Onconetix (ONCO) registers 3.7M shares for resale by selling stockholder; company receives no proceeds

The last reported sale price of our Common Stock on The Nasdaq Capital Market on June 5, 2026 was $1.03 per share.

The offering price of our Common Stock to be sold by the Selling Stockholder does not necessarily bear any relationship to our book value, assets, past operating results, financial condition, or any other established criteria of value.

To the extent that the Company sells shares of Common Stock under the ELOC Purchase Agreement, substantial amounts of shares could be issued and resold, which would cause dilution and may impact the Company's stock price.

We believe that our current cash balance is not sufficient to fund its operations for one year from the date of issuance of the consolidated financial statements for the year. While such capital raises may enable us to sustain current operations and meet existing obligations, we continue to generate recurring net operating losses and have not yet established sustained positive cash flows to support our strategic growth initiatives. Such initiatives include the commercialization of Proclarix and our development and commercialization of future product candidates. These factors raise substantial doubt on our ability to continue as a going concern for one year from the date of issuance of our consolidated financial statements for the financial year ended December 31, 2025 and March 31, 2026.

As of March 31, 2026, we had cash of approximately $3.7 million, working capital of approximately $1.3 million and an accumulated deficit of approximately $135.4 million. During the quarter ended March 31, 2026, we used approximately $2.1 million in cash for operating activities. In addition, as of June 5, 2026, our cash balance was approximately $6.5 million.

On February 11, 2026, we entered into a Share Exchange Agreement (the “Share Exchange Agreement”), by and among (i) Onconetix, (ii) Realbotix Corp., a company existing under the laws of the Province of Ontario (“Parent”), (iii) Simulacra Corporation, a Delaware corporation and a wholly-owned subsidiary of Parent (the “Seller”) and (iv) Realbotix, LLC, a Delaware limited liability company and wholly owned subsidiary of the Seller (the “Realbotix”).

Pursuant to the Share Exchange Agreement, subject to the terms and conditions set forth therein, the Seller agreed to contribute and transfer to us, and we agreed to acquire and accept, all of the issued and outstanding equity interests of Realbotix (the “Realbotix Interests”) in exchange for newly issued shares of Common Stock.

However, in light of (i) the time and resources needed to continue pursuing commercialization of ENTADFI, and (ii) the Company’s cash runway and indebtedness, the Company abandoned commercialization of ENTADFI and no longer holds remaining inventory of the product as of December 31, 2025. In addition, as part of cost reduction efforts and in connection with our initial pause in commercializing ENTADFI, we terminated three employees involved with the ENTADFI program, effective April 30, 2024, with such individuals to continue assisting the Company on an as-needed, consulting basis. Based on the circumstances surrounding ENTADFI, at June 30, 2024, the ENTADFI assets were fully impaired.

On May 21, 2026, the Company effected a reverse stock split of all shares of its issued and outstanding Common Stock at a ratio of one-for-ten (1:10). The Company accounted for the reverse stock split on a retrospective basis pursuant to Accounting Standards Codification (“ASC”) 260, Earnings Per Share. All issued and outstanding common stock, common stock warrants, and share-based awards’ exercise prices and per share data have been adjusted in these condensed consolidated financial statements, on a retrospective basis, to reflect the reverse stock split for all periods presented.

We are not selling any securities under this prospectus and will not receive any proceeds from the sale of Common Stock by the Selling Stockholder pursuant to this prospectus.

We may receive up to $25 million in aggregate gross proceeds from Keystone under the ELOC Purchase Agreement in connection with sales of the shares of our Common Stock pursuant to the ELOC Purchase Agreement after the date of this prospectus.

Through June 5, 2026, the Company has sold approximately 2.6 million split-adjusted shares under the ELOC Purchase Agreement for aggregate proceeds of approximately $11.3 million.

Pursuant to the ELOC Purchase Agreement, 30% of the gross proceeds to the Company from any sale of Common Stock thereunder must be applied towards the redemption of the Company’s Series C Preferred Stock.

