Reported relationships
Latest disclosed role at each company.
| Company | Last reported as | Report date | Published |
|---|---|---|---|
| Horizon Quantum Holdings Ltd.HQ · Entity 5127 | Chief Science Officer | March 19, 2026 | September 16, 2026 |
Disclosed balances
About these balances
Latest available filing per company, not a reconstructed current portfolio. Matching sequences show the last reported balance with all source rows expandable; grouping alone does not establish account ownership. Do not add unresolved positions together. Filings may omit unchanged positions, and amendments may correct only part of an older disclosure. Jointly reported shares are not necessarily this owner's personal holdings.
Horizon Quantum Holdings Ltd.
Report date March 19, 2026 · Filed September 16, 2026
| Security / award | Ownership account | Disclosed shares / units | Disclosure context |
|---|---|---|---|
| Class A Ordinary SharesSEC Table I · non-derivative | IndirectBy Spouse | 3,600 |
Reported balance
After 2026-08-20 transaction · row 1
Account identity is unresolved; indirect or unspecified ownership is not merged.
1 source rowRow 1 · 2026-08-20 · Grant · Acquired 3,600 · Balance 3,600 F1: On August 20, 2026 (the "August Grant Date"), Dr. Tan's spouse was granted a total of unvested 3,600 RSUs. The RSUs granted to Dr. Tan's spouse are subject to his continued employment with the Company and vest in accordance with the following schedule: One quarter (1/4) of the total number of RSUs vest on the first anniversary of the August Grant Date with the remaining three quarters (3/4) vesting in twelve approximately equal quarterly installments on 20th day of each fiscal quarter. F2: Each restricted stock unit ("RSU") represents a contingent right to receive one Class A ordinary share, with no par value ("Class A Ordinary Share"), of Horizon Quantum Holdings Ltd. (the "Company") upon vesting, for no consideration. |
| Class A Ordinary SharesSEC Table I · non-derivative | Direct | 2,737 |
Ending reported balance
After 2026-09-12 transaction · row 3
2 source rows · reconciled sequenceRow 2 · 2026-09-12 · Exercise / conversion · Acquired 5,728 · Balance 5,728 F3: On September 12, 2026, 5,728 of Dr. Tan's RSU's vested. F4: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. Row 3 · 2026-09-12 · Disposition to issuer · Disposed 2,991 · Balance 2,737 F5: The reported disposition to the Company reflects the settlement in cash of a portion of the RSUs which vested on September 12, 2026, at a price per ordinary share of $15.22, the last reported sales price of the Company's Class A Ordinary Shares on September 11, 2026. |
| Stock Option (Right to Buy)SEC Table II · derivative / convertible security · Conversion / exercise price $2.88 · Expires 2035-02-01 | IndirectBy Spouse | 55,000 |
Reported balance
After 2026-03-19 transaction · row 4
Instrument identity requires review; Table II rows are not merged.
1 source rowRow 4 · 2026-03-19 · Grant · Acquired 55,000 · Balance 55,000 F6: Each stock option has an exercise price of $2.88 and is exercisable for approximately 2.43499 Class A Ordinary Shares of the Company. In aggregate, Dr. Tan's spouse's stock options, once fully vested, are exercisable for 133,924 Class A Ordinary Shares of the Company. F7: Of the 55,000 stock options, 37,811 stock options are currently fully vested and exercisable. The remaining stock options vest in five approximately equal quarterly installments beginning on November 20, 2026, subject to Dr. Tan's spouse's continued employment with the Company. F8: As a result of the closing of the Company's business combination on March 19, 2026, Dr. Tan's spouse's 55,000 Legacy Horizon stock options were exchanged for 55,000 stock options of the Company of an equivalent economic value, with an exercise price per Class A Ordinary Share of $2.88. |
| Restricted Stock UnitSEC Table II · derivative / convertible security · Conversion / exercise price $0.00 | Direct | 91,659 |
Reported balance
After 2026-06-12 transaction · row 5
Instrument identity requires review; Table II rows are not merged.
1 source rowRow 5 · 2026-06-12 · Grant · Acquired 91,659 · Balance 91,659 F2: Each restricted stock unit ("RSU") represents a contingent right to receive one Class A ordinary share, with no par value ("Class A Ordinary Share"), of Horizon Quantum Holdings Ltd. (the "Company") upon vesting, for no consideration. F4: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. |
| Restricted Stock UnitSEC Table II · derivative / convertible security · Conversion / exercise price $0.00 | Direct | 85,931 |
Reported balance
After 2026-09-12 transaction · row 6
Instrument identity requires review; Table II rows are not merged.
