001906837

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-41536
- **FILM NUMBER:** 251177663

**BUSINESS ADDRESS:**
- **STREET 1:** 8755 W. HIGGINS ROAD, SUITE 1025
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60631
- **BUSINESS PHONE:** 773-380-6600

**MAIL ADDRESS:**
- **STREET 1:** 8755 W. HIGGINS ROAD, SUITE 1025
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60631
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** ARCH Venture Partners XII, L.P.
- **CENTRAL INDEX KEY:** 0001979765

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-41536
- **FILM NUMBER:** 251177664

**BUSINESS ADDRESS:**
- **STREET 1:** 8755 W HIGGINS ROAD
- **STREET 2:** SUITE 1025
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60631
- **BUSINESS PHONE:** 7733806600

**MAIL ADDRESS:**
- **STREET 1:** 8755 W HIGGINS ROAD
- **STREET 2:** SUITE 1025
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60631
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** ARCH Venture Partners XII, LLC
- **CENTRAL INDEX KEY:** 0001979548

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-41536
- **FILM NUMBER:** 251177665

**BUSINESS ADDRESS:**
- **STREET 1:** 8755 W HIGGINS ROAD
- **STREET 2:** SUITE 1025
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60631
- **BUSINESS PHONE:** 7733806600

**MAIL ADDRESS:**
- **STREET 1:** 8755 W HIGGINS ROAD
- **STREET 2:** SUITE 1025
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60631
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Prime Medicine, Inc.
- **CENTRAL INDEX KEY:** 0001894562
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 60 FIRST ST.
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02141
- **BUSINESS PHONE:** 617-465-0013

**MAIL ADDRESS:**
- **STREET 1:** 60 FIRST ST.
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02141

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

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] 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**<sup>*</sup><br>ARCH Venture Partners XII, LLC<br><sub>(Last) (First) (Middle)</sub><br>8755 W. HIGGINS ROAD, SUITE 1025<br><sub>(Street)</sub><br>CHICAGO, IL 60631<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-08-01 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Prime Medicine, Inc. [ PRME ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>ARCH Venture Partners XII, L.P.<br><sub>(Last) (First) (Middle)</sub><br>8755 W. HIGGINS ROAD, SUITE 1025<br><sub>(Street)</sub><br>CHICAGO, IL 60631<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-08-01 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Prime Medicine, Inc. [ PRME ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>ARCH Venture Fund XII, L.P.<br><sub>(Last) (First) (Middle)</sub><br>8755 W. HIGGINS ROAD, SUITE 1025<br><sub>(Street)</sub><br>CHICAGO, IL 60631<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-08-01 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Prime Medicine, Inc. [ PRME ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock |  |  |  |  |  |  |  | 6128297 | I | By ARCH Venture Fund X, L.P.<sup>(1)(3)</sup> |
| Common Stock |  |  |  |  |  |  |  | 6128297 | I | By ARCH Venture Fund X Overage, L.P.<sup>(2)(3)</sup> |
| Common Stock | 2025-08-01 |  | P |  | 3030300 | A | $3.30 | 6230300 | I | By ARCH Venture Fund XII, L.P.<sup>(4)</sup> |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

---

### Footnotes:

(1) Represents shares held directly by ARCH Venture Fund X, L.P. ("ARCH X"). ARCH Venture Partners X, L.P. ("AVP X LP") is the sole general partner of ARCH X.

(2) Represents shares held directly by ARCH Venture Fund X Overage, L.P. ("ARCH X Overage"). ARCH Venture Partners X Overage, L.P. ("AVP X Overage LP") is the sole general partner of ARCH X Overage.

(3) ARCH Venture Partners X, LLC ("AVP X LLC") is the sole general partner of each of AVP X LP and AVP X Overage LP. Keith Crandell, Kristina Burow and Steven Gillis are members of the investment committee of AVP X LLC (the "AVP X Committee Members"). AVP X LP and AVP X Overage LP may be deemed to beneficially own the shares held by ARCH X and ARCH X Overage, respectively, AVP X LLC may be deemed to beneficially own the shares held by ARCH X and ARCH X Overage, and each of the AVP X Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH X and ARCH X Overage. AVP X LP, AVP X Overage LP, AVP X LLC, and the AVP X Committee Members each disclaim beneficial ownership except to the extent of any pecuniary interest therein, and this report shall not be deemed an admission that such shares are beneficially owned by them for Section 16 or any other purpose.

(4) Represents shares held directly by ARCH Venture Fund XII, L.P. ("ARCH XII"). ARCH Venture Partners XII, L.P. ("AVP XII LP") is the general partner of ARCH XII. ARCH Venture Partners XII, LLC ("AVP XII LLC") is the general partner of AVP XII LP.  Keith Crandell, Kristina Burow and Steven Gillis are members of the investment committee of AVP XII LLC (the "AVP XII LLC Committee Members"). Each of AVP XII LP and AVP XII LLC may be deemed to beneficially own the shares held by ARCH XII, and each of the AVP XII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XII. Each of AVP XII LP, AVP XII LLC and the AVP XII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any.

**Remarks:**
This Form 4 is one of two reports relating to the same transaction being filed jointly by ARCH X, AVP X LP, ARCH X Overage, AVP X Overage LP, AVP X LLC, ARCH XII, AVP XII LP, AVP XII LLC, Keith Crandell, Kristina Burow and Steven Gillis (collectively, the "Reporting Persons"). Robert Nelsen has direct ownership of Common Stock and is filing his own Form 4 separately.

**Signature:** /s/ ARCH Venture Fund XII, L.P., By: ARCH Venture Partners XII, L.P., its General Partner, By: ARCH Venture Partners XII, LLC, its General Partner, By: Mark McDonnell, attorney-in-fact  
**Date:** 2025-08-01

**Signature:** /s/ ARCH Venture Partners XII, L.P., By: ARCH Venture Partners XII, LLC, its General Partner, By: Mark McDonnell, attorney-in-fact  
**Date:** 2025-08-01

**Signature:** /s/ ARCH Venture Fund XII, LLC, By: Mark McDonnell, attorney-in-fact  
**Date:** 2025-08-01

### 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.**