As of November 9, 2026, 5 holders' latest Schedule 13D or 13G filings report owning 5% or more of Horizon Quantum Holdings Ltd. The largest reported stake is Joseph Francis Fitzsimons', at 38.3%. 8 filings are on record since March 20, 2026 (Schedule 13D, March 31, 2026).
Who owns Horizon Quantum Holdings Ltd.?
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Key facts
- · Reporting person: Harry L. You · Sole voting: 2,655,028 · Shared voting: 0 · Sole dispositive: 2,655,028 · Shared dispositive: 0 · SCHEDULE 13D/A, 2026-11-05
- · Reporting person: Tencent Holdings Ltd · Sole voting: 3,800,438 · Shared voting: 0 · Sole dispositive: 3,800,438 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-08-14
- · Reporting person: Peak XV Partners Seed Investment · Sole voting: 0 · Shared voting: 6,468,999 · Sole dispositive: 0 · Shared dispositive: 6,468,999 · SCHEDULE 13D, 2026-07-09
- · Reporting person: ICS Opportunities, Ltd. · Sole voting: 0 · Shared voting: 17,500 · Sole dispositive: 0 · Shared dispositive: 17,500 · SCHEDULE 13G, 2026-06-25
- · Holder: IonQ, Inc. · Percent: 13.3% · SCHEDULE 13D
Horizon Quantum Holdings Ltd. has 8 Schedule 13D or 13G filings on record since 2026-03-20. 5 holders' latest filing reports 5% or more of class a ordinary shares. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| 38.3% | 19,744,585 | SCHEDULE 13D, 2026-03-31 | 2026-03-19 | |
| Peak XV Partners Seed Investment | 20.3% | 6,468,999 | SCHEDULE 13D, 2026-07-09 | 2026-03-19 |
| IonQ, Inc. | 13.3% | 4,230,118 | SCHEDULE 13D, 2026-04-01 | 2026-03-19 |
| Tencent Holdings Ltd | 11.1% | 3,800,438 | SCHEDULE 13G/A, 2026-08-14 | 2026-06-30 |
| 7.4% | 2,655,028 | SCHEDULE 13D/A, 2026-11-05 | 2026-11-03 | |
| ICS Opportunities, Ltd. | 0.1% | 17,500 | SCHEDULE 13G, 2026-06-25 | 2026-06-17 |
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More on Horizon Quantum Holdings Ltd. and the records around it.
Horizon Quantum Holdings Ltd. elsewhere on the record
Companies that share a holder
- Harry L. You also filed stake reports on 1 other company: Rain Enhancement Technologies Holdco, Inc. (Jun 2026)
- ICS Opportunities, Ltd. also filed stake reports on 2 other companies: Arqit Quantum Inc. (Jun 2026)
- Tencent Holdings Ltd also filed stake reports on 7 other companies: Amer Sports, Inc. (Aug 2026), Kanzhun Ltd (May 2026), Reddit, Inc. (Nov 2025)
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What the Full Report on Horizon Quantum Holdings Ltd. covers
The Short Answer
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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 |
|---|---|---|---|---|---|
| Peak XV Partners Seed Investment | 0 | 6,468,999 | 0 | 6,468,999 | SCHEDULE 13D, 2026-07-09 |
| Peak XV Partners Seed Fund I Ltd | 0 | 6,468,999 | 0 | 6,468,999 | SCHEDULE 13D, 2026-07-09 |
| Peak XV Partners Principals Seed Fund I Ltd | 0 | 6,468,999 | 0 | 6,468,999 | SCHEDULE 13D, 2026-07-09 |
| Peak XV Partners Seed Management I Ltd | 0 | 6,468,999 | 0 | 6,468,999 | SCHEDULE 13D, 2026-07-09 |
| Tencent Holdings Ltd | 3,800,438 | 0 | 3,800,438 | 0 | SCHEDULE 13G/A, 2026-08-14 |
| THL A12 Limited | 3,800,438 | 0 | 3,800,438 | 0 | SCHEDULE 13G/A, 2026-08-14 |
| Harry L. You | 2,655,028 | 0 | 2,655,028 | 0 | SCHEDULE 13D/A, 2026-11-05 |
| dMY Squared Sponsor, LLC | 0 | 0 | 0 | 0 | SCHEDULE 13D/A, 2026-11-05 |
| ICS Opportunities, Ltd. | 0 | 17,500 | 0 | 17,500 | SCHEDULE 13G, 2026-06-25 |
| Millennium Management LLC | 0 | 20,632 | 0 | 20,632 | SCHEDULE 13G, 2026-06-25 |
| Millennium Group Management LLC | 0 | 20,632 | 0 | 20,632 | SCHEDULE 13G, 2026-06-25 |
| Israel A. Englander | 0 | 20,632 | 0 | 20,632 | SCHEDULE 13G, 2026-06-25 |
The latest filing identifies Horizon Quantum Holdings Ltd. by CUSIP Y4000A102 and gives its principal executive office as 29 Media Cir. #05-22, Singapore (SCHEDULE 13D/A, 2026-11-05).