1 source rowRow 6 · 2026-09-12 · Exercise / conversion · Acquired 5,728 · Balance 85,931 F2: Each restricted stock unit ("RSU") represents a contingent right to receive one Class A ordinary share, with no par value ("Class A Ordinary Share"), of Horizon Quantum Holdings Ltd. (the "Company") upon vesting, for no consideration. F3: On September 12, 2026, 5,728 of Dr. Tan's RSU's vested. F4: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. |
Filing footnotes · ownership attribution and instrument terms
F1: On August 20, 2026 (the "August Grant Date"), Dr. Tan's spouse was granted a total of unvested 3,600 RSUs. The RSUs granted to Dr. Tan's spouse are subject to his continued employment with the Company and vest in accordance with the following schedule: One quarter (1/4) of the total number of RSUs vest on the first anniversary of the August Grant Date with the remaining three quarters (3/4) vesting in twelve approximately equal quarterly installments on 20th day of each fiscal quarter.
F2: Each restricted stock unit ("RSU") represents a contingent right to receive one Class A ordinary share, with no par value ("Class A Ordinary Share"), of Horizon Quantum Holdings Ltd. (the "Company") upon vesting, for no consideration.
F3: On September 12, 2026, 5,728 of Dr. Tan's RSU's vested.
F4: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date.
F5: The reported disposition to the Company reflects the settlement in cash of a portion of the RSUs which vested on September 12, 2026, at a price per ordinary share of $15.22, the last reported sales price of the Company's Class A Ordinary Shares on September 11, 2026.
F6: Each stock option has an exercise price of $2.88 and is exercisable for approximately 2.43499 Class A Ordinary Shares of the Company. In aggregate, Dr. Tan's spouse's stock options, once fully vested, are exercisable for 133,924 Class A Ordinary Shares of the Company.
F7: Of the 55,000 stock options, 37,811 stock options are currently fully vested and exercisable. The remaining stock options vest in five approximately equal quarterly installments beginning on November 20, 2026, subject to Dr. Tan's spouse's continued employment with the Company.
F8: As a result of the closing of the Company's business combination on March 19, 2026, Dr. Tan's spouse's 55,000 Legacy Horizon stock options were exchanged for 55,000 stock options of the Company of an equivalent economic value, with an exercise price per Class A Ordinary Share of $2.88.
Transaction history
JSON APIPurchases/sales include open-market and private transactions. Plan disclosure applies to the filing; individual rows may differ. “Not disclosed” is not “unplanned.”
The cutoff filters transaction history only. Company summaries and owner relationships show the latest available disclosures. Parser corrections can improve historical records.
| Transaction date | Company | Activity / security | Shares / units | Reported price | Reported value | Details |
|---|---|---|---|---|---|---|
| September 12, 2026 Filed Sep 16, 2026 01:31 UTC | Horizon Quantum Holdings Ltd. HQ · Entity 5127 | Exercise / conversionRestricted Stock Unit · Derivative | 5,728 | $0.00 Strike: $0.00 | $0.00 |
DisclosureSEC source: 0001213900-26-100280 · ownership.xml · derivative · entry 6 Tan Si-Hui · CIK 0002120880 · Chief Science Officer 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 85,931 Underlying: Class A Ordinary Shares · 5,728 shares Expires not disclosed Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event. F2 · derivative.exercise_price: Each restricted stock unit ("RSU") represents a contingent right to receive one Class A ordinary share, with no par value ("Class A Ordinary Share"), of Horizon Quantum Holdings Ltd. (the "Company") upon vesting, for no consideration. F3 · shares: On September 12, 2026, 5,728 of Dr. Tan's RSU's vested. F3 · derivative.exercise_date: On September 12, 2026, 5,728 of Dr. Tan's RSU's vested. F4 · derivative.exercise_date: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. F4 · derivative.expiration_date: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. Read SEC document |
| September 12, 2026 Filed Sep 16, 2026 01:31 UTC | Horizon Quantum Holdings Ltd. HQ · Entity 5127 | Disposition to issuerClass A Ordinary Shares | 2,991 | $15.22 | $45,523.02 |
