As of November 6, 2026, 4 holders' latest Schedule 13D or 13G filings report owning 5% or more of Cambridge Acquisition Corp. The largest reported stake is Cam-Phung Michael Tam's, at 29.19%. 6 filings are on record since February 12, 2026 (Schedule 13D, February 13, 2026).
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Key facts
- · Reporting person: Healthcare of Ontario Pension Plan Trust Fund · Sole voting: 1,100,000 · Shared voting: 0 · Sole dispositive: 1,100,000 · Shared dispositive: 0 · SCHEDULE 13G, 2026-08-13
- · Holder: Tenor Capital Management Company, L.P. · Percent: 4.3% · SCHEDULE 13G/A
- · Holder: Adage Capital Management, L.P. · Percent: 7.66% · SCHEDULE 13G
- · Holder: Magnetar Financial LLC · Percent: 7.23% · SCHEDULE 13G
- · Holder: Cam-Phung Michael Tam · Percent: 29.19% · SCHEDULE 13D
Cambridge Acquisition Corp. has 6 Schedule 13D or 13G filings on record since 2026-02-12. 4 holders' latest filing reports 5% or more of class a ordinary shares, $0.0001 par value. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| 29.19% | 8,162,167 | SCHEDULE 13D, 2026-02-13 | 2026-02-09 | |
| Adage Capital Management, L.P. | 7.66% | 1,800,000 | SCHEDULE 13G, 2026-05-13 | 2026-03-31 |
| Magnetar Financial LLC | 7.23% | 1,700,000 | SCHEDULE 13G, 2026-05-13 | 2026-03-31 |
| Healthcare of Ontario Pension Plan Trust Fund | 6.3% | 1,100,000 | SCHEDULE 13G, 2026-08-13 | 2026-06-30 |
| Tenor Capital Management Company, L.P. | 4.3% | 1,000,000 | SCHEDULE 13G/A, 2026-05-15 | 2026-03-31 |
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More on Cambridge Acquisition Corp. and the records around it.
Companies that share a holder
- Healthcare of Ontario Pension Plan Trust Fund also filed stake reports on 27 other companies: General Purpose Acquisition Corp. (May 2026), Artius II Acquisition Inc. (Feb 2026), Better Home & Finance Holding Company (Feb 2026)
- Tenor Capital Management Company, L.P. also filed stake reports on 41 other companies: Archimedes Tech SPAC Partners II Co. (Aug 2026), Armada Acquisition Corp. II (Aug 2026), Blue Acquisition Corp. (Aug 2026)
- MAGNETAR FINANCIAL LLC also filed stake reports on 97 other companies: Blue Acquisition Corp. (Sep 2026), CENTURION ACQUISITION CORP. (Sep 2026), Churchill Capital Corp IX (Sep 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Healthcare of Ontario Pension Plan Trust Fund | 1,100,000 | 0 | 1,100,000 | 0 | SCHEDULE 13G, 2026-08-13 |
The latest filing identifies Cambridge Acquisition Corp. by CUSIP G1871M108 and gives its principal executive office as One Liberty Square, 13th FL, Boston, MA 02109 (SCHEDULE 13G, 2026-08-13).
Purpose of Transaction (Item 4)
Cam-Phung Michael Tam
In connection with the organization of the Issuer, on October 30, 2025, 7,666,667 Class B Ordinary Shares (the "Founder Shares") were purchased by the Sponsor for the amount of $25,000, pursuant to a Securities Subscription Agreement, dated as of October 30, 2025, by and between the Sponsor and the Issuer (the "Subscription Agreement"), as more fully described in Item 6 of this Schedule 13D which information is incorporated herein by reference. On February 9, 2026, simultaneously with the consummation of the Issuer's Initial Public Offering (the "IPO"), the Sponsor purchased 495,500 units ("Placement Units") of the Issuer at $10.00 per Placement Unit, pursuant to a Private Placement Units Purchase Agreement, dated as of February 5, 2026, by and between the Issuer and the Sponsor (the "Placement Units Purchase Agreement"), as more fully described in Item 6 of this Schedule 13D, which information is incorporated herein by reference. Each Placement Unit consists of one Class A Ordinary Share and one-third of a warrant, with each whole warrant exercisable into one Class A ordinary share at an exercise price of $11.50, subject to adjustment, commencing 30 days following the consummation of the Issuer's initial business combination (as described more fully in the Issuer's Final Prospectus dated February 5, 2026). The Ordinary Shares owned by the Reporting Persons have been acquired for investment purposes. The Reporting Persons may make further acquisitions of the Ordinary Shares …The first part of Item 4 of the SCHEDULE 13D filed 2026-02-13; the filing has the rest
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2026-02-12 | Tenor Capital Management Company, L.P. | 5.9% | SCHEDULE 13G |
| 2026-02-13 | Cam-Phung Michael Tam | 29.19% | SCHEDULE 13D |
| 2026-05-13 | Adage Capital Management, L.P. | 7.66% | SCHEDULE 13G |
| 2026-05-13 | Magnetar Financial LLC | 7.23% | SCHEDULE 13G |
| 2026-05-15 | Tenor Capital Management Company, L.P. | 4.3% | SCHEDULE 13G/A |
| 2026-08-13 | Healthcare of Ontario Pension Plan Trust Fund | 6.3% | SCHEDULE 13G |
Questions about who owns Cambridge Acquisition Corp.
Who owns Cambridge Acquisition Corp.?
On this page, 4 holders' latest ownership filings report 5% or more of Cambridge Acquisition Corp.: Cam-Phung Michael Tam (29.19%, Schedule 13D, filed 2026-02-13), Adage Capital Management, L.P. (7.66%, Schedule 13G, filed 2026-05-13), Magnetar Financial LLC (7.23%, Schedule 13G, filed 2026-05-13) and Healthcare of Ontario Pension Plan Trust Fund (6.3%, Schedule 13G, filed 2026-08-13).
Who are the largest shareholders of Cambridge Acquisition Corp.?
By the share each holder's latest filing reports, the largest holders of Cambridge Acquisition Corp. on this page are Cam-Phung Michael Tam (29.19%), Adage Capital Management, L.P. (7.66%) and Magnetar Financial LLC (7.23%).
When did Cam-Phung Michael Tam buy into Cambridge Acquisition Corp.?
The filings give report dates, not purchase dates. The earliest filing from Cam-Phung Michael Tam on this page is the Schedule 13D, filed 2026-02-13, reporting 29.19%.
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%); 6 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 Cambridge Acquisition Corp.
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| February 6, 2026 | IPO filing, Form 424B4 | — | IPO filings | Source |
| January 30, 2026 | IPO filing, Form S-1/A | — | IPO filings | Source |
| December 15, 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.