As of November 10, 2026, 3 holders' latest Schedule 13D or 13G filings report owning 5% or more of Silverbox Corp Iv. The largest reported stake is Mizuho Financial Group, Inc.'s, at 8%. 19 filings are on record since August 12, 2025 (Schedule 13G, February 12, 2026).
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Key facts
- · Reporting person: W. R. Berkley Corporation · Sole voting: 0 · Shared voting: 0 · Sole dispositive: 0 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-11-09
- · Reporting person: Barclays PLC · Sole voting: 93,900 · Shared voting: 0 · Sole dispositive: 93,900 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-11-06
- · Reporting person: Calamos Market Neutral Income Fund, a series of Calamos Investment Trust · Sole voting: 500,000 · Shared voting: 0 · Sole dispositive: 500,000 · Shared dispositive: 0 · SCHEDULE 13G, 2026-10-09
- · Reporting person: Aqr Capital Management LLC · Sole voting: 0 · Shared voting: 1,012,401 · Sole dispositive: 0 · Shared dispositive: 1,012,401 · SCHEDULE 13G/A, 2026-08-12
- · Holder: W. R. Berkley Corporation · Percent: 9.4% · SCHEDULE 13G/A
Silverbox Corp Iv has 19 Schedule 13D or 13G filings on record since 2025-08-12. 3 holders' latest filing reports 5% or more of class a ordinary shares, par value $0.0001 per share. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Mizuho Financial Group, Inc. | 8% | 1,645,673 | SCHEDULE 13G, 2026-02-12 | 2025-12-31 |
| Calamos Market Neutral Income Fund, a series of Calamos Investment Trust | 7.8% | 500,000 | SCHEDULE 13G, 2026-10-09 | 2026-09-30 |
| Polar Asset Management Partners Inc. | 7.2% | 1,480,000 | SCHEDULE 13G/A, 2025-08-14 | 2025-06-30 |
| Aqr Capital Management LLC | 4.95% | 1,012,401 | SCHEDULE 13G/A, 2026-08-12 | 2026-06-30 |
| The Goldman Sachs Group, Inc. | 3.2% | 654,022 | SCHEDULE 13G/A, 2025-11-10 | 2025-09-30 |
| Barclays PLC | 1.46% | 93,900 | SCHEDULE 13G/A, 2026-11-06 | 2026-09-30 |
| Highbridge Capital Management LLC | 1.4% | 280,000 | SCHEDULE 13G/A, 2025-11-14 | 2025-09-30 |
| Healthcare of Ontario Pension Plan Trust Fund | 0.5% | 100,000 | SCHEDULE 13G/A, 2025-08-13 | 2025-06-30 |
| Sculptor Capital LP | 0% | 0 | SCHEDULE 13G/A, 2026-02-13 | 2025-12-31 |
| W. R. Berkley Corporation | 0% | 0 | SCHEDULE 13G/A, 2026-11-09 | 2026-09-30 |
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More on Silverbox Corp Iv and the records around it.
Companies that share a holder
- Calamos Market Neutral Income Fund, a series of Calamos Investment Trust also filed stake reports on 2 other companies: Four Leaf Acquisition Corp (Sep 2025)
- Healthcare of Ontario Pension Plan Trust Fund also filed stake reports on 27 other companies: Cambridge Acquisition Corp. (Aug 2026), General Purpose Acquisition Corp. (May 2026), Artius II Acquisition Inc. (Feb 2026)
- Sculptor Capital LP also filed stake reports on 40 other companies: Helix Acquisition Corp. III (Oct 2026), Live Oak Acquisition Corp. VI (Oct 2026), Amanat Acquisition Corp (Aug 2026)
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What the Full Report on Silverbox Corp Iv covers
The Short Answer
Which Company This Is
What They Do, And How The Money Works
Who Runs It, And How To Reach Them
The Money: Funding, Valuation, Runway
Who Pays Them, And Who They Are Up Against
Warning Bells
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Calamos Market Neutral Income Fund, a series of Calamos Investment Trust | 500,000 | 0 | 500,000 | 0 | SCHEDULE 13G, 2026-10-09 |
| Aqr Capital Management LLC | 0 | 1,012,401 | 0 | 1,012,401 | SCHEDULE 13G/A, 2026-08-12 |
| AQR Capital Management Holdings, LLC | 0 | 1,012,401 | 0 | 1,012,401 | SCHEDULE 13G/A, 2026-08-12 |
| AQR Arbitrage, LLC | 0 | 1,012,401 | 0 | 1,012,401 | SCHEDULE 13G/A, 2026-08-12 |
| Barclays PLC | 93,900 | 0 | 93,900 | 0 | SCHEDULE 13G/A, 2026-11-06 |
| W. R. Berkley Corporation | 0 | 0 | 0 | 0 | SCHEDULE 13G/A, 2026-11-09 |
| Berkley Insurance Company | 0 | 0 | 0 | 0 | SCHEDULE 13G/A, 2026-11-09 |
The latest filing identifies Silverbox Corp Iv by CUSIP G81354105 and gives its principal executive office as 8701 Bee Cave Road, East Building, Suite 310, Austin, TX 78746 (SCHEDULE 13G/A, 2026-11-09).