DisclosureSEC source: 0001213900-26-100280 · ownership.xml · nonDerivative · entry 3 Tan Si-Hui · CIK 0002120880 · Chief Science Officer 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 2,737 F5 · date: The reported disposition to the Company reflects the settlement in cash of a portion of the RSUs which vested on September 12, 2026, at a price per ordinary share of $15.22, the last reported sales price of the Company's Class A Ordinary Shares on September 11, 2026. F5 · shares: The reported disposition to the Company reflects the settlement in cash of a portion of the RSUs which vested on September 12, 2026, at a price per ordinary share of $15.22, the last reported sales price of the Company's Class A Ordinary Shares on September 11, 2026. F5 · price: The reported disposition to the Company reflects the settlement in cash of a portion of the RSUs which vested on September 12, 2026, at a price per ordinary share of $15.22, the last reported sales price of the Company's Class A Ordinary Shares on September 11, 2026. Read SEC document |
| September 12, 2026 Filed Sep 16, 2026 01:31 UTC | Horizon Quantum Holdings Ltd. HQ · Entity 5127 | Exercise / conversionClass A Ordinary Shares | 5,728 | $0.00 | $0.00 |
DisclosureSEC source: 0001213900-26-100280 · ownership.xml · nonDerivative · entry 2 Tan Si-Hui · CIK 0002120880 · Chief Science Officer 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 5,728 Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event. F3 · date: On September 12, 2026, 5,728 of Dr. Tan's RSU's vested. F4 · shares: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. F4 · price: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. Read SEC document |
| August 20, 2026 Filed Sep 16, 2026 01:31 UTC | Horizon Quantum Holdings Ltd. HQ · Entity 5127 | GrantClass A Ordinary Shares | 3,600 | $0.00 | $0.00 |
DisclosureSEC source: 0001213900-26-100280 · ownership.xml · nonDerivative · entry 1 Tan Si-Hui · CIK 0002120880 · Chief Science Officer 10b5-1 filing: No plan indicated Ownership: Indirect · By Spouse Disclosed balance after: 3,600 F1 · date: On August 20, 2026 (the "August Grant Date"), Dr. Tan's spouse was granted a total of unvested 3,600 RSUs. The RSUs granted to Dr. Tan's spouse are subject to his continued employment with the Company and vest in accordance with the following schedule: One quarter (1/4) of the total number of RSUs vest on the first anniversary of the August Grant Date with the remaining three quarters (3/4) vesting in twelve approximately equal quarterly installments on 20th day of each fiscal quarter. F1 · shares: On August 20, 2026 (the "August Grant Date"), Dr. Tan's spouse was granted a total of unvested 3,600 RSUs. The RSUs granted to Dr. Tan's spouse are subject to his continued employment with the Company and vest in accordance with the following schedule: One quarter (1/4) of the total number of RSUs vest on the first anniversary of the August Grant Date with the remaining three quarters (3/4) vesting in twelve approximately equal quarterly installments on 20th day of each fiscal quarter. F2 · price: Each restricted stock unit ("RSU") represents a contingent right to receive one Class A ordinary share, with no par value ("Class A Ordinary Share"), of Horizon Quantum Holdings Ltd. (the "Company") upon vesting, for no consideration. Read SEC document |
| June 12, 2026 Filed Sep 16, 2026 01:31 UTC | Horizon Quantum Holdings Ltd. HQ · Entity 5127 | GrantRestricted Stock Unit · Derivative | 91,659 | $0.00 Strike: $0.00 | $0.00 |
DisclosureSEC source: 0001213900-26-100280 · ownership.xml · derivative · entry 5 Tan Si-Hui · CIK 0002120880 · Chief Science Officer 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 91,659 Underlying: Class A Ordinary Shares · 91,659 shares Expires not disclosed F2 · derivative.exercise_price: Each restricted stock unit ("RSU") represents a contingent right to receive one Class A ordinary share, with no par value ("Class A Ordinary Share"), of Horizon Quantum Holdings Ltd. (the "Company") upon vesting, for no consideration. F4 · shares: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. F4 · derivative.exercise_date: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. F4 · derivative.expiration_date: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. F4 · derivative.underlying_shares: On June 12, 2026 (the "June Grant Date"), Dr. Tan was granted a total of 91,659 unvested RSUs. The RSUs granted to Dr. Tan vest in sixteen approximately equal installments on successive quarterly anniversaries of the June Grant Date and are subject to Dr. Tan's continued employment with the Company through each applicable vesting date. Read SEC document |
| March 19, 2026 Filed Sep 16, 2026 01:31 UTC | Horizon Quantum Holdings Ltd. HQ · Entity 5127 | GrantStock Option (Right to Buy) · Derivative | 55,000 | Not disclosed Strike: $2.88 | Not disclosed |
