Onconetix, Inc.

Note 1 — Organization and Basis of Presentation

Organization and Nature of Operations

Onconetix, Inc. (formerly known as Blue Water Biotech, Inc. and Blue Water Vaccines Inc.) (the “Company” or “Onconetix”) was formed on October 26, 2018, and is a commercial stage biotechnology company focused on the research, development, and commercialization of innovative solutions for oncology.

On December 15, 2023, Onconetix acquired 100% of the issued and outstanding voting equity interests in Proteomedix AG, a Swiss company (“Proteomedix” or “PMX”), and its related diagnostic product Proclarix. As a result of this transaction, Proteomedix became a wholly owned subsidiary of Onconetix. Proteomedix is a healthcare company whose mission is to transform prostate cancer diagnosis. Proteomedix has identified novel biomarker signatures with utility in prostate cancer diagnosis, prognosis and therapy management.

In April 2023, the Company acquired ENTADFI, a Food and Drug Administration (“FDA”)-approved, once daily pill that combines finasteride and tadalafil for the treatment of benign prostatic hyperplasia.

Historically, the Company’s focus was on the research and development of transformational vaccines to prevent infectious diseases worldwide, until the third quarter of 2023, at which time the Company halted its efforts on vaccine development activities to focus on commercialization activities for ENTADFI and pursue other potential acquisitions. 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 the ENTADFI assets were fully impaired at June 30, 2024 (see Notes 4 and 5).

On April 21, 2023, the Company filed an amendment to its Amended and Restated Certificate of Incorporation with the Secretary of State of Delaware to change its corporate name from “Blue Water Vaccines Inc.” to “Blue Water Biotech, Inc.” The name change was effective as of April 21, 2023. On December 15, 2023, the Company filed an amendment to its Amended and Restated Certificate of Incorporation with the Secretary of State of Delaware to change its corporate name from “Blue Water Biotech, Inc.” to “Onconetix, Inc.” In connection with each of the name changes, the Company also amended the Company’s bylaws to reflect the new corporate name.

Reverse Stock Split

On March 25, 2026, the Company effected a reverse stock split of all shares of its issued and outstanding Common Stock at a ratio of one-for-five (1:5). The Company accounted for the reverse stock split on a retrospective basis pursuant to 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 consolidated financial statements, on a retrospective basis, to reflect the reverse stock split for all periods presented. The number of authorized shares and par value of the preferred stock and common stock were not adjusted because of the reverse stock split.

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 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 consolidated financial statements, on a retrospective basis, to reflect the reverse stock split for all periods presented. The number of authorized shares and par value of the preferred stock and common stock were not adjusted because of the reverse stock split.

Note 1 — Organization and Basis of Presentation (cont.)

Basis of Presentation and Principles of Consolidation

The Company’s condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the accounts of Onconetix and its 100% wholly owned subsidiary, Proteomedix, since the acquisition date of December 15, 2023. All significant intercompany balances and transactions have been eliminated in consolidation.

Unaudited Interim Consolidated Financial Statements

The accompanying condensed consolidated balance sheet as of June 30, 2026, and the condensed consolidated statements of operations and comprehensive loss and the condensed consolidated statements of convertible preferred stock and stockholders’ equity (deficit) for the three and six months ended June 30, 2026 and 2025, and the condensed consolidated statements of cash flows for the six months ended June 30, 2026 and 2025 are unaudited. These unaudited interim consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements, and in management’s opinion, include all adjustments, consisting of only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of June 30, 2026 and its results of operations and comprehensive loss for the three and six months ended June 30, 2026 and 2025, and its cash flows for the six months ended June 30, 2026 and 2025. The financial data and the other financial information disclosed in the notes to these condensed consolidated financial statements related to the three-month periods are also unaudited. Operating results for the three and six months ended June 30, 2026, are not necessarily indicative of the results that may be expected for the year ended December 31, 2026, any other interim periods, or any future year or period. The unaudited condensed consolidated financial statements included in this Report should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025, which includes a broader discussion of the Company’s business and the risks inherent therein.

Note 2 — Going Concern and Management’s Plans

The Company’s operating activities to date have been devoted to seeking licenses, engaging in research and development activities, potential asset and business acquisitions, expenditures associated with the previously planned commercial launch of ENTADFI, and the commercialization of Proclarix.

The Company has incurred substantial operating losses since inception and expects to continue to incur significant operating losses for the foreseeable future.

As of June 30, 2026, the Company had cash of approximately $5.9 million, a working capital surplus of approximately $3.6 million and an accumulated deficit of approximately $138.3 million. During the six months ended June 30, 2026, the Company used approximately $4.0 million in cash for operating activities. In addition, as of August 10, 2026, the Company’s cash balance was approximately $5.4 million.

The Company continues to generate recurring net operating losses and has not yet established sustained positive cash flows to support its strategic growth initiatives, which includes the commercialization of Proclarix, and participation in strategic transactions and investments, including its proposed acquisition of Realbotix. These factors raise substantial doubt about the Company’s ability to continue as a going concern within one year from the date of the issuance of these consolidated financial statements.

