Form 8-K

8-K — Onconetix, Inc.

Accession: 0001213900-26-112527

Filed: 2026-10-26

Period: 2026-10-22

CIK: 0001782107

SIC: 2834 (PHARMACEUTICAL PREPARATIONS)

Item: Other Events

Item: Financial Statements and Exhibits

Documents

8-K — ea0309723-8k_onconetix.htm (Primary)

EX-99.1 — PRESS RELEASE, DATED OCTOBER 26, 2026 (ea030972301ex99-1.htm)

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8-K — CURRENT REPORT

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported):

October 22, 2026

Onconetix, Inc.

(Exact name of registrant as specified in its charter)

Delaware

001-41294

83-2262816

(State or other jurisdiction

of incorporation)

(Commission File Number)

(IRS Employer

Identification No.)

201 E. Fifth Street, Suite 1900

Cincinnati, Ohio

45202

(Address of principal executive offices)

(Zip Code)

Registrant’s telephone number, including

area code: (513) 620-4101

Not Applicable

(Former name or former address, if changed since

last report)

Check the appropriate box below if the Form 8-K

filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b)

of the Act:

Title of each class

Trading Symbol(s)

Name of each exchange on which registered

Common Stock, par value $0.00001 per share

ONCO

The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant

is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the

Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☒

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 13(a) of the Exchange Act. ☐

Item 8.01 Other Events.

previously reported on a Current Report on Form 8-K filed on May 4, 2026, Onconetix, Inc. (the “Company”) held a special meeting

of stockholders (the “Special Meeting”) on April 30, 2026. At the Special Meeting, the Company’s stockholders approved

the proposal to grant discretionary authority to the Company’s Board of Directors (the “Board”) to amend the Company’s

Amended and Restated Certificate of Incorporation, as amended (the “Charter”), to effect one or more reverse stock splits

of the Company’s issued and outstanding common stock, par value $0.00001 per share (the “Common Stock”), at ratios ranging

from one-for-two (1:2) to one-for-ten (1:10), at any time prior to the one-year anniversary of the Special Meeting, with the ratio for

each reverse stock split to be determined by the Board, provided that the reverse stock splits effected pursuant to such authorization

shall not, in the aggregate, exceed one-for-one hundred (1:100) (the “Reverse Stock Split Proposal”).

Pursuant

to the foregoing authorization, the Company previously effected a one-for-ten (1:10) reverse stock split of its Common Stock, effective

May 21, 2026.

October 22, 2026, the Board determined to effect an additional reverse stock split of the Common Stock at a ratio of one-for-ten (1:10)

(the “Reverse Stock Split”). Together with the reverse stock split effected on May 21, 2026, the Reverse Stock Split will

result in an aggregate reverse stock split ratio of one-for-one hundred (1:100) pursuant to the Reverse Stock Split Proposal.

connection with the Reverse Stock Split, the Company expects to file a Certificate of Amendment to the Charter with the Secretary of State

of the State of Delaware (the “Amendment”) on November 5, 2026. The Reverse Stock Split is expected to become effective in

accordance with the terms of the Amendment at 12:01 a.m. Eastern Time on November 6, 2026 (the “Effective Time”). The Common

Stock is expected to begin trading on a split-adjusted basis when The Nasdaq Stock Market opens on November 6, 2026, under the existing

trading symbol “ONCO” and a new CUSIP number, 68237Q500.

the Effective Time, every ten (10) shares of the Company’s issued and outstanding Common Stock will automatically be combined into

one (1) issued and outstanding share of Common Stock, without any corresponding reduction in the number of authorized shares of Common

Stock or any change in the par value per share. Stockholders holding shares through a brokerage account will have their shares automatically

adjusted to reflect the Reverse Stock Split. Stockholders holding shares of Common Stock in certificated form will not be required to

exchange their existing stock certificates for new stock certificates in connection with the Reverse Stock Split, although they may do

so if they wish.

The

Reverse Stock Split will affect all stockholders uniformly and will not alter any stockholder’s percentage ownership interest in

the Company, except to the extent that the Reverse Stock Split would result in a stockholder owning a fractional share. No fractional

shares will be issued in connection with the Reverse Stock Split. Stockholders who would otherwise be entitled to receive a fractional

share will instead receive a cash payment (without interest) equal to such fraction multiplied by the closing sale price per share of

the Common Stock on The Nasdaq Capital Market at the close of business on the trading day immediately preceding the Effective Time, as

adjusted to give effect to the Reverse Stock Split. The Reverse Stock Split is expected to reduce the number of outstanding shares of

Common Stock from approximately 5.9 million shares to approximately 589,000 shares.

