Onconetix files S-1 to register 100 million shares tied to Series F preferred stock

Onconetix, Inc. filed a Form S-1 with the SEC on August 11, 2026 to register the resale of up to 100,000,000 shares of common stock by selling stockholders. The shares registered are issuable only upon conversion of a portion of the 37,812 shares of Series F preferred stock issued to investors in a private placement transaction that closed on July 29, 2026, and are subject to limitations including the Nasdaq Exchange Cap and beneficial ownership limitations.¹ As a result of these conversion limitations, the company said it currently could only issue 789,426 shares of common stock upon conversion of the Series F preferred stock.¹

The Series F preferred stock is convertible into common stock at an initial conversion price of $0.9767 per share, subject to adjustment.¹ The Series F shares were issued for an aggregate purchase price of $30,249,600, paid partly in cash and partly through cancellation of commitment fees owed to the lead investor under a related equity line of credit agreement.¹

The company describes itself as commercial-stage, focused on oncology, owning Proclarix, an in vitro diagnostic test for prostate cancer approved for sale in the European Union, which it anticipates marketing in the U.S. as a lab developed test through a license agreement with LabCorp.¹ The company had also held ENTADFI, an FDA-approved combination pill for BPH, but abandoned its commercialization due to resource constraints and cash runway concerns, with no remaining inventory as of December 31, 2025.¹

Financially, Onconetix reported cash of approximately $3.7 million as of March 31, 2026, and a cash balance of approximately $5.4 million as of August 10, 2026, alongside an accumulated deficit of approximately $135.4 million.¹ The company disclosed that these factors raise substantial doubt about its ability to continue as a going concern for one year from the date of its financial statements.¹

Separately, on February 11, 2026 Onconetix entered a Share Exchange Agreement with Realbotix Corp. and related entities under which it would acquire all outstanding equity interests of Realbotix, LLC in exchange for newly issued common stock.¹ That deal may terminate if not closed by November 30, 2026, a date that can extend to December 20, 2026 under certain conditions.¹