As of November 6, 2026, Boundless Bio, Inc. is a publicly traded company (Nasdaq: BOLD); its largest reported holder is Fidelity (FMR), with 12% on Schedule 13G/A of February 5, 2026, then Tang Capital Management, LLC (11.3%) (Schedule 13G/A, February 5, 2026).
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Is Boundless Bio, Inc. a real, registered company?
- Boundless Bio, Inc. files with the SEC under CIK 1782303 (its SEC filings).
- Its shares are listed under the ticker BOLD on Nasdaq (SEC company record).
- Incorporated in Delaware; business address in La Jolla, California, 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 Boundless Bio, Inc. in our court records and SEC 8-K records (as of 2026-11-06).
- Layoffs: 1 exit or restructuring plan reported on Form 8-K, Item 2.05 (latest filed 2026-06-23).
- Ownership: 5%+ holders are reported on Schedule 13D or 13G; the latest names Zachary Hornby (filed 2026-08-27).
Who are Boundless Bio, Inc.'s owners and officers?
Boundless Bio, Inc.: incorporated in Delaware; business address in La Jolla, California; industry Pharmaceutical Preparations (Schedule 13G, 2026-08-27).
Officers and directors, each with the role and the filing that names them:
- : Director, Executive Officer (Form D, 2023-08-15)
- : Director (Form D, 2023-08-15)
- : Director (Form D, 2023-08-15)
- : Director (Form D, 2023-08-15)
- : Director (Form D, 2023-08-15)
- : Director (Form D, 2023-08-15)
- : Director (Form D, 2023-08-15)
- : Director (Form D, 2023-08-15)
| Report | Holder | Share |
|---|---|---|
| Schedule 13G, 2026-08-27 | Zachary Hornby | 9.8% |
| Schedule 13G, 2026-08-14 | Adar1 Capital Management, LLC | 8.8% |
| Schedule 13G/A, 2026-08-14 | Citadel Securities Group LP | 0.6% |
| Schedule 13G, 2026-06-29 | Tang Capital Management, LLC | 11.3% |
| Schedule 13G/A, 2026-02-17 | Nextech Vi Gp S.A. R.L. | 0% |
| Schedule 13G/A, 2026-02-05 | Fmr LLC | 12% |
| Schedule 13G, 2025-12-04 | Kenneth Griffin | 6.4% |
| Schedule 13G/A, 2025-08-14 | Ra Capital Management, L.P. | 0% |
Questions about who owns Boundless Bio, Inc.
Who owns Boundless Bio, Inc.?
On this page, 5 holders' latest ownership filings report 5% or more of Boundless Bio, Inc.: Fmr LLC (12%, Schedule 13G/A, filed 2026-02-05), Tang Capital Management, LLC (11.3%, Schedule 13G, filed 2026-06-29), Zachary Hornby (9.8%, Schedule 13G, filed 2026-08-27), Adar1 Capital Management, LLC (8.8%, Schedule 13G, filed 2026-08-14) and Kenneth Griffin (6.4%, Schedule 13G, filed 2025-12-04).
Who are the largest shareholders of Boundless Bio, Inc.?
By the share each holder's latest filing reports, the largest holders of Boundless Bio, Inc. on this page are Fmr LLC (12%), Tang Capital Management, LLC (11.3%) and Zachary Hornby (9.8%).
When did Fmr LLC buy into Boundless Bio, Inc.?
The filings give report dates, not purchase dates. The earliest filing from Fmr LLC on this page is the Schedule 13G/A, filed 2026-02-05, reporting 12%. 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%); 8 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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Which insiders own Boundless Bio, 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.
- Tang Capital Management LLC, a 10% owner: 3,033,618 shares (13.3% of shares outstanding), held indirectly (the form names the holder only in its footnotes), on a joint filing (Form 4, 2026-11-05).
- , a 10% owner: 3,033,618 shares (13.3% of shares outstanding), held indirectly (the form names the holder only in its footnotes), on a joint filing (Form 4, 2026-11-05).
- ARCH Venture Partners IX, L.P., a 10% owner: 1,181,766 shares (5.2% of shares outstanding), held indirectly (the form names the holder only in its footnotes), on a joint filing (Form 4, 2026-07-06).
- ARCH Venture Partners IX, LLC, a 10% owner: 1,181,766 shares (5.2% of shares outstanding), held indirectly (the form names the holder only in its footnotes), on a joint filing (Form 4, 2026-07-06).
- ARCH Venture Fund IX, L.P., a 10% owner: 1,181,766 shares (5.2% of shares outstanding), held indirectly (the form names the holder only in its footnotes), on a joint filing (Form 4, 2026-07-06).
Shares outstanding: 22,747,985 as of 2026-08-05, from the company's latest SEC cover page.
How much has Boundless Bio, Inc. raised?
| Filed | Sold | Offered |
|---|---|---|
| Form D, 2023-08-15 | $100M | $100M |
Red flags found
1 exit or restructuring plan on Form 8-K (latest Form 8-K, 2026-06-23).
Keep reading
More on Boundless Bio, Inc. and the records around it.
Boundless Bio, Inc. elsewhere on the record
- 5%+ stake filings Aug 2026
- Layoff notices Jun 2026
Companies that share a holder
- ADAR1 Capital Management, LLC also filed stake reports on 29 other companies: InMed Pharmaceuticals, Inc. (Oct 2026), Tenax Therapeutics, Inc. (Sep 2026), Adagio Medical Holdings, Inc. (Aug 2026)
- TANG CAPITAL MANAGEMENT, LLC also filed stake reports on 33 other companies: EyePoint, Inc. (Oct 2026), Skye Bioscience, Inc. (Oct 2026), Nano Dimension Ltd. (Aug 2026)
- Citadel Advisors LLC also filed stake reports on 58 other companies: Quantinuum Inc. (Oct 2026), REALLOYS INC. (Oct 2026), STARFIGHTERS SPACE, INC. (Oct 2026)
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