Reported relationships
Latest disclosed role at each company.
| Company | Last reported as | Report date | Published |
|---|---|---|---|
| DEEP FISSION, INC.NONE · Entity 5748 | Chief Executive Officer | March 09, 2026 | March 10, 2026 |
| Deep Isolation Nuclear, Inc.DBHL · Entity 9903 | Director · 10% owner · Chair of the Board | October 06, 2026 | October 09, 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.
DEEP FISSION, INC.
Report date March 09, 2026 · Filed March 10, 2026
| Security / award | Ownership account | Disclosed shares / units | Disclosure context |
|---|---|---|---|
| Employee Stock Option (right to buy)SEC Table II · derivative / convertible security · Conversion / exercise price $15.00 · Expires 2036-03-09 | Direct | 4,150,300 |
Reported balance
After 2026-03-09 transaction · row 1
Instrument identity requires review; Table II rows are not merged.
1 source rowRow 1 · 2026-03-09 · Grant · Acquired 2,600,000 · Balance 4,150,300 F1: Date at which first vesting occurs is indicated. One-fourth of the total number of options to purchase the Company's common stock vests on the first vesting date shown and an additional one-thirty sixth on each month thereafter until fully vested. |
Filing footnotes · ownership attribution and instrument terms
F1: Date at which first vesting occurs is indicated. One-fourth of the total number of options to purchase the Company's common stock vests on the first vesting date shown and an additional one-thirty sixth on each month thereafter until fully vested.
Deep Isolation Nuclear, Inc.
Report date October 06, 2026 · Filed October 09, 2026
| Security / award | Ownership account | Disclosed shares / units | Disclosure context |
|---|---|---|---|
| Common StockSEC Table I · non-derivative | Direct | 11,771,267 |
Reported balance
After 2026-10-06 transaction · row 1
Account or security details depend on footnotes; rows are not merged.
1 source rowRow 1 · 2026-10-06 · Grant · Acquired 23,214 · Balance 11,771,267 F1: Represents a grant of restricted stock units ("RSUs") to the Reporting Person pursuant to the Deep Isolation Nuclear, Inc. 2025 Equity Incentive Plan. Each RSU represents a contingent right to receive one share of common stock upon vesting. The RSUs shall vest on September 29, 2027, subject to the Reporting Person's continued service through each vesting date. Conversion of the RSUs into shares of common stock of the Issuer upon vesting is deferred until the earliest of the following events to occur: (i) a change of control of the Issuer, (ii) a separation of service as a director by the Reporting Person, or (iii) death of the Reporting Person. |
Filing footnotes · ownership attribution and instrument terms
F1: Represents a grant of restricted stock units ("RSUs") to the Reporting Person pursuant to the Deep Isolation Nuclear, Inc. 2025 Equity Incentive Plan. Each RSU represents a contingent right to receive one share of common stock upon vesting. The RSUs shall vest on September 29, 2027, subject to the Reporting Person's continued service through each vesting date. Conversion of the RSUs into shares of common stock of the Issuer upon vesting is deferred until the earliest of the following events to occur: (i) a change of control of the Issuer, (ii) a separation of service as a director by the Reporting Person, or (iii) death of the Reporting Person.
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 |
|---|---|---|---|---|---|---|
| October 06, 2026 Filed Oct 9, 2026 00:34 UTC | Deep Isolation Nuclear, Inc. DBHL · Entity 9903 | GrantCommon Stock | 23,214 | $0.00 | $0.00 |
DisclosureSEC source: 0001213900-26-108177 · ownership.xml · nonDerivative · entry 1 Muller Elizabeth · CIK 0002081850 · Director · 10% owner · Chair of the Board 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 11,771,267 F1 · security: Represents a grant of restricted stock units ("RSUs") to the Reporting Person pursuant to the Deep Isolation Nuclear, Inc. 2025 Equity Incentive Plan. Each RSU represents a contingent right to receive one share of common stock upon vesting. The RSUs shall vest on September 29, 2027, subject to the Reporting Person's continued service through each vesting date. Conversion of the RSUs into shares of common stock of the Issuer upon vesting is deferred until the earliest of the following events to occur: (i) a change of control of the Issuer, (ii) a separation of service as a director by the Reporting Person, or (iii) death of the Reporting Person. Read SEC document |
| March 09, 2026 Filed Mar 10, 2026 17:27 UTC | DEEP FISSION, INC. NONE · Entity 5748 | GrantEmployee Stock Option (right to buy) · Derivative | 2,600,000 | $0.00 Strike: $15.00 | $0.00 |
DisclosureSEC source: 0001104659-26-025950 · tm268353-5_4seq1.xml · derivative · entry 1 Muller Elizabeth · CIK 0002081850 · Chief Executive Officer 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 4,150,300 Underlying: Common Stock · 2,600,000 shares Expires 2036-03-09 F1 · derivative.exercise_date: Date at which first vesting occurs is indicated. One-fourth of the total number of options to purchase the Company's common stock vests on the first vesting date shown and an additional one-thirty sixth on each month thereafter until fully vested. Read SEC document |
| December 09, 2025 Filed Dec 12, 2025 17:02 UTC | DEEP FISSION, INC. NONE · Entity 5748 | GrantStock Option (right to buy) · Derivative | 183,150 | $0.00 Strike: $2.73 | $0.00 |
DisclosureSEC source: 0001104659-25-120704 · tm2531523-5_4seq1.xml · derivative · entry 2 Muller Elizabeth · CIK 0002081850 · Chief Executive Officer 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 994,849 Underlying: shares of Common Stock · 183,150 shares Expires 2035-12-09 F2 · derivative.exercise_date: The stock options vest over four years, with 25% of the award vesting on the first anniversary of the December 9, 2025 grant date and the remaining 75% vesting in equal monthly installments thereafter, subject to the Reporting Person's continued service through each vesting date. Read SEC document |