Management’s plans for funding the Company’s operations include advancing its strategic initiatives, including commercialization efforts related to Proclarix, and execution of recent and potential strategic transactions. Subsequent to June 30, 2026, on July 28, 2026, the Company entered into a securities purchase agreement pursuant to which it issued Series F Preferred Stock for aggregate gross proceeds of approximately $30.2 million and received net cash proceeds of approximately $0.25 million. Management has considered the impact of this financing, together with its ongoing efforts to obtain additional capital and improve operating cash flows, in evaluating the Company's ability to continue as a going concern. While the transaction provided additional liquidity, management believes that the Company will continue to require additional financing and/or improved operating results to fund its operations and satisfy its obligations as they become due.

Management also intends to pursue additional equity or debt financing to support operations and strategic initiatives. However, there are currently no committed sources of financing, and there is no assurance that additional funding will be available on favorable terms, if at all. This uncertainty raises significant concern about the Company’s ability to sustain operations and execute its strategic initiatives. If additional capital is not secured, the Company may need to curtail clinical trials, development, and commercialization efforts, and take further measures to reduce expenses to conserve cash.

Because of historical and expected operating losses and net operating cash flow deficits, there is substantial doubt about the Company’s ability to continue as a going concern for one year from the issuance of the unaudited condensed consolidated financial statements, which is not alleviated by management’s plans. The unaudited condensed consolidated financial statements have been prepared under the going concern basis of accounting. These unaudited condensed consolidated financial statements do not include any adjustments that might be necessary from the outcome of this uncertainty.

Note 3 — Summary of Significant Accounting Policies

During the six months ended June 30, 2026, there were no changes to the Company’s significant accounting policies described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025. Selected significant accounting policies are discussed in further detail below:

Fair Value Measurements

Fair value is defined as the price that would be received for sale of an asset or paid for transfer of a liability, in an orderly transaction between market participants at the measurement date. U.S. GAAP establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). These tiers include:

In some circumstances, the inputs used to measure fair value might be categorized within different levels of the fair value hierarchy. In those instances, the fair value measurement is categorized in its entirety in the fair value hierarchy based on the lowest level input that is significant to the fair value measurement. Financial instruments, including cash, inventory, accounts receivable, accounts payable, accrued liabilities, operating lease liabilities, and notes payable are carried at cost, which management believes approximates fair value due to the short-term nature of these instruments.

The fair value of the contingent warrant liability and Series D and E derivative liabilities are valued using significant unobservable measures and other fair value inputs and are therefore classified as Level 3 financial instruments.

Note 3 — Summary of Significant Accounting Policies(cont.)

The fair value of financial instruments measured on a recurring basis is as follows as of June 30, 2026 and December 31, 2025:

These non-financial assets had been valued using significant unobservable measures and other fair value inputs and were classified as Level 3 measurements.

None of the Company’s other non-financial assets or liabilities are recorded at fair value on a non-recurring basis as of June 30, 2026 and December 31, 2025. There were no transfers between levels during the periods presented.

New Accounting Pronouncements

There were no new accounting pronouncements issued since the Company’s filing of the Annual Report on Form 10-K for the year ended December 31, 2025, which could have a significant effect on the accompanying condensed consolidated financial statements.

Note 4 — Balance Sheet Details

Inventories

Inventories, which primarily relate to Proclarix product as of June 30, 2026 and December 31, 2025, consisted of the following:

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following as of June 30, 2026, and December 31, 2025:

Goodwill

Goodwill consisted of the following as of June 30, 2026 and December 31, 2025:

Note 4 — Balance Sheet Details(cont.)

Impairments for three and six months ended June 30, 2026 and 2025

During the three and six months ended June 30, 2026 and 2025, the Company’s stock price and market capitalization declined, and the Company determined that this was an indicator of a potential impairment of its goodwill. Accordingly, as of June 30, 2026 and 2025, the Company performed quantitative analysis to identify and measure the amount of impairment losses to be recognized. The Company recognized goodwill impairment losses of approximately $0.5 million and $0.6 million for the three months ended June 30, 2026 and 2025, respectively. The Company recognized goodwill impairment losses of approximately $8.6 million and $11.5 million for the six months ended June 30, 2026 and 2025, respectively.

The fair value of the reporting unit is estimated using a market approach. Beginning in the second quarter of 2024, the Company elected to use a market capitalization reconciliation methodology as its sole valuation technique in estimating the fair value of the reporting unit. Under this approach, the fair value of the reporting unit is determined based on the Company's market capitalization, calculated using the quoted market price of its common stock and outstanding shares, with consideration given to whether adjustments are necessary to reconcile market capitalization to the fair value of the reporting unit.

Accrued Expenses

Accrued expenses consisted of the following as of June 30, 2026 and December 31, 2025:

Note 5 — Significant Agreements

Immunovia AB

On September 17, 2025, Proteomedix entered into a license agreement with Immunovia AB, pursuant to which Immunovia obtained exclusive rights to certain intellectual property and proprietary biological materials related to the PancreaSure™ test. In exchange for these rights, Immunovia paid Proteomedix a non-refundable upfront license fee of $0.3 million. Based on the terms of the agreement and the nature of the license, the Company determined that the performance obligations were satisfied upon the transfer of the licensed rights. Accordingly, the Company recognized the $0.6 million as license revenue during the year ended December 31, 2025. Additionally, the agreement provided for a second payment of $0.3 million due by March 31, 2026, which was received during the six months ended June 30, 2026, and is no longer shown as a part of Accounts receivable, net on the consolidated balance sheet as of June 30, 2026.

