As of November 7, 2026, 2 holders' latest Schedule 13D or 13G filings report owning 5% or more of Bambusa Therapeutics, Inc. The largest reported stake is RA Capital Management, L.P.'s, at 14.6%. 2 filings are on record since November 5, 2026 (Schedule 13D, November 6, 2026).
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Bambusa Therapeutics, Inc. has 2 Schedule 13D or 13G filings on record since 2026-11-05. 2 holders' latest filing reports 5% or more of common stock, par value $0.001 per share. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| RA Capital Management, L.P. | 14.6% | 7,429,758 | SCHEDULE 13D, 2026-11-06 | 2026-10-30 |
| 9.2% | 4,699,188 | SCHEDULE 13G, 2026-11-05 | 2026-10-29 |
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More on Bambusa Therapeutics, Inc. and the records around it.
The people at Bambusa Therapeutics, Inc.
- Derek DiRocco is also named on 1 other Form D filing: Stipple Bio, Inc. (Apr 2026)
Bambusa Therapeutics, Inc. elsewhere on the record
Companies that share a holder
- ATHOS KG also filed stake reports on 1 other company: BioNTech SE (May 2026)
- RA Capital Management, L.P. also filed stake reports on 100 other companies: SOLID BIOSCIENCES INC. (Nov 2026), LENZ THERAPEUTICS, INC. (Nov 2026), Alector, Inc. (Oct 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| RA Capital Management, L.P. | 0 | 7,429,758 | 0 | 7,429,758 | SCHEDULE 13D, 2026-11-06 |
| Peter Kolchinsky | 0 | 7,429,758 | 0 | 7,429,758 | SCHEDULE 13D, 2026-11-06 |
| Rajeev Shah | 0 | 7,429,758 | 0 | 7,429,758 | SCHEDULE 13D, 2026-11-06 |
| RA Capital Healthcare Fund, L.P. | 0 | 5,933,787 | 0 | 5,933,787 | SCHEDULE 13D, 2026-11-06 |
| Athos Kg | 0 | 4,579,067 | 0 | 4,579,067 | SCHEDULE 13G, 2026-11-05 |
| Objektgesellschaft Salzufer 1 GmbH | 0 | 4,579,067 | 0 | 4,579,067 | SCHEDULE 13G, 2026-11-05 |
| Salzufer Holding Inc. | 0 | 4,579,067 | 0 | 4,579,067 | SCHEDULE 13G, 2026-11-05 |
| Thomas Maier | 120,121 | 4,579,067 | 120,121 | 4,579,067 | SCHEDULE 13G, 2026-11-05 |
The latest filing identifies Bambusa Therapeutics, Inc. by CUSIP 058937103 and gives its principal executive office as 22 Boston Wharf Road, Floor 7, Boston, MA 02210 (SCHEDULE 13D, 2026-11-06).
What the percentages are based on
See the responses to Item 11 on the attached cover pages, which were calculated based on 50,942,430 shares of Common Stock outstanding immediately after the Issuer's initial public offering, as reported in the Issuer's final prospectus dated October 29, 2026, filed with the Securities and Exchange Commission on October 30, 2026, assuming no exercise of the underwriters' option to purchase additional shares.Thomas Maier, SCHEDULE 13G, 2026-11-05
Source of funds (Item 3)
Prior to the Issuer's initial public offering (the "IPO"), (i) the Fund purchased 2,844,910 shares of Series A-1 preferred stock of the Issuer and 299,948 shares of Series A-2 preferred stock of the Issuer; and (ii) the Nexus Fund III purchased 1,278,148 shares of Series A-1 preferred stock of the Issuer and 52,932 shares of Series A-2 preferred stock of the Issuer. The foregoing share numbers give effect to a 1.54485-for-1 forward stock split of the Issuer's outstanding capital stock effected on October 23, 2026. The aggregate purchase price of the foregoing securities was $27,777,749.RA Capital Management, L.P., SCHEDULE 13D, 2026-11-06
Purpose of Transaction (Item 4)
RA Capital Management, L.P.
The Reporting Persons acquired the common stock reported herein for investment purposes and not with an intent, purpose or effect of changing control of the Issuer. The Reporting Persons may, from time to time, acquire additional equity securities or debt securities of the Issuer, which debt securities may be convertible or non-convertible, secured or unsecured, and could involve the monetization of potential revenue streams deriving from development-stage or commercial programs of the Issuer, or dispose of Issuer securities they beneficially own, on the open market or in private transactions or otherwise (including by means of 10b5-1 programs), consistent with their investment purposes and in amounts, on such terms and at such times as to be determined by the Reporting Persons based upon a number of factors, including, without limitation, their ongoing assessment of the Issuer's business prospects, the availability of Issuer securities at prices that would make the purchase or sale of such securities desirable, prevailing market conditions, the availability of other investment opportunities, and/or other considerations. In addition, consistent with their investment purpose, the Reporting Persons may engage in communications with persons associated with the Issuer, including stockholders of the Issuer, officers of the Issuer, members of the board of directors of the Issuer, and/or or other third parties, to discuss matters regarding the Issuer, including but not limited to …The first part of Item 4 of the SCHEDULE 13D filed 2026-11-06; the filing has the rest
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2026-11-05 | Thomas Maier | 9.2% | SCHEDULE 13G |
| 2026-11-06 | RA Capital Management, L.P. | 14.6% | SCHEDULE 13D |
Questions about who owns Bambusa Therapeutics, Inc.
Who owns Bambusa Therapeutics, Inc.?
On this page, 2 holders' latest ownership filings report 5% or more of Bambusa Therapeutics, Inc.: RA Capital Management, L.P. (14.6%, Schedule 13D, filed 2026-11-06) and Thomas Maier (9.2%, Schedule 13G, filed 2026-11-05).
Who are the largest shareholders of Bambusa Therapeutics, Inc.?
By the share each holder's latest filing reports, the largest holders of Bambusa Therapeutics, Inc. on this page are RA Capital Management, L.P. (14.6%) and Thomas Maier (9.2%).
When did RA Capital Management, L.P. buy into Bambusa Therapeutics, Inc.?
The filings give report dates, not purchase dates. The earliest filing from RA Capital Management, L.P. on this page is the Schedule 13D, filed 2026-11-06, reporting 14.6%.
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%); 2 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 Bambusa Therapeutics, Inc.
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| February 26, 2025 | Form D, private offering | $53.27M sold | Form D page | Source |
| January 8, 2025 | Form D, private offering | $9M sold | Form D page | Source |
| January 8, 2025 | Form D, private offering | $5.10M sold | Form D page | 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.