| December 09, 2025 Filed Dec 12, 2025 17:02 UTC | DEEP FISSION, INC. NONE · Entity 5748 | GrantRestricted Stock Units | 549,451 | $0.00 | $0.00 |
DisclosureSEC source: 0001104659-25-120704 · tm2531523-5_4seq1.xml · nonDerivative · entry 1 Muller Elizabeth · CIK 0002081850 · Chief Executive Officer 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 549,451 F1 · kind: Each restricted stock unit represents the contingent right to receive one share of the Issuer's common stock upon vesting. The units vest over four years, with 25% of the award vesting on the first anniversary of the December 9, 2025 grant date and the remaining 75% vesting in equal monthly installments thereafter, subject to the Reporting Person's continued service through each vesting date. Restricted stock units do not have an expiration date. Read SEC document |
| November 19, 2025 Filed Nov 21, 2025 11:12 UTC | Deep Isolation Nuclear, Inc. NONE · Entity 9903 | GrantCommon Stock | 43,333 | $0.00 | $0.00 |
DisclosureSEC source: 0001213900-25-113423 · ownership.xml · nonDerivative · entry 1 Muller Elizabeth · CIK 0002081850 · Director · 10% owner 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 11,748,053 F1 · kind: Represents the grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's common stock upon settlement. The RSUs shall fully vest in 1 year and are subject to a deferral based on the earlier to occur of a change of control, a separation of service as a director, and death. Read SEC document |
| October 01, 2025 Filed Oct 7, 2025 18:48 UTC | Deep Isolation Nuclear, Inc. NONE · Entity 9903 | GrantStock Option (Right to Buy) · Derivative | 10,833 | $0.00 Strike: $3.00 | $0.00 |
DisclosureSEC source: 0001213900-25-097155 · ownership.xml · derivative · entry 2 Muller Elizabeth · CIK 0002081850 · Director · 10% owner 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 10,833 Underlying: Common Shares · 10,833 shares Expires 2035-10-01 F2 · derivative.exercise_date: The Stock Option is subject to a 4-year vesting schedule, whereby 1/48th of the option shares will vest monthly beginning on October 1, 2025, subject to Reporting Person's continued service through each vesting date. Read SEC document |
| October 01, 2025 Filed Oct 7, 2025 18:48 UTC | Deep Isolation Nuclear, Inc. NONE · Entity 9903 | GrantCommon Stock | 32,500 | $0.00 | $0.00 |
DisclosureSEC source: 0001213900-25-097155 · ownership.xml · nonDerivative · entry 1 Muller Elizabeth · CIK 0002081850 · Director · 10% owner 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 11,737,220 F1 · kind: Represents the grant of restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of the Issuer's common stock upon settlement. The RSUs are subject to a 4-year vesting period, whereby 1/48th of the RSUs will vest monthly beginning October 1, 2025, subject to the Reporting Person's continuous service through each vesting date. Read SEC document |
| September 05, 2025 Filed Sep 9, 2025 17:16 UTC | DEEP FISSION, INC. NONE · Entity 5748 | GrantCommon Stock | 5,057,855 | Not disclosed | Not disclosed |
DisclosureSEC source: 0001415889-25-023993 · form4-09092025_090929.xml · nonDerivative · entry 2 Muller Elizabeth · CIK 0002081850 · Director · President and Chief Executive 10b5-1 filing: No plan indicated Ownership: Indirect · By Muller Family Trust Disclosed balance after: 5,057,855 F1 · price: Received in connection with the Issuer's merger (the "Merger") with Deep Fission Inc. ("Legacy Deep Fission") in accordance with the terms of the Agreement and Plan of Merger and Reorganization dated as of September 5, 2025, by and among the Issuer (f/k/a Surfside Acquisition Inc.), Deep Fission Acquisition Co. and Legacy Deep Fission (the "Merger Agreement"), in exchange for shares of Legacy Deep Fission common stock. Pursuant to the terms of the Merger Agreement, at the effective time of the Merger, each issued and outstanding share of Legacy Deep Fission common stock was converted into the right to receive 17.32142 shares of the Issuer's common stock, rounded to the nearest whole share. F2 · ownership.nature: Ms. Muller controls the right to vote and dispose of the shares held by the Muller Family Trust (the "Trust") and accordingly, may be deemed to beneficially own the shares held by the Trust. Ms. Muller expressly disclaims beneficial ownership of all securities held by the Trust except to the extent of her pecuniary interest therein. Read SEC document |
| September 05, 2025 Filed Sep 9, 2025 17:16 UTC | DEEP FISSION, INC. NONE · Entity 5748 | GrantCommon Stock | 5,196,426 | Not disclosed | Not disclosed |
DisclosureSEC source: 0001415889-25-023993 · form4-09092025_090929.xml · nonDerivative · entry 1 Muller Elizabeth · CIK 0002081850 · Director · President and Chief Executive 10b5-1 filing: No plan indicated Ownership: Direct Disclosed balance after: 5,196,426 F1 · price: Received in connection with the Issuer's merger (the "Merger") with Deep Fission Inc. ("Legacy Deep Fission") in accordance with the terms of the Agreement and Plan of Merger and Reorganization dated as of September 5, 2025, by and among the Issuer (f/k/a Surfside Acquisition Inc.), Deep Fission Acquisition Co. and Legacy Deep Fission (the "Merger Agreement"), in exchange for shares of Legacy Deep Fission common stock. Pursuant to the terms of the Merger Agreement, at the effective time of the Merger, each issued and outstanding share of Legacy Deep Fission common stock was converted into the right to receive 17.32142 shares of the Issuer's common stock, rounded to the nearest whole share. 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.