Notes 6 — Notes Payable

Insurance Financing

During the six months ended June 30, 2026, the Company obtained financing for certain Director & Officer liability insurance policy premiums. The agreement assigns the lender a first priority lien on and security interest in the financed policies and any additional premium required in the financed policies.

The total premiums, taxes and fees financed are approximately $0.3 million, with an annual interest rate of 8.5%. In consideration of the premium payment by the lender to the insurance companies or the agent or broker, the Company unconditionally promised to pay the lender the amount financed plus interest and other charges permitted under the agreement. At June 30, 2026, the Company recognized approximately $0.15 million as an insurance financing note payable, which is included in the current portion of notes payable in the accompanying condensed consolidated balance sheets. The Company will pay the insurance financing through monthly installment payments of approximately $25,693, with the last payment for the note due on December 17, 2026.

Note 7 — Subscription Agreement

On December 18, 2023, the Company entered into a subscription agreement (the “Subscription Agreement”) with the PMX Investor, who became a stockholder of Onconetix at the closing of the PMX Transaction, for the sale of 118 units, each comprised of 1 share of common stock and 0.30 pre-funded warrants (the “Units”) at $42,500 per Unit. The Subscription Agreement includes a make-whole provision (the “Make-Whole Provision”) which requires the issuance of additional shares of common stock in the event that the 270-day volume weighted average price after the closing of the Subscription Agreement, is below $42,500, and the PMX Investor still holds the common shares acquired upon closing of the Subscription Agreement 270 days after such closing. The Subscription Agreement would only close upon obtaining stockholder approval for certain transactions involving the Company’s Series B Preferred Stock. The Subscription Agreement was amended on January 23, 2024 to include a provision for interest on the $5 million debenture, accruing at a rate of 4%, to be included in the calculation of the units to be issued upon the conversion. Stockholder approval was obtained on September 5, 2024, and as a result, the conversion and the issuance of 118 units, attributable to the Subscription Agreement, and 3 units, attributable to additional accrued interest under the debenture to the PMX Investor took place on September 24, 2024.

As of June 30, 2026 and December 31, 2025, the fair value of the related party subscription agreement liability was $0. For the three and six months ended June 30, 2025, the Company recognized a change in fair value of the related party subscription agreement liability of approximately $191,000 and $3,128,000. No gain or loss related to changes in the fair value of the related party subscription liability was recognized during the three and six months ended June 30, 2026, as the liability was settled in the prior year.

Note 8 — Warrant and derivative liabilities

Contingent warrant liabilities

The following table summarizes the activity for the contingent warrant liabilities, using unobservable Level 3 inputs, for the three and six months ended June 30, 2026:

Series D derivative liabilities and warrant liabilities

On September 22, 2025, the Company completed a private placement transaction with institutional investors, resulting in the issuance of Series D convertible preferred stock and accompanying warrants to purchase shares of common stock. In connection with the Series D PIPE Financing, the Company recorded warrant liabilities related to the Series D Warrants and derivative liabilities associated with certain embedded features in the Series D Preferred Stock. These instruments were classified as liabilities and measured at fair value in accordance with ASC 815 due to their settlement provisions and other contractual terms. Refer to Note 9 for further details on the private placement transaction.

The Company measured its bifurcated embedded derivative liabilities and warrant liabilities as of June 30, 2026, December 31, 2025 and September 22, 2025, at fair value on a recurring basis using level 3 inputs. These financial instruments are measured using management’s best estimate of fair value, where the inputs into the determination of fair value require significant management judgment and estimation. The derivative liabilities and warrant liabilities were both measured using Monte Carlo valuation models. Valuations based on unobservable inputs are highly subjective and require significant judgments. Changes in such judgments could have a material impact on fair value estimates.

As of December 11, 2025, the Company had entered a letter of intent with Realbotix (“LOI”), which contemplates a change of control transaction. A closing condition of the LOI is that no convertible securities of the Company will be outstanding prior to, or upon, closing (subject to approval of the preferred shareholders) which creates two distinct timing scenarios for the settlement of the preferred securities: prior to, or at closing, pursuant to the terms of the LOI or after closing in the event the transaction proposed by the LOI is not completed. Given the disparate timing conditions, the valuation included two scenarios in the Monte Carlo valuation analysis as of December 31, 2025: Closing and No Closing. The Closing scenario includes settlement logic for the preferred securities based on the profit-maximizing outcome of the preferred shareholder at the hypothetical closing date. The No Closing scenario models the embedded derivatives as if there was no forced conversion event (similar to valuation analyses of the embedded derivatives as of their original issuance and September 30, 2025).

As of June 30, 2026, the Company refined its valuation technique for the No Closing Scenario to explicitly incorporate the probability that the Company will have sufficient funding to continue operations over the applicable term. This refinement considers the Company’s cash position, projected operating cash requirements, and its ability to access remaining capacity under its equity line of credit facility and reflects the increasing significance of these funding considerations as the Company’s cash position and available financing alternatives have evolved.