What the percentages are based on
See row 11 of the cover page of each reporting person. The foregoing calculation is based on an aggregate of 34,227,495 Class A Ordinary Shares outstanding as of June 30, 2026, as reported in the unaudited condensed consolidated interim financial statements of the Issuer filed as Exhibit 99.1 to the Issuer's current report on Form 6-K furnished to the U.S. Securities and Exchange Commission on August 4, 2026.Tencent Holdings Ltd, SCHEDULE 13G/A, 2026-08-14
Source of funds (Item 3)
Between March 25, 2020 and July 23, 2025, Peak Investments Seed acquired securities of Horizon Quantum Computing Pte. Ltd. (Company Registration No.: 201802755E), a Singapore private company limited by shares ("Private Horizon") for an aggregate investment of $6,000,000. Effective March 16, 2026 (the "Closing Date"), pursuant to the business combination agreement, dated as of September 9, 2025 (the "Business Combination Agreement") by and among the Issuer, dMY Squared Technology Group, Inc., Rose Acquisition Pte. Ltd.Peak XV Partners Seed Investment, SCHEDULE 13D, 2026-07-09
To the extent required by Item 3, the information contained in Item 4 is incorporated herein by reference.Harry L. You, SCHEDULE 13D/A, 2026-11-05
Purpose of Transaction (Item 4)
Harry L. You
Item 4 of Schedule 13D is hereby amended and supplemented by adding the following: On November 3, 2026, the Sponsor made a pro rata in-kind distribution of 1,163,484 Class A Ordinary Shares and 2,844,660 Warrants to its members for no consideration. Harry L. You, the managing member of the Sponsor, received 1,163,484 of such Class A Ordinary Shares and 1,442,330 of such Warrants in such pro rata in-kind distribution, and now holds such securities directly.Item 4 of the SCHEDULE 13D/A filed 2026-11-05
Joseph Francis Fitzsimons
As previously disclosed on the Issuer's Form 20-F filed with the Securities and Exchange Commission on filed on March 25, 2026,, on September 9, 2025, the Issuer entered into a Business Combination Agreement (the "Business Combination Agreement") with Horizon Quantum Computing Pte. Ltd. ("Horizon"), dMY Squared Technology Group, Inc. ("DMY"), Rose Acquisition Pte. Ltd. ("Merger Sub 1"), and Horizon Merger Sub 2, Inc. ("Merger Sub 2"), pursuant to which, and subject to the satisfaction or waiver of certain conditions set forth therein, on March 19, 2026, the following occurred: (1) the Issuer converted from a Singapore private company limited by shares to a Singapore public company limited by shares and, in connection therewith, adopted an amended and restated constitution (the "Holdco A&R Constitution"); (2) Merger Sub 1 amalgamated with Horizon, with Horizon surviving as the amalgamated company and a wholly-owned subsidiary of the Issuer (the "Amalgamation"); (3) Merger Sub 2 merged with and into DMY, with DMY surviving the merger as a wholly-owned subsidiary of the Issuer (the "SPAC Merger"); and (4) completion of the other transactions contemplated by the Business Combination Agreement and documents related thereto (such transactions, together with the Amalgamation and the SPAC Merger, the "Business Combination"). Prior to the Business Combination, Dr. Fitzsimons was the Chief Executive Officer, Chairman and a shareholder of Horizon. Immediately prior to the Business …The first part of Item 4 of the SCHEDULE 13D filed 2026-03-31; the filing has the rest
IonQ, Inc.
