As of November 6, 2026, 2 holders' latest Schedule 13D or 13G filings report owning 5% or more of Prime Medicine Inc. The largest reported stake is Alphabet Holdings LLC's, at 12.3%. 5 filings are on record since August 11, 2025 (Schedule 13G/A, November 12, 2025).
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Key facts
- · Reporting person: T. Rowe Price Investment Management, Inc. · Sole voting: 5,995,183 · Shared voting: 0 · Sole dispositive: 5,995,183 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-02-17
- · Holder: T. Rowe Price Investment Management, Inc. · Percent: 5.3% · SCHEDULE 13G
- · Reporting person: Gv 2019, L.P. · Sole voting: 0 · Shared voting: 10,100,058 · Sole dispositive: 0 · Shared dispositive: 10,100,058 · SCHEDULE 13G/A, 2025-11-12
- · Reporting person: Fmr LLC · Sole voting: 6,724,867 · Shared voting: 0 · Sole dispositive: 6,731,796 · Shared dispositive: 0 · SCHEDULE 13G/A, 2025-11-05
- · Holder: ARCH Venture Fund XII, L.P. · Percent: 10.4% · SCHEDULE 13D/A
Prime Medicine Inc has 5 Schedule 13D or 13G filings on record since 2025-08-11. 2 holders' latest filing reports 5% or more of common stock. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Alphabet Holdings LLC | 12.3% | 16,562,498 | SCHEDULE 13G/A, 2025-11-12 | 2025-09-30 |
| ARCH Venture Fund XII, L.P. | 10.4% | 18,486,894 | SCHEDULE 13D/A, 2025-08-11 | 2025-08-07 |
| Fmr LLC | 3.8% | 6,731,796 | SCHEDULE 13G/A, 2025-11-05 | 2025-09-30 |
| T. Rowe Price Investment Management, Inc. | 3.3% | 5,995,183 | SCHEDULE 13G/A, 2026-02-17 | 2025-12-31 |
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Keep reading
More on Prime Medicine Inc and the records around it.
Prime Medicine Inc elsewhere on the record
- Leadership changes Apr 2026
- Who owns it
Companies that share a holder
- GV 2019, L.P. also filed stake reports on 2 other companies: Ethos Technologies Inc. (Nov 2026), MAZE THERAPEUTICS, INC. (Feb 2026)
- ARCH Venture Fund X, L.P. also filed stake reports on 5 other companies: City Therapeutics, Inc. (Oct 2026), Parabilis Medicines, Inc. (Aug 2026), Seaport Therapeutics, Inc. (May 2026)
- T. Rowe Price Investment Management, Inc. also filed stake reports on 167 other companies: CABALETTA BIO INC (Nov 2026), MADISON SQUARE GARDEN SPORTS CORP (Nov 2026), MSG RANGERS CORP (Nov 2026)
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What the Full Report on Prime Medicine Inc covers
The Short Answer
Which Company This Is
What They Do, And How The Money Works
Who Runs It, And How To Reach Them
The Money: Funding, Valuation, Runway
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Gv 2019, L.P. | 0 | 10,100,058 | 0 | 10,100,058 | SCHEDULE 13G/A, 2025-11-12 |
| Gv 2019 Gp, L.P. | 0 | 10,100,058 | 0 | 10,100,058 | SCHEDULE 13G/A, 2025-11-12 |
| Gv 2019 Gp, L.L.C. | 0 | 10,100,058 | 0 | 10,100,058 | SCHEDULE 13G/A, 2025-11-12 |
| Gv 2021, L.P. | 0 | 3,262,440 | 0 | 3,262,440 | SCHEDULE 13G/A, 2025-11-12 |
| Gv 2021 Gp, L.P. | 0 | 3,262,440 | 0 | 3,262,440 | SCHEDULE 13G/A, 2025-11-12 |
| Gv 2021 Gp, L.L.C. | 0 | 3,262,440 | 0 | 3,262,440 | SCHEDULE 13G/A, 2025-11-12 |
| Gv 2023, L.P. | 0 | 3,200,000 | 0 | 3,200,000 | SCHEDULE 13G/A, 2025-11-12 |
| Gv 2023 Gp, L.P. | 0 | 3,200,000 | 0 | 3,200,000 | SCHEDULE 13G/A, 2025-11-12 |
| Gv 2023 Gp, L.L.C. | 0 | 3,200,000 | 0 | 3,200,000 | SCHEDULE 13G/A, 2025-11-12 |
| Alphabet Holdings LLC | 0 | 16,562,498 | 0 | 16,562,498 | SCHEDULE 13G/A, 2025-11-12 |
| XXVI Holdings Inc. | 0 | 16,562,498 | 0 | 16,562,498 | SCHEDULE 13G/A, 2025-11-12 |
| Alphabet Inc. | 0 | 16,562,498 | 0 | 16,562,498 | SCHEDULE 13G/A, 2025-11-12 |
| Fmr LLC | 6,724,867 | 0 | 6,731,796 | 0 | SCHEDULE 13G/A, 2025-11-05 |
| Abigail P. Johnson | 0 | 0 | 6,731,796 | 0 | SCHEDULE 13G/A, 2025-11-05 |
| T. Rowe Price Investment Management, Inc. | 5,995,183 | 0 | 5,995,183 | 0 | SCHEDULE 13G/A, 2026-02-17 |
The latest filing names Prime Medicine Inc, with its principal executive office as 60 FIRST ST., CAMBRIDGE, MA 2141 (SCHEDULE 13G/A, 2026-02-17).
What the percentages are based on
As of the Event Date, the Reporting Persons were deemed to directly or indirectly beneficially own an aggregate 12.3% of the Issuer's outstanding Common Stock.Alphabet Holdings LLC, SCHEDULE 13G/A, 2025-11-12
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-11 | ARCH Venture Fund XII, L.P. | 10.4% | SCHEDULE 13D/A |
| 2025-11-05 | Fmr LLC | 3.8% | SCHEDULE 13G/A |
| 2025-11-12 | Alphabet Holdings LLC | 12.3% | SCHEDULE 13G/A |
| 2025-11-14 | T. Rowe Price Investment Management, Inc. | 5.3% | SCHEDULE 13G |
| 2026-02-17 | T. Rowe Price Investment Management, Inc. | 3.3% | SCHEDULE 13G/A |
Questions about who owns Prime Medicine Inc
Who owns Prime Medicine Inc?
On this page, 2 holders' latest ownership filings report 5% or more of Prime Medicine Inc: Alphabet Holdings LLC (12.3%, Schedule 13G/A, filed 2025-11-12) and ARCH Venture Fund XII, L.P. (10.4%, Schedule 13D/A, filed 2025-08-11).
Who are the largest shareholders of Prime Medicine Inc?
By the share each holder's latest filing reports, the largest holders of Prime Medicine Inc on this page are Alphabet Holdings LLC (12.3%) and ARCH Venture Fund XII, L.P. (10.4%).
When did Alphabet Holdings LLC buy into Prime Medicine Inc?
The filings give report dates, not purchase dates. The earliest filing from Alphabet Holdings LLC on this page is the Schedule 13G/A, filed 2025-11-12, reporting 12.3%. That earliest filing is itself an amendment, which updates an earlier report.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 5 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
Also on the record for Prime Medicine Inc
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| April 16, 2026 | Leadership change: Svetlana Makhni appointed, Chief Financial Officer | — | Leadership changes | Source |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.