The table below shows the inputs used to determine the fair value of the derivative liabilities:

The Limited Waiver Agreement executed on December 23, 2025 resulted in reclassification of the warrants to equity, the warrant liability was remeasured using inputs as of December 23, 2025, and no subsequent liability remeasurement was required through December 31, 2025.

Note 8 — Warrant and derivative liabilities(cont.)

The following table presents information about the Company’s derivative liabilities that are measured at fair value on a recurring basis as of June 30, 2026 and December 31, 2025, and indicates the fair value hierarchy of the valuation inputs the Company utilized to determine such fair value:

The following table sets forth a summary of the change in the fair value of the derivative liabilities that are measured at fair value on a recurring basis for the six months ended June 30, 2026:

Series E derivative liabilities and warrant liabilities

On October 1, 2025, the Company completed a private placement transaction with institutional investors, resulting in the issuance of Series E convertible preferred stock and accompanying warrants to purchase shares of common stock. In connection with the Series E PIPE financing, the Company recorded warrant liabilities related to the Series E Warrants and derivative liabilities associated with certain embedded features in the Series E Preferred Stock. These instruments were classified as liabilities and measured at fair value in accordance with ASC 815 due to their settlement provisions and other contractual terms. Refer to Note 9 for further detail on the private placement transaction.

The Company measures its bifurcated embedded derivative liability and warrant liability as of June 30, 2026, December 31, 2025 and issuance, at fair value on a recurring basis using level 3 inputs. These financial instruments are measured using management’s best estimate of fair value, where the inputs into the determination of fair value require significant management judgment to estimation. The derivative liability and warrant liability were both measured using Monte Carlo valuation models. Valuations based on unobservable inputs are highly subjective and require significant judgments. Changes in such judgments could have a material impact on fair value estimates.

As of December 11, 2025, the Company had entered a letter of intent with Realbotix (“LOI”), which contemplates a change of control transaction. A closing condition of the LOI is that no convertible securities of the Company will be outstanding prior to, or upon, closing (subject to approval of the preferred shareholders) which creates two distinct timing scenarios for the settlement of the preferred securities: prior to, or at closing, pursuant to the terms of the LOI or after closing in the event the transaction proposed by the LOI is not completed. Given the disparate timing conditions, the valuation included two scenarios in the Monte Carlo valuation analysis as of June 30, 2026 and December 31, 2025: Closing and No Closing. The Closing scenario includes settlement logic for the preferred securities based on the profit-maximizing outcome of the preferred shareholder at the hypothetical closing date. The No Closing scenario models the embedded derivatives as if there was no forced conversion event (similar to valuation analyses of the embedded derivatives as of their original issuance and September 30, 2025).

Note 8 — Warrant and derivative liabilities (cont.)

The table below shows the inputs used to determine the fair value of the derivative liabilities:

The Limited Waiver Agreement executed on December 23, 2025 resulted in reclassification of the warrants to equity, the warrant liability was remeasured using inputs as of December 23, 2025, and no subsequent liability remeasurement was required through December 31, 2025.

The following table presents information about the Company’s derivative liabilities that are measured at fair value on a recurring basis as of June 30, 2026 and December 31, 2025, and indicates the fair value hierarchy of the valuation inputs the Company utilized to determine such fair value:

The following table sets forth a summary of the change in the fair value of the derivative liabilities that are measured at fair value on a recurring basis for the six months ended June 30, 2026:

Note 9 — Convertible Preferred Stock and Stockholders’ Equity

Authorized Capital

As of June 30, 2026 and December 31, 2025, the Company is authorized to issue 250,000,000 shares and 10,000,000 shares of common stock and preferred stock, respectively, with a par value of $0.00001 for both common stock and preferred stock.

At June 30, 2026 and December 31, 2025, the Company had designated 1,150,000 shares,10,000 shares,2,700,000 shares,10,000 shares,32,000 shares, and 10,000 shares of Series Seed Preferred Stock, Series A Preferred Stock, Series B Preferred Stock, Series C Preferred Stock, Series D Preferred Stock, and Series E Preferred Stock, respectively.

Note 9 — Convertible Preferred Stock and Stockholders’ Equity (cont.)

Preferred Stock

Series Seed Convertible Preferred Stock

The Company has 1,150,000 shares of preferred stock designated as Series Seed Preferred Stock (“Series Seed”) and there areno shares of Series Seed outstanding as of June 30, 2026 and December 31, 2025.

Series A Convertible Preferred Stock

On September 29, 2023, the Company filed a Certificate of Designations of Rights and Preferences of Series A Preferred Stock of the Company (the “Series A Certificate of Designations”) with the State of Delaware to designate and authorize the issuance of up to 10,000 shares of Series A Preferred Stock.

On October 3, 2023, the Company issued 3,000 shares of Series A Convertible Preferred Stock in exchange for the settlement of $3.0 million in notes payable due to Veru, Inc.

On September 24, 2024, Veru converted all 3,000 shares of Series A Convertible Preferred Stock into 33 shares of the Company’s common stock per the stated conversion ratio. There were 0 shares of Series A Convertible Stock outstanding as of June 30, 2026 and December 31, 2025.

