Onconetix, Inc.

S-11 ea0263314-s1_onconetix.htm REGISTRATION STATEMENT

As filed with the Securities and Exchange Commission on November 4, 2025

Registration No. 333-

**UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-1

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

Onconetix, Inc.

(Exact Name of Registrant as Specified in its Charter)

**201 E. Fifth Street, Suite 1900

Telephone: (513) 620-4101

**(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

**Karina M. Fedasz

Interim Chief Executive Officer and Interim Chief Financial Officer

201 E. Fifth Street, Suite 1900

Telephone: (513) 620-4101

**(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service)

with copies to:

**Barry I. Grossman, Esq.

Jessica Yuan, Esq.

Ellenoff Grossman & Schole LLP

1345 Avenue of the Americas

New York, NY 10105

Phone: (212) 370-1300

Fax: (212) 370-7889

**Approximate date of commencement of proposed sale to the public:**From time to time after this registration statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.☐

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. The Selling Stockholders named in this prospectus may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and we are not soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted.

22,071,891 Shares of Common Stock

This prospectus relates to the resale by Selling Stockholders of 22,071,891 shares of common stock of Onconetix, Inc. (“we,” “us,” “our,” the “Company,” or “Onconetix”), par value $0.00001 per share (the “Common Stock”), by the Selling Stockholders listed in this prospectus or their permitted transferees (the “Selling Stockholders”). The shares of Common Stock registered for resale pursuant to this prospectus include:

The Series D Warrant has an initial exercise price of $3.6896 and the Series E Warrant has an initial exercise price of $3.8576, subject to adjustment, and will expire three years from the issuance date. The conversion price of the Series D Preferred Stock is $3.6896 and the conversion price of the Series E Preferred Stock is $3.8576, subject to adjustment as provided in their respective Certificates of Designations.

We are registering the above-referenced shares on behalf of the Selling Stockholders, to be offered and sold by them from time to time. We are not selling any securities under this prospectus. We will receive the proceeds from any exercise of the PIPE Warrants for cash, but not from the net exercise of any PIPE Warrants on a cashless basis or from the resale of any shares of Common Stock by the Selling Stockholders pursuant to this prospectus or the sale of the shares of Common Stock issuable upon the exercise of the PIPE Warrants.

Our Common Stock is listed on The Nasdaq Capital Market under the symbol “ONCO.” The last reported sale price of our Common Stock on The Nasdaq Capital Market on November 3, 2025 was $3.16 per share. We recommend that you obtain current market quotations for our Common Stock prior to making an investment decision.

The Selling Stockholders may offer all or part of the shares for resale from time to time through public or private transactions, at either prevailing market prices or at privately negotiated prices. Our registration of the shares of Common Stock covered by this prospectus does not mean that the Selling Stockholders will offer or sell any of the shares. With regard only to the shares the Selling Stockholders sell for their own behalf, the Selling Stockholders may be deemed an “underwriter” within the meaning of the Securities Act of 1933, as amended (the “Securities Act”). The Company has paid all of the registration expenses incurred in connection with the registration of the shares. We will not pay any of the selling commissions, brokerage fees and related expenses.

We will pay the expenses incurred in registering the shares, including legal and accounting fees. See “Plan of Distribution” on page 30 of this prospectus.

Investing in our Common Stock involves certain risks. See “Risk Factors” on page 6 of this prospectus, included in any accompanying prospectus supplement and in the documents incorporated by reference in this prospectus for a discussion of the factors you should carefully consider before deciding to purchase these securities.

We may amend or supplement this prospectus from time to time by filing amendments or supplements as required. We urge you to read the entire prospectus, any amendments or supplements, any free writing prospectuses, and any documents incorporated by reference carefully before you make your investment decision.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is , 2025

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