Onconetix, Inc. filed a Form 8-K on November 9, 2026, disclosing that its previously approved one-for-ten reverse stock split of its common stock became effective at 12:01 a.m. Eastern Time on November 6, 2026.

Key Highlights

  • Reverse split ratio: Every ten shares of issued and outstanding common stock were automatically combined into one share.
  • Effective time: The amendment became effective at 12:01 a.m. Eastern Time on November 6, 2026.
  • Share count reduced: Outstanding shares declined from approximately 6.7 million to approximately 670,000, according to the filing.
  • No authorized share reduction: The number of authorized shares of common stock and the par value per share were not changed.
  • Fractional shares: No fractional shares were issued; eligible stockholders will instead receive a cash payment equal to the fraction multiplied by the closing sale price on the trading day immediately preceding the effective time, as adjusted.
  • New CUSIP: The common stock began trading on a split-adjusted basis on November 6, 2026, under symbol ONCO with new CUSIP number 68237Q500.

Onconetix Reverse Stock Split: Amendment Filed and Effect on Outstanding Shares

According to the filing, the Board of Directors of Onconetix, Inc. approved the one-for-ten reverse stock split on October 22, 2026, acting under authority granted by stockholders at a special meeting held on April 30, 2026. That board approval was previously disclosed in a Current Report on Form 8-K filed on October 26, 2026. On November 4, 2026, the company filed a Certificate of Amendment to its Amended and Restated Certificate of Incorporation, as amended, with the Secretary of State of the State of Delaware to effect the split.

The filing states that at the effective time, every ten shares of issued and outstanding common stock, par value $0.00001 per share, were automatically combined into one share. The company disclosed that no corresponding reduction was made to the number of authorized shares of common stock and that there was no change in par value per share. As a result, the filing reports, outstanding shares were reduced from approximately 6.7 million to approximately 670,000.

The filing also states that proportional adjustments were made to shares issuable upon exercise or conversion of outstanding equity awards, convertible preferred stock, and warrants, along with applicable exercise or conversion prices. Stockholders who would otherwise have received fractional shares are instead entitled to a cash payment, without interest, based on the closing sale price on The Nasdaq Capital Market on the trading day immediately preceding the effective time, as adjusted to reflect the reverse stock split. The company's common stock, listed on NASDAQ:ONCO, began trading on a split-adjusted basis on November 6, 2026, under the new CUSIP number 68237Q500. The filing was signed by David A. White, Chief Executive Officer.

What Was Disclosed

Onconetix disclosed the completion of a 1-for-10 reverse stock split, effective November 6, 2026, which reduced outstanding common shares from approximately 6.7 million to approximately 670,000, with no change to authorized shares or par value.