As of November 6, 2026, 3 holders' latest Schedule 13D or 13G filings report owning 5% or more of Perimeter Acquisition Corp I. The largest reported stake is Harraden Circle Investments, LLC's, at 9.85%. 8 filings are on record since August 8, 2025 (Schedule 13G/A, August 14, 2026).
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Key facts
- · Reporting person: Harraden Circle Investments, LLC · Sole voting: 0 · Shared voting: 2,440,298 · Sole dispositive: 0 · Shared dispositive: 2,440,298 · SCHEDULE 13G/A, 2026-08-14
- · Reporting person: Fort Baker Capital Management LP · Sole voting: 0 · Shared voting: 1,573,684 · Sole dispositive: 0 · Shared dispositive: 1,573,684 · SCHEDULE 13G, 2026-05-15
- · Reporting person: Healthcare of Ontario Pension Plan Trust Fund · Sole voting: 450,000 · Shared voting: 0 · Sole dispositive: 450,000 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-02-13
- · Holder: Harraden Circle Investments, LLC · Percent: 9.28% · SCHEDULE 13G/A
- · Holder: Healthcare of Ontario Pension Plan Trust Fund · Percent: 5% · SCHEDULE 13G/A
Perimeter Acquisition Corp I has 8 Schedule 13D or 13G filings on record since 2025-08-08. 3 holders' latest filing reports 5% or more of class a. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Harraden Circle Investments, LLC | 9.85% | 2,440,298 | SCHEDULE 13G/A, 2026-08-14 | 2026-06-30 |
| Fort Baker Capital Management LP | 6.3% | 1,573,684 | SCHEDULE 13G, 2026-05-15 | 2026-03-31 |
| Magnetar Financial LLC | 6.05% | 1,500,000 | SCHEDULE 13G, 2025-08-08 | 2025-06-30 |
| Healthcare of Ontario Pension Plan Trust Fund | 1.8% | 450,000 | SCHEDULE 13G/A, 2026-02-13 | 2025-12-31 |
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More on Perimeter Acquisition Corp I and the records around it.
Companies that share a holder
- Fort Baker Capital Management LP also filed stake reports on 26 other companies: Agriculture & Natural Solutions Acquisition Corp (Aug 2026), Bleichroeder Acquisition Corp. II (Aug 2026), Cartesian Growth Corp III (Aug 2026)
- Healthcare of Ontario Pension Plan Trust Fund also filed stake reports on 27 other companies: Cambridge Acquisition Corp. (Aug 2026), General Purpose Acquisition Corp. (May 2026), Artius II Acquisition Inc. (Feb 2026)
- Harraden Circle Investments, LLC also filed stake reports on 95 other companies: Calisa Acquisition Corp (Nov 2026), Texas Ventures Acquisition III Corp (Nov 2026), Columbus Acquisition Corp (Oct 2026)
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What the Full Report on Perimeter Acquisition Corp I covers
The Short Answer
Which Company This Is
What They Do, And How The Money Works
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Harraden Circle Investments, LLC | 0 | 2,440,298 | 0 | 2,440,298 | SCHEDULE 13G/A, 2026-08-14 |
| Frederick V. Fortmiller, Jr. | 0 | 2,440,298 | 0 | 2,440,298 | SCHEDULE 13G/A, 2026-08-14 |
| Fort Baker Capital Management LP | 0 | 1,573,684 | 0 | 1,573,684 | SCHEDULE 13G, 2026-05-15 |
| Steven Patrick Pigott | 0 | 1,573,684 | 0 | 1,573,684 | SCHEDULE 13G, 2026-05-15 |
| Fort Baker Capital, LLC | 0 | 1,573,684 | 0 | 1,573,684 | SCHEDULE 13G, 2026-05-15 |
| Healthcare of Ontario Pension Plan Trust Fund | 450,000 | 0 | 450,000 | 0 | SCHEDULE 13G/A, 2026-02-13 |
The latest filing identifies Perimeter Acquisition Corp I by CUSIP G7010A129 and gives its principal executive office as 12700 Hillcrest Rd, Suite 125, Dallas, TX 75230 (SCHEDULE 13G/A, 2026-08-14).
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-08 | Magnetar Financial LLC | 6.05% | SCHEDULE 13G |
| 2025-08-13 | Healthcare of Ontario Pension Plan Trust Fund | 6.1% | SCHEDULE 13G |
| 2025-08-14 | Harraden Circle Investments, LLC | 7.66% | SCHEDULE 13G/A |
| 2025-11-13 | Healthcare of Ontario Pension Plan Trust Fund | 5% | SCHEDULE 13G/A |
| 2026-02-13 | Healthcare of Ontario Pension Plan Trust Fund | 1.8% | SCHEDULE 13G/A |
| 2026-02-13 | Harraden Circle Investments, LLC | 9.28% | SCHEDULE 13G/A |
| 2026-05-15 | Fort Baker Capital Management LP | 6.3% | SCHEDULE 13G |
| 2026-08-14 | Harraden Circle Investments, LLC | 9.85% | SCHEDULE 13G/A |
Questions about who owns Perimeter Acquisition Corp I
Who owns Perimeter Acquisition Corp I?
On this page, 3 holders' latest ownership filings report 5% or more of Perimeter Acquisition Corp I: Harraden Circle Investments, LLC (9.85%, Schedule 13G/A, filed 2026-08-14), Fort Baker Capital Management LP (6.3%, Schedule 13G, filed 2026-05-15) and Magnetar Financial LLC (6.05%, Schedule 13G, filed 2025-08-08).
Who are the largest shareholders of Perimeter Acquisition Corp I?
By the share each holder's latest filing reports, the largest holders of Perimeter Acquisition Corp I on this page are Harraden Circle Investments, LLC (9.85%), Fort Baker Capital Management LP (6.3%) and Magnetar Financial LLC (6.05%).
When did Harraden Circle Investments, LLC buy into Perimeter Acquisition Corp I?
The filings give report dates, not purchase dates. The earliest filing from Harraden Circle Investments, LLC on this page is the Schedule 13G/A, filed 2025-08-14, reporting 7.66%; its latest, Schedule 13G/A filed 2026-08-14, reports 9.85%. 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%); 8 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 Perimeter Acquisition Corp I
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| May 14, 2025 | IPO filing, Form 424B4 | — | IPO filings | Source |
| May 7, 2025 | IPO filing, Form S-1/A | — | IPO filings | Source |
| April 18, 2025 | IPO filing, Form S-1/A | — | IPO filings | Source |
| March 20, 2025 | IPO filing, Form S-1 | — | IPO filings | 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.