As of November 6, 2026, 2 holders' latest Schedule 13D or 13G filings report owning 5% or more of Onconetix, Inc. The largest reported stake is Altos Venture AG's, at 35.8%. 3 filings are on record since July 16, 2025 (Schedule 13D/A, July 16, 2025).
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Key facts
- · Reporting person: Keystone Capital Partners, LLC · Sole voting: 0 · Shared voting: 419,298 · Sole dispositive: 0 · Shared dispositive: 419,298 · SCHEDULE 13G/A, 2026-11-05
- · Holder: Keystone Capital Partners, LLC · Percent: 6.1% · SCHEDULE 13G
- · Holder: Altos Venture AG · Percent: 35.8% · SCHEDULE 13D/A
Onconetix, Inc. has 3 Schedule 13D or 13G filings on record since 2025-07-16. 2 holders' latest filing reports 5% or more of common stock, par value $0.00001 per share. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Altos Venture AG | 35.8% | 273,230 | SCHEDULE 13D/A, 2025-07-16 | 2025-07-14 |
| Keystone Capital Partners, LLC | 6.32% | 419,298 | SCHEDULE 13G/A, 2026-11-05 | 2026-09-30 |
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More on Onconetix, Inc. and the records around it.
Onconetix, Inc. elsewhere on the record
- Leadership changes Apr 2026
- Who owns it
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Keystone Capital Partners, LLC | 0 | 419,298 | 0 | 419,298 | SCHEDULE 13G/A, 2026-11-05 |
| RANZ Group LLC | 0 | 419,298 | 0 | 419,298 | SCHEDULE 13G/A, 2026-11-05 |
| Fredric Zaino | 0 | 419,298 | 0 | 419,298 | SCHEDULE 13G/A, 2026-11-05 |
The latest filing identifies Onconetix, Inc. by CUSIP 68237Q401 and gives its principal executive office as 201 E. Fifth Street, Suite 1900, Cincinnati, OH 45202 (SCHEDULE 13G/A, 2026-11-05).
Purpose of Transaction (Item 4)
Altos Venture AG
The Reporting Person purchased the aforementioned securities for investment purposes with the aim of increasing the value of its investments and the Issuer. Subject to applicable legal requirements, the Reporting Person may purchase additional securities of the Issuer from time to time in open market or private transactions, depending on its evaluation of the Issuer's business, prospects and financial condition, the market for the Issuer's securities, other developments concerning the Issuer, the reaction of the Issuer to the Reporting Person's ownership of the Issuer's securities, other opportunities available to the Reporting Person, and general economic, money market and stock market conditions. In addition, depending upon the factors referred to above, the Reporting Person may dispose of all or a portion of its securities of the Issuer at any time (including by means of programs adopted pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934 (the "Act")). The Reporting Person reserves the right to increase or decrease its holdings on such terms and at such times as it may decide. Except as set forth in this Item 4 and Item 6 below, the Reporting Person has no present plan or proposal that relates to or would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D of the Act. However, the Reporting Person reserves the right to propose or participate in future transactions which may result in one or more of such actions, …The first part of Item 4 of the SCHEDULE 13D/A filed 2025-07-16; the filing has the rest
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-07-16 | Altos Venture AG | 35.8% | SCHEDULE 13D/A |
| 2026-07-27 | Keystone Capital Partners, LLC | 6.1% | SCHEDULE 13G |
| 2026-11-05 | Keystone Capital Partners, LLC | 6.32% | SCHEDULE 13G/A |
Questions about who owns Onconetix, Inc.
Who owns Onconetix, Inc.?
On this page, 2 holders' latest ownership filings report 5% or more of Onconetix, Inc.: Altos Venture AG (35.8%, Schedule 13D/A, filed 2025-07-16) and Keystone Capital Partners, LLC (6.32%, Schedule 13G/A, filed 2026-11-05).
Who are the largest shareholders of Onconetix, Inc.?
By the share each holder's latest filing reports, the largest holders of Onconetix, Inc. on this page are Altos Venture AG (35.8%) and Keystone Capital Partners, LLC (6.32%).
When did Altos Venture AG buy into Onconetix, Inc.?
The filings give report dates, not purchase dates. The earliest filing from Altos Venture AG on this page is the Schedule 13D/A, filed 2025-07-16, reporting 35.8%. 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%); 3 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 Onconetix, Inc.
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| April 24, 2026 | Leadership change: Sammy Dorf appointed, Chairman of the Board, and 1 more | — | Leadership changes | Source |
| October 7, 2025 | Form D, private offering | $12.98M 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.