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-12 | Barclays PLC | 4.74% | SCHEDULE 13G/A |
| 2025-08-13 | The Goldman Sachs Group, Inc. | 7.9% | SCHEDULE 13G/A |
| 2025-08-13 | Healthcare of Ontario Pension Plan Trust Fund | 0.5% | SCHEDULE 13G/A |
| 2025-08-14 | Highbridge Capital Management, LLC | 5.9% | SCHEDULE 13G |
| 2025-08-14 | Sculptor Capital LP | 5.87% | SCHEDULE 13G/A |
| 2025-08-14 | AQR Capital Management, LLC | 6.59% | SCHEDULE 13G/A |
| 2025-08-14 | Polar Asset Management Partners Inc. | 7.2% | SCHEDULE 13G/A |
| 2025-11-10 | The Goldman Sachs Group, Inc. | 3.2% | SCHEDULE 13G/A |
| 2025-11-14 | Highbridge Capital Management LLC | 1.4% | SCHEDULE 13G/A |
| 2026-02-11 | W. R. Berkley Corporation | 5.9% | SCHEDULE 13G |
| 2026-02-12 | Mizuho Financial Group, Inc. | 8% | SCHEDULE 13G |
| 2026-02-13 | Sculptor Capital LP | 0% | SCHEDULE 13G/A |
| 2026-05-08 | W. R. Berkley Corporation | 7.4% | SCHEDULE 13G/A |
| 2026-05-14 | Barclays PLC | 7% | SCHEDULE 13G |
| 2026-08-06 | W. R. Berkley Corporation | 9.4% | SCHEDULE 13G/A |
| 2026-08-12 | Aqr Capital Management LLC | 4.95% | SCHEDULE 13G/A |
| 2026-10-09 | Calamos Market Neutral Income Fund, a series of Calamos Investment Trust | 7.8% | SCHEDULE 13G |
| 2026-11-06 | Barclays PLC | 1.46% | SCHEDULE 13G/A |
| 2026-11-09 | W. R. Berkley Corporation | 0% | SCHEDULE 13G/A |
Questions about who owns Silverbox Corp Iv
Who owns Silverbox Corp Iv?
On this page, 3 holders' latest ownership filings report 5% or more of Silverbox Corp Iv: Mizuho Financial Group, Inc. (8%, Schedule 13G, filed 2026-02-12), Calamos Market Neutral Income Fund, a series of Calamos Investment Trust (7.8%, Schedule 13G, filed 2026-10-09) and Polar Asset Management Partners Inc. (7.2%, Schedule 13G/A, filed 2025-08-14).
Who are the largest shareholders of Silverbox Corp Iv?
By the share each holder's latest filing reports, the largest holders of Silverbox Corp Iv on this page are Mizuho Financial Group, Inc. (8%), Calamos Market Neutral Income Fund, a series of Calamos Investment Trust (7.8%) and Polar Asset Management Partners Inc. (7.2%).
When did Mizuho Financial Group, Inc. buy into Silverbox Corp Iv?
The filings give report dates, not purchase dates. The earliest filing from Mizuho Financial Group, Inc. on this page is the Schedule 13G, filed 2026-02-12, reporting 8%.
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%); 19 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 Silverbox Corp Iv
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| August 16, 2024 | IPO filing, Form 424B4 | $10 a share | IPO filings | Source |
| August 9, 2024 | IPO filing, Form S-1/A | — | IPO filings | Source |
| August 5, 2024 | IPO filing, Form S-1/A | — | IPO filings | Source |
| July 23, 2024 | IPO filing, Form S-1/A | — | 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.