Onconetix, Inc.

S-11 ea0301584-s1_onconetix.htm REGISTRATION STATEMENT

As filed with the Securities and Exchange Commission on August 11, 2026

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)

**David A. White

Chief Executive 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:

**Dennis O’Rourke, Esq.

Brian Daughney, Esq.

Moritt Hock & Hamroff LLP

400 Garden City Plaza, 2nd Floor

Garden City, NY 11530

Phone: (516) 873-2000

**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 Stockholder 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.

100,000,000 Shares of Common Stock

This prospectus relates to the resale by the Selling Stockholders of up to 100,000,000 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 consist of up to 100,000,000 shares of Common Stock. Assuming all 100,000,000 shares of Common Stock were issued, this would represent 2,532% of the aggregate number of shares of Common Stock outstanding as of August 10, 2026. The shares registered hereby are issuable only upon conversion of a portion of the 37,812 shares of Series F preferred stock (the “Series F Preferred Stock”) issued to investors in a private placement transaction that closed on July 29, 2026 and are subject to the limitations contained in the Series F Certificate of Designations, including the Nasdaq Exchange Cap (until stockholder approval is obtained) and the applicable beneficial ownership limitations. As a result of these conversion limitations, we currently could only issue 789,426 shares of Common Stock upon conversion of the Series F Preferred Stock. We are registering for resale by the Selling Stockholders up to 100,000,000 shares of Common Stock issuable upon conversion of a portion of the Series F Preferred Stock.

The Series F Preferred Stock is convertible into shares of Common Stock at an initial conversion price of $0.9767 per share, subject to adjustment as provided in the Series F Certificate of Designations which is filed as an Exhibit of the registration statement of which this prospectus forms a part.

We are registering the above-referenced shares of Common Stock 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 not receive any proceeds from the sale of any shares of Common Stock by the Selling Stockholders pursuant to this prospectus.

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 August 11, 2026 was $0.9682 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. The Company will pay 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 48 of this prospectus.

Investing in our Common Stock involves certain risks. See “Risk Factors” on page 12 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 [●]

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