Series B Convertible Preferred Stock

In connection with the PMX acquisition on December 15, 2023, the Company issued 2,696,729 shares of Series B Convertible Preferred Stock, which were initially convertible into approximately 1,586 shares of common stock, subject to stockholder approval on September 5, 2024. All Series B Preferred Stock was fully converted into common stock on September 24, 2024. As of June 30, 2026 and December 31, 2025, no Series B Preferred Stock remains outstanding.

Series C Convertible Preferred Stock

On October 1, 2024, the Board of Directors authorized the Company to create a series of 10,000 shares of preferred stock designated as “Series C Convertible Preferred Stock”, with a par value of $0.00001, pursuant to the certificate of designations. At any time after the initial issuance date of Series C convertible Preferred Stock, each Preferred Share shall be convertible into validly issued, fully paid and non-assessable shares of Common Stock. The holders of Series C Preferred Stock are entitled to dividends, on an as-if converted basis, equal to and in the same form as dividends actually paid on shares of Common Stock, when and if actually paid. In addition, from and after the occurrence and during the continuance of any Triggering Event, dividends (“Default Dividends”) will accrue on the Stated Value of each Preferred Share at a rate of fifteen percent (15.0%) (the “Default Rate”) per annum. Each holder is entitled to convert any portion of the outstanding Preferred Shares held by such holder into validly issued, fully paid and non-assessable Conversion shares at the Conversion Rate, which can be determined by dividing (x) the Conversion Amount of such Preferred Share by (y) the Conversion Price, $225.28, subject to adjustment as provided in the Certificate of Designations.

On July 16, 2025, the Company exercised its voluntary Series C Preferred Stock adjustment right to lower the conversion price of the Series C Preferred Stock to $175, and holders of 1,920 shares of Series C Preferred Stock agreed to convert their shares into shares of Common Stock. During the year ended December 31, 2025,1,369 shares of Series C Preferred Stock were redeemed for an aggregate amount of $1.71 million,1,920 shares of Series C Preferred Stock were converted into common stock and 203 shares of Series C Preferred Stock were exchanged into 244 shares of Series D Preferred Stock (as defined below). As of June 30, 2026 and December 31, 2025,7 shares of Series C Preferred Stock remain outstanding, with a carrying value of $1.7 thousand, as reflected in the accompanying consolidated balance sheet.

Series D Preferred Stock

On September 22, 2025, the Company entered into a securities purchase agreement (the “Series D Securities Purchase Agreement” and the financing contemplated therein, the “Series D PIPE Financing”) with eleven institutional investors, and sold or exchanged debt, to such investors (collectively, the “Series D PIPE Investors”) an aggregate of 16,099 shares of Series D convertible preferred stock, par value $0.00001 per share (“Series D Preferred Stock”), which includes an issuance of 500 shares of Series D Preferred Stock to the lead investor in consideration for the Series D PIPE Investors’ irrevocable commitment to purchase shares of the Series D Preferred Stock, and warrants (the “Series D Warrants”) to purchase 872,567 shares of Common Stock, (the Series D Preferred Stock together with the Series D Warrants, the “Series D PIPE Securities”), for an aggregate purchase price of approximately $12.9 million and net cash proceeds of $9.3 million. The exercise price of the Series D Warrants is $0.9716, and the Series D Warrants are exercisable beginning on the issuance date and expire on the third anniversary of the issuance date.

The Series D Preferred Stock was determined to be more akin to an equity-like host than a debt-like host and was classified as permanent equity as it was not redeemable in any manner that would require classification outside of permanent equity pursuant to ASC 480-10-S99. The Series D Preferred Stock was recorded on the accompanying consolidated balance sheet at its par value. Certain embedded share-settled redemption features within the Series D Preferred Stock were bifurcated and accounted for separately a derivative liability.

The Series D Warrants and certain embedded share-settled redemption features of the Series D Preferred Stock issued were determined to be liability-classified instruments pursuant to ASC 480 and ASC 815. The embedded features of the Series D Preferred Stock were bifurcated and accounted for separately as derivative liabilities. The Company measured the warrant liabilities and bifurcated derivative liabilities at fair value on a recurring basis using Level 3 inputs as of September 22, 2025 (the issuance date), December 23, 2025 (amended warrants date), December 31, 2025 (derivative liabilities fair value date) and June 30, 2026, respectively. See Note 8 for further information regarding the valuation methodology and assumptions used in determining the fair value of the warrant and derivative liabilities.

The Series D Preferred Stock hasno voting rights. The Series D Preferred Stock are convertible into common stock at the election of the holders of the Series D Preferred Stock at any time at an initial conversion price of $184.45 per share. The conversion price is subject to customary adjustments for stock dividends, stock splits, reclassifications, stock combinations and the like (subject to certain exceptions), anti-dilution provisions, and a floor price of $0.5322.

The Series D Preferred Stock is not redeemable by the holder except in the event of 1) a liquidation, dissolution, or winding up, or 2) the Series D Preferred Stock is redeemable for common stock of the Company upon the occurrence of a change in control. Holders of the Series D Preferred Stock shall be entitled to receive dividends as authorized and declared by the Company’s Board of Directors, payable in cash, securities, or in other assets as determined by the Company’s Board of Directors.

