As of November 10, 2026, Octave Specialty Group Inc is a publicly traded company (NYSE: OSG); its largest reported holder is BlackRock, with 7.6% on Schedule 13G/A of October 17, 2025, then BlackRock (6.5%). The largest insider holding is Claude LeBlanc, the chief executive and a director, with 1,072,032 shares (2.4% of shares outstanding), per Form 4 of October 6, 2026 (Schedule 13G/A, October 17, 2025).
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Is Octave Specialty Group Inc a real, registered company?
- Octave Specialty Group Inc files with the SEC under CIK 874501 (its SEC filings).
- Its shares are listed under the ticker OSG on NYSE (SEC company record).
- Incorporated in Delaware; business address in New York, New York, as its SEC filings state.
- Court and bankruptcy records: see Before you sign or pay below.
Before you sign or pay
- Court and bankruptcy: No federal court case or bankruptcy filing found under Octave Specialty Group Inc in our court records and SEC 8-K records (as of 2026-11-10).
- Ownership: 5%+ holders are reported on Schedule 13D or 13G; the latest names BlackRock (filed 2026-10-27).
Who are Octave Specialty Group Inc's owners and officers?
Octave Specialty Group Inc: incorporated in Delaware; business address in New York, New York; industry Surety Insurance (Schedule 13G/A, 2026-10-30).
| Report | Holder | Share |
|---|---|---|
| Schedule 13G/A, 2026-10-30 | Vanguard Capital Management | 4.8% |
| Schedule 13G, 2026-10-27 | Blackrock Portfolio Management LLC | 6.5% |
| Schedule 13G, 2026-07-31 | Vanguard Capital Management | 5.04% |
| Schedule 13G/A, 2026-05-11 | Western Standard LLC | 4.99% |
| Schedule 13G/A, 2026-05-11 | Jane Street Group, LLC | 1.7% |
| Schedule 13G/A, 2026-03-27 | The Vanguard Group | 0% |
| Schedule 13G, 2026-02-12 | Western Standard LLC | 5.87% |
| Schedule 13G, 2026-02-11 | Jane Street Group, LLC | 5.4% |
| Schedule 13G/A, 2025-11-13 | G1 Execution Services, LLC | 2.2% |
| Schedule 13G/A, 2025-10-17 | Blackrock, Inc. | 7.6% |
| Schedule 13G/A, 2025-10-09 | Dimensional Fund Advisors LP | 4.6% |
| Schedule 13G, 2025-08-14 | Sig Brokerage, LP | 5.1% |
Questions about who owns Octave Specialty Group Inc
Who owns Octave Specialty Group Inc?
On this page, 3 holders' latest ownership filings report 5% or more of Octave Specialty Group Inc: Blackrock, Inc. (7.6%, Schedule 13G/A, filed 2025-10-17), Blackrock Portfolio Management LLC (6.5%, Schedule 13G, filed 2026-10-27) and Sig Brokerage, LP (5.1%, Schedule 13G, filed 2025-08-14).
Who are the largest shareholders of Octave Specialty Group Inc?
By the share each holder's latest filing reports, the largest holders of Octave Specialty Group Inc on this page are Blackrock, Inc. (7.6%), Blackrock Portfolio Management LLC (6.5%) and Sig Brokerage, LP (5.1%).
When did Blackrock, Inc. buy into Octave Specialty Group Inc?
The filings give report dates, not purchase dates. The earliest filing from Blackrock, Inc. on this page is the Schedule 13G/A, filed 2025-10-17, reporting 7.6%. That earliest filing is itself an amendment, which updates an earlier report.
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%); 12 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.
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What the Full Report on Octave Specialty Group Inc 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
Sources
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Which insiders own Octave Specialty Group Inc shares?
Directors, officers and holders of 10% or more report their shares on Forms 3, 4 and 5. Each line is the latest such report, largest holding first.
- , the chief executive and a director: 1,072,032 shares (2.4% of shares outstanding) (Form 4, 2026-10-06).
- , the chief financial officer and executive vice president: 267,096 shares (0.59% of shares outstanding) (Form 4, 2026-10-06).
- , a director: 217,807 shares (0.48% of shares outstanding) (Form 4, 2025-09-30).
- , a director: 205,477 shares (0.46% of shares outstanding) (Form 4, 2025-09-30).
- , the general counsel and senior md: 205,256 shares (0.46% of shares outstanding) (Form 4, 2025-10-01).
Shares outstanding: 45,061,214 as of 2026-11-05, from the company's latest SEC cover page.
How much has Octave Specialty Group Inc raised?
Acquisitions reported on Form 8-K, Item 2.01: completed an acquisition (2025-11-03).
Keep reading
More on Octave Specialty Group Inc and the records around it.
Octave Specialty Group Inc elsewhere on the record
- 5%+ stake filings Oct 2026
Companies that share a holder
- Western Standard LLC also filed stake reports on 1 other company: Green Dot Corporation (May 2026)
- G1 Execution Services, LLC also filed stake reports on 45 other companies: AmpliTech Group, Inc. (Aug 2026), Bitdeer Technologies Group (Aug 2026), Compass Diversified Holdings (Aug 2026)
- JANE STREET GROUP, LLC also filed stake reports on 73 other companies: AXT INC (Nov 2026), BIOVIE INC. (Nov 2026), Bitdeer Technologies Group (Nov 2026)
Related pages
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