Proportional

adjustments will be made to the number of shares of Common Stock issuable upon exercise or conversion of the Company’s outstanding

equity awards, convertible preferred stock and warrants, as applicable, as well as the applicable exercise or conversion prices, in accordance

with the terms of such securities. Stockholders with shares in brokerage accounts should direct any questions concerning the Reverse Stock

Split to their broker; all other stockholders may direct questions to the Company’s transfer agent, Continental Stock Transfer &

Trust Company, at (212) 509-4000.

October 26, 2026, the Company issued a press release announcing the Reverse Stock Split, a copy of which is filed as Exhibit 99.1 to this

Current Report on Form 8-K and incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

The following exhibits are being filed or furnished,

as applicable, with this Current Report on Form 8-K:

Exhibit No.

Description

99.1

Press Release, dated October 26, 2026.

104

Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities

Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Onconetix, Inc.

October 26, 2026

By:

/s/ David A. White

Name:

David A. White

Title:

Chief Executive Officer

EX-99.1 — PRESS RELEASE, DATED OCTOBER 26, 2026

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Exhibit 99.1

Onconetix Announces Reverse Stock Split

CINCINNATI, Ohio, Oct. 26, 2026 (GLOBE NEWSWIRE) -- Onconetix, Inc. (Nasdaq: ONCO) (the “Company”), today announced that its Board of Directors has approved

a one-for-ten (1-for-10) reverse stock split of the Company’s outstanding common stock. The reverse split is expected to become

effective at 12:01 a.m. Eastern Time on November 6, 2026. The Company’s common stock has been assigned a new CUSIP number, 68237Q500,

in connection with the reverse stock split.

Following the reverse split, every ten (10) shares

of Onconetix common stock will be automatically exchanged into one share of common stock. The Company’s common stock will continue

to trade on Nasdaq under the symbol “ONCO”.

The reverse split will reduce the number of outstanding

shares of common stock from approximately 5,886,774 shares outstanding as of October 21, 2026 to approximately 588,677 shares, before

giving effect to adjustments resulting from the treatment of fractional shares. The reverse stock split will not change the number of

authorized shares of common stock, which will remain at 250,000,000 shares, or the par value of the Company’s common stock, which

will remain at $0.00001 per share. No fractional shares will be issued in connection with the reverse split. Stockholders who would otherwise

be entitled to receive fractional shares will instead receive cash payments in lieu of such fractional shares.

The reverse stock split will be effected simultaneously

for all outstanding shares of the Company’s common stock and will affect all of the Company’s stockholders uniformly. The

reverse stock split will not affect any stockholder’s percentage ownership interest in the Company, except to the extent that a

stockholder would otherwise be entitled to receive a fractional share for which cash will be paid in lieu thereof. The reverse stock split

will not affect the par value of the Company’s common stock and will also not affect the number of authorized shares or par value

of our preferred stock. The rights and privileges of the holders of the common stock will be unaffected by the reverse stock split. Proportionate

adjustments will be made, as applicable and in accordance with their respective terms, to the exercise or conversion prices and the number

of shares issuable under the Company’s outstanding options, warrants, convertible securities and equity incentive plans.

About Onconetix, Inc.

Onconetix, Inc. (Nasdaq: ONCO) is a commercial-stage

biotechnology company focused on the research, development, and commercialization of innovative oncology solutions. Onconetix owns Proclarix®,

an in vitro diagnostic test for prostate cancer originally developed by Proteomedix and approved for sale in the European Union under

the IVDR, which it anticipates will be marketed in the U.S. as a lab developed test through its license agreement with Labcorp. For more

information, visit www.onconetix.com.

Forward-Looking Statements

Certain statements in this press release are forward-looking

within the meaning of the Private Securities Litigation Reform Act of 1995. These statements may be identified by the use of forward-looking

words such as “anticipate,” “believe,” “forecast,” “estimate,” “expect,” and

“intend,” among others. These forward-looking statements are based on Onconetix’s current expectations and actual results

could differ materially. Investors should read the risk factors set forth in Onconetix’s Annual Report on Form 10-K filed with the

SEC on March 13, 2026, and periodic reports filed with the SEC on or after the date thereof. All forward-looking statements are expressly

qualified by all such risk factors and other cautionary statements. The information set forth herein speaks only as of the date hereof.

Onconetix does not undertake an obligation to update or revise any forward-looking statement except as required by applicable law.

Investor and Media Contact:

Onconetix, Inc.

201 E. Fifth Street, Suite 1900

Cincinnati, OH 45202

Phone: (513) 620-4101

Email: investors@onconetix.com

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