In the event of the Company’s liquidation, dissolution, or winding up, holders of the Series D Preferred Stock will be entitled to receive out of the assets, whether capital or surplus, an amount equal to the stated value of the Series D Preferred Stock, plus any accrued and unpaid dividends thereon and any other fees or liquidated damages owed before any distribution or payment shall be made to the holders of any junior securities.

During the six months ended June 30, 2026, holders of Series D Preferred Stock converted 8,169 shares into 375,977 shares of common stock. As of June 30, 2026 and December 31, 2025,8,156 and 16,325 shares of Series D Preferred Stock remain outstanding, respectively.

Series E Preferred Stock

On October 1, 2025, Onconetix entered into, and sold to institutional investor(s) (collectively, the “PIPE Investors”), pursuant to a securities purchase agreement (the “Securities Purchase Agreement”) an aggregate of 7,813 shares of Series E convertible preferred stock, par value $0.00001 per share (“Series E Preferred Stock”), which are convertible into common stock of the Company, $0.00001 par value per share (the “Common Stock”) and warrants to purchase 405,045 shares of Common Stock (the “Warrants” and, together with the Series E Preferred Stock, the “PIPE Securities”), for an aggregate purchase price of approximately $6.25 million and net cash proceeds of $6.2 million. Such investment is referred to as the “PIPE Financing”. The exercise price of the Series E Warrants is $0.9716, and the Series E Warrants are exercisable beginning on the issuance date and expire on the third anniversary of the issuance date.

The Series E Preferred Stock was determined to be more akin to an equity-like host than a debt-like host and was classified as permanent equity as it was not redeemable in any manner that would require classification outside of permanent equity pursuant to ASC 480-10-S99. The Series E Preferred Stock was recorded on the accompanying consolidated balance sheet at its par value. Certain embedded share-settled redemption features within the Series E Preferred Stock were bifurcated and accounted for separately a derivative liability.

The Series E Warrants and certain embedded share-settled redemption features of the Series E Preferred Stock issued were determined to be liability-classified instruments pursuant to ASC 480 and ASC 815. The embedded features of the Series E Preferred Stock were bifurcated and accounted for separately as derivative liabilities. The Company measured the warrant liabilities and bifurcated derivative liabilities at fair value on a recurring basis using Level 3 inputs as of October 1, 2025 (the issuance date), December 23, 2025 (amended warrants date) and December 31, 2025 (derivative liabilities fair value date), and June 30, 2026. See Note 8 for further information regarding the valuation methodology and assumptions used in determining the fair value of the warrant and derivative liabilities.

The Series E Preferred Stock hasno voting rights. The Series E Preferred Stock are convertible into common stock at the election of the holders of the Series E Preferred Stock at any time at an initial conversion price of $192.88 per share. The conversion price is subject to customary adjustments for stock dividends, stock splits, reclassifications, stock combinations and the like (subject to certain exceptions), anti-dilution provisions, and a floor price of $0.298.

The Series E Preferred Stock is not redeemable by the holder except in the event of 1) a liquidation, dissolution, or winding up, or 2) the Series E Preferred Stock is redeemable for common stock of the Company upon the occurrence of a change in control. Holders of the Series E Preferred Stock shall be entitled to receive dividends as authorized and declared by the Company’s Board of Directors, payable in cash, securities, or in other assets as determined by the Company’s Board of Directors.

In the event of the Company’s liquidation, dissolution, or winding up, holders of the Series E Preferred Stock will be entitled to receive out of the assets, whether capital or surplus, an amount equal to the stated value of the Series E Preferred Stock, plus any accrued and unpaid dividends thereon and any other fees or liquidated damages owed before any distribution or payment shall be made to the holders of any junior securities.

As of December 31, 2025, all 7,813 shares of Series E Preferred Stock remained outstanding. As of June 30, 2026, all 7,813 shares of Series E Preferred Stock were converted into 668,021 shares of Common Stock.

October 2024 ELOC

Concurrently, on October 2, 2024, the Company entered into a Common Stock Equity Line of Credit Purchase Agreement (the “October 2024 ELOC Purchase Agreement”) with an institutional investor (the “October 2024 ELOC Investor”), whereby the Company may sell up to $25,000,000 of the Company’s new issued Common Stock. Pursuant to the October 2024 ELOC Purchase Agreement, the October 2024 ELOC Investor shall purchase from the Company up to the lesser of (i) $25.0 million in shares of our Common Stock and (ii)390 shares, representing 19.99% of the total number of shares of Common Stock outstanding immediately prior to the execution of the October 2024 ELOC Purchase Agreement. Pursuant to the October 2024 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 Series C Redeemable Preferred Stock.

During the three months ended June 30, 2026 and 2025, the Company received proceeds of $4.3 million and $1.4 million under the ELOC, respectively. During the six months ended June 30, 2026 and 2025, the Company received proceeds of $4.3 million and $6.4 million under the ELOC, respectively.

Common Stock

As of June 30, 2026 and December 31, 2025 there were 3,793,676 and 31,201 shares of common stock issued, respectively, and 3,793,673 and 31,198 shares of common stock outstanding, respectively.

Treasury Stock

On November 10, 2022, the Board approved a stock repurchase program (the “Repurchase Program”) to allow the Company to repurchase up to 125,000 shares of common stock with a maximum price of $1.00 per share, with discretion to management to make purchases subject to market conditions. On November 18, 2022, the Board approved an increase to the maximum price to $2.00 per share. There was no expiration date for this program and prices are not adjusted for the reverse stock split to comply with the program.

