ARCH Venture Partners X, LLC - 01 Aug 2025 Form 4 Insider Report for Prime Medicine, Inc. (PRME)

Reporting relationship: 10%+ Owner
Issuer ticker: PRME
Reported as of: 01 Aug 2025
Net transaction value: +$9,999,990
SEC form: 4
Accepted by SEC: 01 Aug 2025, 19:18:42 UTC
Prior SEC filing: 30 Jan 2025
Next SEC filing: 29 Oct 2025
Source filing: View source filing
Reporting owner signature: /s/ ARCH Venture Fund X, L.P., By: ARCH Venture Partners X, L.P., its General Partner, By: ARCH Venture Partners X, LLC, its General Partner, By: Mark McDonnell, attorney-in-fact

Key filing fact

ARCH Venture Partners X, LLC filed Form 4 for Prime Medicine, Inc. (PRME) on 01 Aug 2025.

Key facts

This page summarizes ARCH Venture Partners X, LLC's Form 4 filing for Prime Medicine, Inc. (PRME).
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 01 Aug 2025, 19:18.

Change

Previous filing in this sequence was filed on 30 Jan 2025.
Current net transaction value: +$9,999,990.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (8)

CIK 0001769012 Primary reporting owner

ARCH Venture Partners X, LLC

Relationship: 10%+ Owner
Address: 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
Signature: /s/ ARCH Venture Fund X, L.P., By: ARCH Venture Partners X, L.P., its General Partner, By: ARCH Venture Partners X, LLC, its General Partner, By: Mark McDonnell, attorney-in-fact
Signature date: 01 Aug 2025

CIK 0001782583

ARCH Venture Partners X, L.P.

Relationship: 10%+ Owner
Address: 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
Signature: /s/ ARCH Venture Fund X Overage, L.P., By: ARCH Venture Partners X Overage, L.P., its General Partner, By: ARCH Venture Partners X, LLC, its General Partner, By: Mark McDonnell, attorney-in-fact
Signature date: 01 Aug 2025

CIK 0001768905

ARCH Venture Partners X Overage, L.P.

Relationship: 10%+ Owner
Address: 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
Signature: /s/ ARCH Venture Partners X, L.P., By: ARCH Venture Partners X, LLC, its General Partner, By: Mark McDonnell, attorney-in-fact
Signature date: 01 Aug 2025

CIK 0001757011

ARCH Venture Fund X, L.P.

Relationship: 10%+ Owner
Address: 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
Signature: /s/ ARCH Venture Partners X Overage, L.P., By: ARCH Venture Partners X, LLC, its General Partner, By: Mark McDonnell, attorney-in-fact
Signature date: 01 Aug 2025

CIK 0001757017

ARCH Venture Fund X Overage, L.P.

Relationship: 10%+ Owner
Address: 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
Signature: /s/ ARCH Venture Partners X, LLC, By: Mark McDonnell, attorney-in-fact
Signature date: 01 Aug 2025

CIK 0001219039

CRANDELL KEITH

Relationship: 10%+ Owner
Address: C/O ARCH VENTURE PARTNERS IX, LLC, 8755 W. HIGGINS ROAD, SUITE 1025, CHICAGO
Signature: /s/ Keith Crandell, By: Mark McDonnell, attorney-in-fact
Signature date: 01 Aug 2025

CIK 0001569248

Burow Kristina

Relationship: 10%+ Owner
Address: 8755 W. HIGGINS ROAD,SUITE 1025, CHICAGO
Signature: /s/ Kristina Burow, By: Mark McDonnell, attorney-in-fact
Signature date: 01 Aug 2025

CIK 0001229592

GILLIS STEVEN

Relationship: 10%+ Owner
Address: C/O ARCH VENTURE PARTNERS, 8755 WEST HIGGINS ROAD, SUITE 1025, CHICAGO
Signature: /s/ Steven Gillis, By: Mark McDonnell, attorney-in-fact
Signature date: 01 Aug 2025

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

PRME transaction

Common Stock

Purchase

Transaction value: $9,999,990
Shares: +3,030,300
Change %: +95%
Price: $3.30
Shares after: 6,230,300
Date: 01 Aug 2025
Ownership: By ARCH Venture Fund XII, L.P.
Footnotes: F4

PRME holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 6,128,297
Date: 01 Aug 2025
Ownership: By ARCH Venture Fund X, L.P.
Footnotes: F1, F3

PRME holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 6,128,297
Date: 01 Aug 2025
Ownership: By ARCH Venture Fund X Overage, L.P.
Footnotes: F2, F3

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 4 footnotes

Footnote F1

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.

Footnote F2

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.

Footnote F3

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.

Footnote F4

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.

SEC 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.