Silverbox Corp Iv-A: 5%+ holders

As of November 7, 2026, 4 holders' latest Schedule 13D or 13G filings report owning 5% or more of Silverbox Corp Iv-A. The largest reported stake is W. R. Berkley Corporation's, at 9.4%. 18 filings are on record since August 12, 2025 (Schedule 13G/A, August 6, 2026).

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Key facts

• Filing 2026-11-06 · Reporting person: Barclays PLC · Sole voting: 93,900 · Shared voting: 0 · Sole dispositive: 93,900 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-11-06
• Filing 2026-10-09 · 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
• Filing 2026-08-12 · 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
• Filing 2026-08-06 · Reporting person: W. R. Berkley Corporation · Sole voting: 0 · Shared voting: 1,923,442 · Sole dispositive: 0 · Shared dispositive: 1,923,442 · SCHEDULE 13G/A, 2026-08-06
• Filed 2026-05-14 · Holder: Barclays PLC · Percent: 7% · SCHEDULE 13G

Silverbox Corp Iv-A has 18 Schedule 13D or 13G filings on record since 2025-08-12. 4 holders' latest filing reports 5% or more of common-stock. Each figure below is the holder's own, as filed, with the filing linked.

Holders

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What the Full Report on Silverbox Corp Iv-A covers

1. The Short Answer

2. Which Company This Is

3. What They Do, And How The Money Works

4. Who Runs It, And How To Reach Them

5. The Money: Funding, Valuation, Runway

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7. Warning Bells

8. Sources

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Voting and dispositive power, as filed

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The latest filing identifies Silverbox Corp Iv-A by CUSIP G81354105 and gives its principal executive office as 1250 S. Capital of Texas Highway, Building 2, Suite 285, Austin, TX 78746 (SCHEDULE 13G/A, 2026-11-06).

Timeline

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Questions about who owns Silverbox Corp Iv-A

Who owns Silverbox Corp Iv-A?

On this page, 4 holders' latest ownership filings report 5% or more of Silverbox Corp Iv-A: W. R. Berkley Corporation (9.4%, Schedule 13G/A, filed 2026-08-06), 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-A?

By the share each holder's latest filing reports, the largest holders of Silverbox Corp Iv-A on this page are W. R. Berkley Corporation (9.4%), Mizuho Financial Group, Inc. (8%) and Calamos Market Neutral Income Fund, a series of Calamos Investment Trust (7.8%).

When did W. R. Berkley Corporation buy into Silverbox Corp Iv-A?

The filings give report dates, not purchase dates. The earliest filing from W. R. Berkley Corporation on this page is the Schedule 13G, filed 2026-02-11, reporting 5.9%; its latest, Schedule 13G/A filed 2026-08-06, reports 9.4%.

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%); 18 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-A

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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.

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