There wereno repurchases of common stock during the six months ended June 30, 2026 and 2025.

On November 13, 2024, the Board terminated the Repurchase Program.

Warrants

The following summarizes the Company’s outstanding warrants, excluding contingent warrants issuable upon exercise of the outstanding warrants as of June 30, 2026:

As of June 30, 2026, the Company had outstanding warrants, which are exercisable into 24,212,655 shares of common stock. The shares of common stock underlying the outstanding warrants had an exercise price of $1.27 per share, based on the closing trading price on June 30, 2026.

On May 21, 2026, the Company effected a 1-for-10 reverse stock split of its common stock. The Series D and Series E warrants contain anti-dilution provisions that require adjustments to the exercise price and the number of shares underlying the warrants upon the occurrence of specified events. Pursuant to these provisions, following the reverse stock split, the exercise price of the affected warrants was adjusted based on the lowest volume weighted average price ("VWAP") of the Company's common stock during the 16 trading-day period following the reverse stock split, resulting in an adjusted exercise price of $0.9716 per share.

As a result of this price-reset feature, the anti-dilution adjustment increased the number of shares issuable upon exercise of the affected warrants after giving effect to the reverse stock split, rather than decreasing solely in proportion to the reverse stock split ratio. Based on the adjusted exercise price, the Company determined that an aggregate of 24,212,379 net Series D and E warrants became issuable after accounting for this adjustment.

Contingent Warrant Liabilities

As of June 30, 2026, the fair value of contingent warrant labilities includes the Series C warrants of $5,100 and those issuable upon exercise of the Inducement PIOs of approximately $20,278 totaling $25,378 included as contingent warrant liabilities in the accompanying condensed consolidated balance sheets.

As of December 31, 2025, the fair value of contingent warrant labilities includes the Series C Warrants of $6,300 and those issuable upon exercise of the Inducement PIOs of approximately $20,290 totaling $26,590 included as contingent warrant liabilities in the accompanying consolidated balance sheets.

Onconetix Equity Incentive Plans

The Company’s 2019 Equity Incentive Plan (the “2019 Plan”) was adopted by its board of directors and by its stockholders on July 1, 2019. On February 23, 2022 the Company’s board of directors adopted the Company’s 2022 Equity Incentive Plan (the “2022 Plan”), which is the successor and continuation of the Company’s 2019 Plan. Under the 2022 Plan, the Company may grant stock options, restricted stock, restricted stock units, stock appreciation rights, and other forms of awards to employees, directors, and consultants of the Company. In May 2023, the number of shares of common stock reserved for issuance under the 2022 Plan was increased to 18, and in September 2024, the number of shares of common stock reserved for issuance under the 2022 Plan was increased to 341. Stock-based awards granted during the six months ended June 30, 2025 were all granted under the 2022 Plan. There wereno stock-based awards granted during the six months ended June 30, 2026. As of June 30, 2026, there are 208 shares available for issuance under the 2022 Plan.

Stock Options

There wereno stock options granted during the three and six months ended June 30, 2026 and 2025.

The aggregate fair value of stock options that vested during the three and six months ended June 30, 2026, was approximately $0 and $0, respectively, compared to $46,000 and $92,000 for the same periods in 2025.

Restricted Stock

The following summarizes activity related to the Company’s restricted stock awards granted under the 2022 Plan for the six months ended June 30, 2026:

Proteomedix Stock Option Plan

Proteomedix sponsors a stock option plan (the “PMX Option Plan”) which provides common stock option grants to be granted to certain employees and consultants, as was determined by the board of directors of Proteomedix. In connection with the PMX Transaction, the Company assumed the PMX Option Plan.

Generally, options issued under the PMX Option Plan have a term of not more than 11 years and provide for a four-year vesting period. Stock options issued under the PMX Option Plan are measured at fair value using the Black-Scholes option pricing model.

Note 9 — Convertible Preferred Stock and Stockholders’ Equity (cont.)

There was no activity under the PMX Option Plan for the six months ended June 30, 2026 and 2025. As of June 30, 2026 and December 31, 2025, there wereno outstanding stock options.

Stock-Based Compensation

Stock-based compensation expense related to stock options and restricted stock, for the three and six months ended June 30, 2026 and 2025 was as follows:

Note 10 — Commitments and Contingencies

Office Lease

Proteomedix leases office and lab space in Zurich Switzerland. In May 2025, Proteomedix entered into a lease amendment to reduce its leased premises. Effective June 30, 2025, the Company terminated the April 2024 lease amendment, which included office space and laboratory space. Additionally, a partial termination of a prior lease amendment further reduced the office space.

This lease expired on December 31, 2025, and was renewed for a successive two-year term, resulting in an additional right-of-use asset and lease liability of approximately $49,000. The lease, as renewed, requires payments of approximately $24,000 over the next twelve months. The lease will automatically renew for successive two-year terms, unless terminated. Either party may terminate the lease with twelve months’ written notice.

Litigation

From time to time, the Company may be subject to various legal proceedings and claims that arise in the ordinary course of its business activities. As of June 30, 2026, the Company is not a party to any material legal proceedings and is not aware of any pending or threatened claims.

