Onconetix (ONCO) 13G: Keystone Capital reports 6.1% beneficial stake

Rhea-AI Filing Summary

Onconetix, Inc. has a Schedule 13G reporting that Keystone Capital Partners, LLC, together with RANZ Group LLC and Fredric Zaino, collectively report beneficial ownership of 223,717 shares of common stock. This represents approximately 6.1% of the 3,691,492 shares outstanding as of June 5, 2026.

The shares are held through Keystone, which is managed by RANZ Group and controlled by Mr. Zaino. All three reporting persons share voting and dispositive power over the 223,717 shares and have no sole voting or dispositive power. They note additional securities—warrants, preferred stock, and a common stock purchase agreement—are subject to a 4.99% beneficial ownership limitation and are excluded from the reported ownership.

Key Figures

Beneficially owned shares: 223,717 shares Ownership percentage: 6.1% Shares outstanding baseline: 3,691,492 shares +5 more

8 metrics

Beneficially owned shares 223,717 shares Shares of Onconetix common stock reported as beneficially owned by each reporting person

Ownership percentage 6.1% Percentage of Onconetix common stock represented by 223,717 shares

Shares outstanding baseline 3,691,492 shares Onconetix common shares outstanding as of June 5, 2026 used for ownership calculation

Warrant shares excluded 1,214,228 shares Shares issuable upon exercise of warrants held by Keystone, excluded from beneficial ownership

Preferred conversion shares excluded 12,195 shares Shares issuable upon conversion of preferred stock at alternate conversion price of $0.82

CSPA capacity excluded 99,742,303 shares Shares issuable under a common stock purchase agreement with Keystone, subject to cap

Beneficial ownership cap 4.99% Limit above which additional issuances to the holder are prohibited

Alternate conversion price $0.82 Price used to calculate shares issuable upon conversion of preferred stock held by Keystone

Key Terms

beneficial ownership, Rule 13d-3, common stock purchase agreement, alternate conversion price, +2 more

6 terms

beneficial ownership financial

"may be deemed to own beneficially all of the Shares (constituting approximately 6.1%"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

Rule 13d-3 regulatory

"By reason of the provisions of Rule 13d-3 of the Securities Exchange Act of 1934"

Rule 13d-3 defines who is treated as the beneficial owner of a company’s shares for U.S. securities disclosure rules — essentially anyone who has the power to vote or direct how shares are voted, or the power to buy or sell them, even if they don’t hold the certificates. For investors this matters because crossing certain ownership thresholds triggers public filing and disclosure obligations and signals potential control or influence, much like having the keys to a car implies you can drive it even if it’s registered to someone else.

common stock purchase agreement financial

"99,742,303 shares issuable pursuant to a common stock purchase agreement by and between"

A common stock purchase agreement is a legal contract that spells out the deal when someone buys ordinary shares in a company, specifying how many shares, the price, payment method, and any conditions for the sale. For investors it matters because it defines ownership rights, timing and protections—like a receipt plus rules for a big purchase—so it determines how and when an investor actually acquires voting power and potential returns.

alternate conversion price financial

"shares issuable upon conversion of shares of preferred stock held by Keystone, at an alternate conversion price of $0.82"

pecuniary interest financial

"disclaim beneficial ownership of any of the securities covered by this statement, except to the extent of any pecuniary interest therein"

dispositive power financial

"Shared Dispositive Power 223,717.00"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 07/27/2026 - 01:24 PM Accepted by SEC EDGAR 07/27/2026 - 01:24 PM Learn about SEC filing dates

FAQ

What percentage of Onconetix (ONCO) does Keystone Capital Partners report owning?

Keystone Capital Partners, together with related reporting persons, reports beneficial ownership of 6.1% of Onconetix’s common stock, based on 3,691,492 shares outstanding as of June 5, 2026.

How many Onconetix (ONCO) shares are reported as beneficially owned in this Schedule 13G?

The reporting persons collectively report 223,717 shares of Onconetix common stock as beneficially owned, with shared voting and dispositive power over all 223,717 shares through Keystone Capital Partners.

Who are the reporting persons in the Onconetix (ONCO) Schedule 13G filing?

The reporting persons are Keystone Capital Partners, LLC, RANZ Group LLC, and Fredric Zaino. Keystone holds the shares, RANZ Group manages Keystone, and Mr. Zaino controls RANZ Group, giving each shared beneficial ownership under Rule 13d-3.

What additional Onconetix (ONCO) securities related to Keystone are excluded from the 13G ownership figure?

Excluded are 1,214,228 shares issuable upon warrant exercise, 12,195 shares from preferred stock conversion at $0.82, and 99,742,303 shares under a common stock purchase agreement, all limited by a 4.99% beneficial ownership cap.

Do the reporting persons in the Onconetix (ONCO) 13G have sole or shared voting power?

Each reporting person has 0 shares with sole voting power and 223,717 shares with shared voting power. They likewise have 0 shares with sole dispositive power and 223,717 shares with shared dispositive power.

On what share count is the 6.1% ownership of Onconetix (ONCO) based?

The 6.1% ownership is calculated using 3,691,492 shares of common stock outstanding as of June 5, 2026, as reported by Onconetix in its June 16, 2026 prospectus (Registration No. 333-296615).

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Onconetix, Inc.