These factors raise substantial doubt on our ability to continue as a going concern for one year from the date of issuance of our consolidated financial statements for the financial year ended December 31, 2025 and March 31, 2026.

As of March 31, 2026, we had cash of approximately $3.7 million, working capital of approximately $1.3 million and an accumulated deficit of approximately $135.4 million. In addition, as of June 5, 2026, our cash balance was approximately $6.5 million.

In particular, the development and commercialization of Proclarix in the United States is being pursued by Labcorp, pursuant to an exclusive license agreement that grants Labcorp the exclusive right to develop and commercialize Proclarix, and other products developed by Labcorp using Proteomedix’s intellectual property covered by the license, in the United States for identification, screening, staging, predisposition, diagnosis, prognosis, monitoring, prevention or treatment selection with respect to prostate cancer. However, we do not have control over Labcorp’s development and commercialization of Proclarix, and there can be no guarantee that Labcorp will continue to advance development and commercialization efforts, or that Labcorp will successfully commercialize Proclarix in the United States.

As provided in Nasdaq Listing Rule 5550(a) (2), companies listed on Nasdaq are required Capital Market to maintain a minimum bid price of $1.00 per share (the “Bid Price Rule”).

There are no assurances that the Panel will grant the Company’s request for continued listing or an extension to demonstrate compliance. If the Company does not obtain a favorable decision from the Panel, its Common Stock will become subject to delisting.

Our net loss was $14.0 million and $58.7 million for the years ended December 31, 2025 and 2024, respectively. As of December 31, 2025, we had an accumulated deficit of $131.2 million. We also generated negative operating cash flows of $9.7 million for the year ended December 31, 2025.

the Company may not issue or sell any shares of Common Stock to Keystone under the Common Stock Purchase Agreement which, when aggregated with all other shares of Common Stock then beneficially owned by Keystone and its affiliates (as calculated pursuant to Section 13(d) of the Securities Exchange Act of 1934, as amended, and Rule 13d-3 promulgated thereunder), would result in Keystone beneficially owning more than 4.99% of the outstanding shares of Common Stock (the “ELOC Blocker”).

at a purchase price equal to the lesser of 90% of (i) the daily volume weighted average price (the “VWAP”) of the Common Stock for the five trading days immediately preceding the applicable Purchase Date for such Fixed Purchase and (ii) the lowest sale price of a share of Common Stock on the applicable Purchase Date for such Fixed Purchase during the full trading day on such applicable Purchase Date. ... Pursuant to the ELOC Purchase Agreement, up to 30% of the proceeds from each Fixed Purchase and VWAP Purchase Notice must be used to redeem shares of Series C Preferred Stock.

As of June 5, 2026, there were 3,691,492 shares of Common Stock outstanding. If all of the 100,000,000 shares of our Common Stock offered for resale by the Selling Stockholders under this prospectus were issued and outstanding as of June 5, 2026, such shares would represent approximately 96.4% of the total number of shares of our Common Stock outstanding.

Keystone Capital Partners, LLC(2) | * | * | 100,000,000 | * | 4.99 %(3)

KCP Fund I, LLC | * | * | 100,000,000 | * | 4.99 %(3)

Under the terms of the ELOC Purchase Agreement, the Company may not issue shares to the Selling Stockholder under the ELOC Purchase Agreement to the extent that such issuance would cause the Selling Stockholder, together with its affiliates and attribution parties, to beneficially own a number of shares of Common Stock which would exceed 4.99% of our then outstanding Common Stock following such issuance

Keystone Capital Partners LLC is managed by RANZ Group LLC. Frederic Zaino, the Managing Member of RANZ Group LLC, may be deemed to have investment discretion and voting power over the shares held by Keystone Capital Partners LLC.

which contains an explanatory paragraph regarding the Company’s ability to continue as a going concern