Indemnification

In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and provide for general indemnifications. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future but have not yet been made. To date, the Company has not been required to defend any action related to its indemnification obligations. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is not estimable at this time.

Note 11 — Related Party Transactions

On June 17, 2025, the Company entered into a separate consulting agreement with a firm affiliated with Dr. Meier. The agreement provides for the payment of certain success fees and reimbursement of related expenses. Under its terms, Dr. Meier is entitled to earn up to 10% of success fees for transactions greater than $9 million earned by the affiliated firm, payable only upon receipt of such proceeds. The Company recorded approximately $0 in related expenses during the six months ended June 30, 2026 and 2025. As of June 30, 2026 and December 31, 2025 approximately $16,500 related to this agreement was included in accounts payable.

Note 12 — Net Loss Per Share

Basic net loss per share is computed by dividing the net income or loss applicable to common shares by the weighted average number of common shares outstanding during the period. The weighted average number of shares of common stock outstanding includes pre-funded warrants because their exercise requires only nominal consideration for delivery of shares; it does not include any potentially dilutive securities or any unvested restricted shares of common stock. Certain restricted shares, although classified as issued and outstanding at June 30, 2026, are considered contingently returnable until the restrictions lapse and will not be included in the basic net loss per share calculation until the shares are vested. Unvested shares of the Company’s restricted stock do not contain non-forfeitable rights to dividends and dividend equivalents.

The two-class method is used to determine earnings per share based on participation rights of participating securities in any undistributed earnings. Each share of preferred stock that includes rights to participate in distributed earnings is considered a participating security and the Company uses the two-class method to calculate net income available to the Company’s common stockholders per common share — basic and diluted.

The following securities were excluded from the computation of diluted shares outstanding due to the losses incurred in the periods presented, as they would have had an anti-dilutive impact on the Company’s net loss:

Note 13 — Segment Information

The Company conducts its business activities and reports financial results asone business segment. The presentation of financial results asone reportable segment is consistent with the way the Company operates its business and is consistent with the manner in which the Chief Operating Decision Maker (“CODM”) evaluates performance and makes resource and operating decisions for the business. The Company’s CODM is the Chief Executive Officer. Furthermore, the Company notes that monitoring financial results as one reportable segment helps the CODM manage costs on a consolidated basis, consistent with the integrated nature of the operations. The CODM uses net loss, as reported on the Consolidated Statements of Operations and Comprehensive Loss, in evaluating performance of the Company and determining how to allocate resources of the Company as a whole. The CODM reviews consolidated financial information and does not regularly review discrete expense categories or other significant segment expenses apart from the information presented in the consolidated statement of operations and other disclosures included in the consolidated financial statements. As the CODM evaluates performance on a consolidated basis, all required financial segment information is included in the consolidated financial statements.

Note 13 — Segment Information (cont.)

Geographic Information

The distribution of revenue by geographical area was as follows:

Note 14 — Subsequent Events

Series F PIPE Financing

On July 28, 2026, the Company entered into a securities purchase agreement (the “Series F Securities Purchase Agreement”) with an accredited investor (the “Series F PIPE Investor”), pursuant to which the Company agreed to issue and sell to the Series F PIPE Investor an aggregate of 37,812 shares of Series F convertible preferred stock, par value $0.00001 per share (“Series F Preferred Stock”), for an aggregate purchase price of $30,249,600 (the “Series F PIPE Financing”), generating net cash proceeds of $249,600.

Concurrently with entering into the Series F Securities Purchase Agreement, the Company also entered into a registration rights agreement with the Series F PIPE Investor, pursuant to which it has agreed to provide the Series F PIPE Investor with certain registration rights related to the shares of Common Stock underlying the shares of Series F Preferred Stock.

July 2026 ELOC Purchase Agreement

On July 28, 2026, the Company entered into a Common Stock Purchase Agreement relating to a committed equity facility (the “July 2026 ELOC Purchase Agreement”) with an accredited investor (“July 2026 ELOC Investor”), pursuant to which, subject to the terms and conditions set forth therein, the Company has the right, but not the obligation, to direct the July 2026 ELOC Investor, from time to time and at the Company’s sole discretion, to purchase shares of the Company’s Common Stock having an aggregate purchase price of up to the lesser of (i) $750,000,000 and (ii)19.99% of the total number of shares of the Company’s Common Stock outstanding immediately prior to the execution of the July 2026 ELOC Purchase Agreement, unless stockholder approval has been obtained or an exception under the applicable Nasdaq listing rules applies. Concurrently with entering into the July 2026 ELOC Purchase Agreement, the Company entered into a Registration Rights Agreement with the July 2026 ELOC Investor (the “July 2026 ELOC Registration Rights Agreement”), pursuant to which the Company agreed to provide the July 2026 ELOC Investor with certain registration rights with respect to the securities issuable under the July 2026 ELOC Purchase Agreement.

In consideration for the July 2026 ELOC Investor’s commitment under the July 2026 ELOC Purchase Agreement, the Company agreed to pay a $30,000,000 commitment fee, which the July 2026 ELOC Investor agreed would be applied toward its purchase of Series F Preferred Stock pursuant to the Series F Securities Purchase Agreement.