DisclosureSEC source: 0001213900-26-100280 · ownership.xml · derivative · entry 4 Tan Si-Hui · CIK 0002120880 · Chief Science Officer 10b5-1 filing: No plan indicated Ownership: Indirect · By Spouse Disclosed balance after: 55,000 Underlying: Class A Ordinary Shares · 133,924 shares Expires 2035-02-01 F6 · derivative.exercise_price: Each stock option has an exercise price of $2.88 and is exercisable for approximately 2.43499 Class A Ordinary Shares of the Company. In aggregate, Dr. Tan's spouse's stock options, once fully vested, are exercisable for 133,924 Class A Ordinary Shares of the Company. F7 · date: Of the 55,000 stock options, 37,811 stock options are currently fully vested and exercisable. The remaining stock options vest in five approximately equal quarterly installments beginning on November 20, 2026, subject to Dr. Tan's spouse's continued employment with the Company. F7 · shares: Of the 55,000 stock options, 37,811 stock options are currently fully vested and exercisable. The remaining stock options vest in five approximately equal quarterly installments beginning on November 20, 2026, subject to Dr. Tan's spouse's continued employment with the Company. F8 · price: As a result of the closing of the Company's business combination on March 19, 2026, Dr. Tan's spouse's 55,000 Legacy Horizon stock options were exchanged for 55,000 stock options of the Company of an equivalent economic value, with an exercise price per Class A Ordinary Share of $2.88. F7 · derivative.exercise_date: Of the 55,000 stock options, 37,811 stock options are currently fully vested and exercisable. The remaining stock options vest in five approximately equal quarterly installments beginning on November 20, 2026, subject to Dr. Tan's spouse's continued employment with the Company. F6 · derivative.underlying_shares: Each stock option has an exercise price of $2.88 and is exercisable for approximately 2.43499 Class A Ordinary Shares of the Company. In aggregate, Dr. Tan's spouse's stock options, once fully vested, are exercisable for 133,924 Class A Ordinary Shares of the Company. Read SEC document |
| March 19, 2026 Filed Mar 25, 2026 20:21 UTC | Horizon Quantum Holdings Ltd. HQ · Entity 5127 | GrantStock Option (Right to Buy) · Derivative | 500,000 | Not disclosed Strike: $0.15 | Not disclosed |
DisclosureSEC source: 0001213900-26-034087 · ownership.xml · derivative · entry 1 Tan Si-Hui · CIK 0002120880 · Chief Science Officer 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 500,000 Underlying: Class A Ordinary Shares · 1,217,494 shares Expires 2032-03-01 F1 · derivative.exercise_price: Each stock option is exercisable for 2.43499 Class A Ordinary Shares of Horizon Quantum Holdings Ltd. (the "Company") at a price per share of $0.15. F2 · date: Stock options received as part of the business combination (the "Business Combination") contemplated by the Business Combination Agreement, dated as of September 9, 2025 (the "BCA"), by and among Horizon Quantum Computing Pte. Ltd. ("Legacy Horizon"), dMY Squared Technology Group, Inc., the Company and certain other parties, as described in the Registration Statement on Form F-4, as amended and supplemented (File No. 333-292737), initially filed with the U.S. Securities and Exchange Commission on January 14, 2026, and declared effective on February 17, 2026. Upon the closing of the Business Combination on March 19, 2026, Dr. Tan's stock options exercisable for Legacy Horizon ordinary shares awarded by Legacy Horizon were exchanged for substitute stock option awards of the Company of an equivalent economic value. F1 · shares: Each stock option is exercisable for 2.43499 Class A Ordinary Shares of Horizon Quantum Holdings Ltd. (the "Company") at a price per share of $0.15. F4 · price: Pursuant to the BCA and as a result of the closing of the Business Combination, Dr. Tan's 500,000 Legacy Horizon stock options were exchanged for 500,000 stock options of the Company of an equivalent economic value, with an exercise price per Class A Ordinary Share of $0.15. F3 · derivative.exercise_date: The stock options held by Dr. Tan are fully vested and exercisable. F1 · derivative.underlying_shares: Each stock option is exercisable for 2.43499 Class A Ordinary Shares of Horizon Quantum Holdings Ltd. (the "Company") at a price per share of $0.15. Read SEC document |
Value uses the disclosed total when available, otherwise shares × reported transaction price. It is not an estimate of exercise cash cost or investment performance.