(Name of Issuer)

Common stock, par value $0.00001 per share

(Title of Class of Securities)

68237Q401

(CUSIP Number)

07/20/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 68237Q401

1

Names of Reporting Persons

Keystone Capital Partners, LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 223,717.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 223,717.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

223,717.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.1 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: The percentages used herein are calculated based upon 3,691,492 shares of common stock outstanding as of June 5, 2026, as reported by the Company in its Prospectus dated June 16, 2026 (Registration No. 333-296615), filed with the SEC on June 17, 2026. Amount beneficially owned excludes (i) 1,214,228 shares issuable upon exercise of warrants held by Keystone, (ii) 12,195 shares issuable upon conversion of shares of preferred stock held by Keystone, based on an alternate conversion price of $0.82, and (iii) 99,742,303 shares issuable pursuant to a common stock purchase agreement by and between the Company and Keystone, which in each case are subject to a prohibition on issuance if such issuance would result in the holder beneficially owning over 4.99% of the common stock.

SCHEDULE 13G

CUSIP Number(s): 68237Q401

1

Names of Reporting Persons

RANZ Group LLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 223,717.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 223,717.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

223,717.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.1 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: The percentages used herein are calculated based upon 3,691,492 shares of common stock outstanding as of June 5, 2026, as reported by the Company in its Prospectus dated June 16, 2026 (Registration No. 333-296615), filed with the SEC on June 17, 2026. Amount beneficially owned excludes (i) 1,214,228 shares issuable upon exercise of warrants held by Keystone, (ii) 12,195 shares issuable upon conversion of shares of preferred stock held by Keystone, at an alternate conversion price of $0.82, and (iii) 99,742,303 shares issuable pursuant to a common stock purchase agreement by and between the Company and Keystone, which in each case are subject to a prohibition on issuance if such issuance would result in the holder beneficially owning over 4.99% of the common stock.

SCHEDULE 13G

CUSIP Number(s): 68237Q401

1

Names of Reporting Persons

Fredric Zaino

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 223,717.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 223,717.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

223,717.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.1 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: The percentages used herein are calculated based upon 3,691,492 shares of common stock outstanding as of June 5, 2026, as reported by the Company in its Prospectus dated June 16, 2026 (Registration No. 333-296615), filed with the SEC on June 17, 2026. Amount beneficially owned excludes (i) 1,214,228 shares issuable upon exercise of warrants held by Keystone, (ii) 12,195 shares issuable upon conversion of shares of preferred stock held by Keystone, at an alternate conversion price of $0.82, and (iii) 99,742,303 shares issuable pursuant to a common stock purchase agreement by and between the Company and Keystone, which in each case are subject to a prohibition on issuance if such issuance would result in the holder beneficially owning over 4.99% of the common stock.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Onconetix, Inc.
(b)	Address of issuer's principal executive offices: 201 E. Fifth Street, Suite 1900, Cincinnati, Ohio 45202
Item 2.
(a)	Name of person filing: This statement is filed on behalf of the following persons with respect to shares of common stock of the Company acquired by them (the "Shares"): (i) Keystone Capital Partners, LLC, Delaware limited liability company ("Keystone"), with respect to Shares beneficially owned by it; (ii) RANZ Group LLC, a Delaware limited liability company ("RANZ Group"), with respect to Shares beneficially owned by it; and (iii) Fredric Zaino, an individual ("Mr. Zaino"), with respect to Shares beneficially owned by him. The foregoing persons are hereinafter referred to collectively as the "Reporting Persons." Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party. RANZ Group and Mr. Zaino do not own any Shares directly. Keystone is managed by RANZ Group. RANZ Group maintains investment and voting power with respect to the securities held or controlled by Keystone. Fredric Zaino, an individual, controls RANZ Group. By reason of the provisions of Rule 13d-3 of the Securities Exchange Act of 1934, as amended, RANZ Group and Mr. Zaino may be deemed to own beneficially all of the Shares (constituting approximately 6.1% of the shares outstanding). Each of RANZ Group and Mr. Zaino disclaim beneficial ownership of any of the securities covered by this statement, except to the extent of any pecuniary interest therein.
(b)	Address or principal business office or, if none, residence: 139 Fulton Street, Suite 412, New York, NY 10038
(c)	Citizenship: Keystone is a Delaware limited liability company. RANZ Group is a Delaware limited liability company. Mr. Zaino is a United States citizen.
(d)	Title of class of securities: Common stock, par value $0.00001 per share
(e)	CUSIP Number(s): 68237Q401
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: Keystone: 223,717 RANZ Group: 223,717 Mr. Zaino: 223,717
(b)	Percent of class: Keystone: 6.1% RANZ Group: 6.1% Mr. Zaino: 6.1%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Keystone: 0 RANZ Group: 0 Mr. Zaino: 0
	(ii) Shared power to vote or to direct the vote: Keystone: 223,717 RANZ Group: 223,717 Mr. Zaino: 223,717
	(iii) Sole power to dispose or to direct the disposition of: Keystone: 0 RANZ Group: 0 Mr. Zaino: 0
	(iv) Shared power to dispose or to direct the disposition of: Keystone: 223,717 RANZ Group: 223,717 Mr. Zaino: 223,717
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Keystone Capital Partners, LLC

Signature:	/s/ Fredric Zaino
Name/Title:	Fredric Zaino, as Managing Member of Keystone Capital Partners, LLC, as the CIO of Keystone Capital Partners, LLC
Date:	07/27/2026

RANZ Group LLC

Signature:	/s/ Fredric Zaino
Name/Title:	Fredric Zaino, as Managing Member of RANZ Group LLC
Date:	07/27/2026

Fredric Zaino

Signature:	/s/ Fredric Zaino
Name/Title:	Fredric Zaino, individually
Date:	07/27/2026

Exhibit Information

Exhibit 99.1 Joint Filing Agreement