# EDGAR Filing Document

**Accession Number:** 0001432602
**File Stem:** 0001829126-26-002587
**Filing Date:** 2026-3
**Character Count:** 7994
**Document Hash:** 02fe929ac036565eaa285ab201d1dfac
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001829126-26-002587.hdr.sgml**: 20260320

**ACCESSION NUMBER**: 0001829126-26-002587

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260319

**FILED AS OF DATE**: 20260320

**DATE AS OF CHANGE**: 20260320

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** You Harry L.
- **CENTRAL INDEX KEY:** 0001432602

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43203
- **FILM NUMBER:** 26778709

**MAIL ADDRESS:**
- **STREET 1:** 3421 HILLVIEW AVENUE
- **CITY:** PALO ALTO
- **STATE:** CA
- **ZIP:** 94304
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Horizon Quantum Holdings Ltd.
- **CENTRAL INDEX KEY:** 0002088256
- **STANDARD INDUSTRIAL CLASSIFICATION:** SERVICES-COMPUTER PROGRAMMING SERVICES [7371]
- **ORGANIZATION NAME:** 06 Technology
- **EIN:** 000000000
- **STATE OF INCORPORATION:** U0
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** ALICE@MEDIAOPOLIS
- **STREET 2:** 29 MEDIA CIRCLE #05-22
- **CITY:** SINGAPORE
- **PROVINCE COUNTRY:** U0
- **ZIP:** 138565
- **BUSINESS PHONE:** 6581015024

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** ALICE@MEDIAOPOLIS
- **STREET 2:** 29 MEDIA CIRCLE #05-22
- **CITY:** SINGAPORE
- **PROVINCE COUNTRY:** U0
- **ZIP:** 138565

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Horizon Quantum Holdings Pte. Ltd.
- **DATE OF NAME CHANGE:** 20251230

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Rose Holdco Pte. Ltd.
- **DATE OF NAME CHANGE:** 20250924

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>You Harry L.<br><sub>(Last) (First) (Middle)</sub><br>1180 NORTH TOWN CENTER DR, SUITE 100<br><sub>(Street)</sub><br>LAS VEGAS, NV 89144<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-03-19 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[X] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Horizon Quantum Holdings Ltd. [ HQ ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Class A Ordinary Shares | 2026-03-19 |  | A |  | 1163484 | A | <sup>(1)</sup> | 1163484 | I | See footnote<sup>(3)</sup> |
| Class A Ordinary Shares |  |  |  |  |  |  |  | 49214 | D |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Warrants | $11.50 | 2026-03-19 |  | A |  | 2884660 |  | 2026-04-18 | 2031-03-19 | Class A Ordinary Shares | 2884660 | <sup>(2)</sup> | 2884660 | I | See footnote<sup>(3)</sup> |

---

### Footnotes:

(1) In connection with the closing of the business combination (the "Business Combination") among Horizon Quantum Holdings Ltd. (the "Issuer"), Horizon Quantum Computing Pte. Ltd. ("Horizon"), and dMY Squared Technology Group, Inc. ("DMY"), these Class A ordinary shares of the Issuer were issued pursuant to the terms of the Business Combination Agreement, dated as of September 9, 2025, by and among the Issuer, Horizon, and DMY (the "Business Combination Agreement") upon the exchange of 1,163,484 shares of Class A common stock of DMY. On the effective date of the Business Combination, the closing price of DMY's Class A common stock was $13.50.

(2) In connection with the closing of the Business Combination, these warrants of the Issuer were issued pursuant to the terms of the Business Combination Agreement upon the exchange of 2,884,660 warrants of DMY. On the effective date of the Business Combination, the closing price of DMY's warrants was $2.69.

(3) dMY Squared Sponsor, LLC (the "Sponsor") Sponsor is the record holder of the securities reported herein. Harry L. You is the managing member of the Sponsor and has voting and investment discretion with respect to the securities held of record by the Sponsor. Each of the Sponsor and Mr. You is a "Reporting Person" and may be deemed to beneficially own the securities reported herein; however, each Reporting Person disclaims beneficial ownership of the securities reported herein, except to the extent of such Reporting Person's pecuniary interest therein. Solely for purposes of Section 16 of the Exchange Act, each Reporting Person may be deemed a "director by deputization".

**Remarks:**
Due to the Issuer's status as a foreign private issuer pursuant to Rule 3a12-3(b) under the Act, the Reporting Person's transactions in the Issuer's equity securities are exempt from Sections 16(b) and 16(c) of the Act.

**Signature:** /s/ Harry L. You  
**Date:** 2026-03-20

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**