The information set forth in Item 3 and Item 6 is incorporated by reference in its entirety into this Item 4. The Reporting Person acquired the reported securities for investment purposes. Subject to the terms of, including the rights and obligations contained in, the Subscription Agreement and the Side Letter, as further described in Item 6, the Reporting Person intends to review its investment in the Issuer on a continuing basis. Depending on various factors, including, without limitation, the Issuer's financial position and strategic direction, actions taken by the Board of Directors of the Issuer (the "Issuer Board"), current and anticipated future price levels of the Issuer's securities, the relative attractiveness of alternative business and investment opportunities and other general economic and market conditions, the Reporting Person may in the future take such actions with respect to its investment as it considers appropriate, which may include, without limitation: - communicating with the Issuer's management and the Issuer Board, including any member thereof and other securityholders of the Issuer and other relevant parties; - exercising the Reporting Person's right under the Side Letter to designate a member of the Issuer Board; - acquiring additional securities of the Issuer (which may include rights or securities exercisable or convertible into securities of the Issuer) or disposing of some or all such securities then owned by the Reporting Person from time …The first part of Item 4 of the SCHEDULE 13D filed 2026-04-01; the filing has the rest
Peak XV Partners Seed Investment
Peak Investments Seed purchased the aforementioned securities for investment purposes with the aim of increasing the value of its investments and the Issuer. Subject to applicable legal requirements, one or more of the Reporting Persons may purchase additional securities of the Issuer from time to time in open market or private transactions, depending on its evaluation of the Issuer's business, prospects and financial condition, the market for the Issuer's securities, other developments concerning the Issuer, the reaction of the Issuer to the Reporting Persons' ownership of the Issuer's securities, other opportunities available to the Reporting Persons, and general economic, money market and stock market conditions. In addition, depending upon the factors referred to above, the Reporting Persons may dispose of all or a portion of their securities of the Issuer at any time (including by means of programs adopted pursuant to Rule 10b5-1 under the Act). Each of the Reporting Persons reserves the right to increase or decrease its holdings on such terms and at such times as each may decide. Except as set forth in this Item 4 and Item 6 below, none of the Reporting Persons has a present plan or proposal that relates to or would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D of the Act. However, each of the Reporting Persons reserves the right to propose or participate in future transactions which may result in one or more of such …The first part of Item 4 of the SCHEDULE 13D filed 2026-07-09; the filing has the rest
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2026-03-20 | Harry L. You | 11.8% | SCHEDULE 13D |
| 2026-03-25 | Tencent Holdings Ltd | 13.1% | SCHEDULE 13G |
| 2026-03-31 | Joseph Francis Fitzsimons | 38.3% | SCHEDULE 13D |
| 2026-04-01 | IonQ, Inc. | 13.3% | SCHEDULE 13D |
| 2026-06-25 | ICS Opportunities, Ltd. | 0.1% | SCHEDULE 13G |
| 2026-07-09 | Peak XV Partners Seed Investment | 20.3% | SCHEDULE 13D |
| 2026-08-14 | Tencent Holdings Ltd | 11.1% | SCHEDULE 13G/A |
| 2026-11-05 | Harry L. You | 7.4% | SCHEDULE 13D/A |
Questions about who owns Horizon Quantum Holdings Ltd.
Who owns Horizon Quantum Holdings Ltd.?
On this page, 5 holders' latest ownership filings report 5% or more of Horizon Quantum Holdings Ltd.: Joseph Francis Fitzsimons (38.3%, Schedule 13D, filed 2026-03-31), Peak XV Partners Seed Investment (20.3%, Schedule 13D, filed 2026-07-09), IonQ, Inc. (13.3%, Schedule 13D, filed 2026-04-01), Tencent Holdings Ltd (11.1%, Schedule 13G/A, filed 2026-08-14) and Harry L. You (7.4%, Schedule 13D/A, filed 2026-11-05).
Who are the largest shareholders of Horizon Quantum Holdings Ltd.?
By the share each holder's latest filing reports, the largest holders of Horizon Quantum Holdings Ltd. on this page are Joseph Francis Fitzsimons (38.3%), Peak XV Partners Seed Investment (20.3%) and IonQ, Inc. (13.3%).
When did Joseph Francis Fitzsimons buy into Horizon Quantum Holdings Ltd.?
The filings give report dates, not purchase dates. The earliest filing from Joseph Francis Fitzsimons on this page is the Schedule 13D, filed 2026-03-31, reporting 38.3%.
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.
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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.