Sermonix Pharmaceuticals, Inc. and its CEO David J. Portman filed Amendment No. 1 to a Schedule 13D with the SEC on October 28, 2026, disclosing the partial exercise of a prefunded warrant and a distribution-in-kind of LeonaBio, Inc. common stock effective October 26, 2026.

Key Highlights

  • Warrant exercised: Sermonix exercised a prefunded warrant for 3,149,470 shares of LeonaBio common stock on October 26, 2026.
  • Beneficial ownership: Sermonix and David Portman each report shared beneficial ownership of 3,149,470 shares, representing 25.1% of LeonaBio's common stock.
  • Warrant assigned: The remaining prefunded warrant to acquire 2,352,932 shares was assigned to Perceptive Xontogeny Venture Fund 11, LP ("PXV II") as a distribution-in-kind.
  • Distribution declared: Sermonix declared a distribution-in-kind of 4,725,754 shares of LeonaBio common stock (including the 2,352,932 assigned to PXV II), payable on October 26, 2026.
  • Creditor assignment: Sermonix entered into an agreement to assign 170,940 shares to a creditor in satisfaction of amounts owed, with the transfer to occur on or shortly after October 26, 2026.
  • Consulting options: David Portman was granted options to purchase 350,000 shares of LeonaBio common stock in April 2026 for consulting services, subject to a vesting schedule commencing April 2027.
  • Shares outstanding basis: The 25.1% ownership percentage is based on 9,421,663 shares of LeonaBio common stock outstanding, as disclosed in LeonaBio's quarterly report filed August 14, 2026.

Sermonix Completes Partial Warrant Exercise and Distribution Plan for LeonaBio Shares

According to the filing, Sermonix Pharmaceuticals, Inc., a Delaware corporation whose principal business is described as "pharmaceutical intellectual property licensing and clinical development," holds a prefunded warrant that was originally issued in connection with a License Agreement and Securities Purchase Agreement entered into with LeonaBio, Inc. on December 18, 2025. Under the License Agreement, Sermonix granted LeonaBio an exclusive worldwide license (excluding certain Asian territories) to develop, manufacture, and commercialize lasofoxifene, in exchange for royalties, milestone payments, and the prefunded warrant. Those transactions closed on December 23, 2025, according to the filing.

The filing discloses that Sermonix became eligible on August 24, 2026, to exercise its prefunded warrants covering a total of 5,502,402 shares of LeonaBio common stock. The warrant had previously been subject to an exercise cap equal to 4.99% of outstanding LeonaBio common stock, applicable to Sermonix and any affiliates on an aggregate basis, according to the filing. Sermonix subsequently exercised the warrant for 3,149,470 shares effective October 26, 2026, and assigned the remaining right to acquire 2,352,932 shares to PXV II as a distribution-in-kind, with a new prefunded warrant issued to PXV II for those remaining shares, the filing states.

The filing further notes that the remaining distribution of LeonaBio common stock to Sermonix equity owners other than PXV II "is contemplated to occur pursuant to the previously disclosed plan of distribution, but has not yet occurred." The filing also identifies PXV II and HPW Asset Management Limited as shareholders of Sermonix with the right to receive or direct the receipt of dividends from, or proceeds from the sale of, more than 5% of LeonaBio common stock. David Portman, identified in the filing as CEO of Sermonix, reports shared voting and shared dispositive power over the same 3,149,470 shares, with no sole voting or dispositive power.

What Was Disclosed

Sermonix Pharmaceuticals and its CEO David Portman disclosed the partial exercise of a prefunded warrant for 3,149,470 LeonaBio shares, a distribution-in-kind of the remaining warrant to PXV II, and aggregate beneficial ownership of 25.1% of LeonaBio common stock as of October 26, 2026.