Soligenix美国招股说明书（2026年5月28日版）

Up to $2,956,000 COMMON STOCK Thisprospectus supplement(the“Prospectus Supplement”)amends and supplements theinformation in the prospectus supplement dated January 23, 2026 (the “January Prospectus”), filed as apart of our registration statement on Form S-3 (File No. 333-274265) (the “Registration Statement”) andthe prospectus dated December 15, 2023 contained therein (the “December Prospectus” and, together withthe January Prospectus, the “Prior Prospectus”), relating to the offering, issuance and sale by us of ourcommon stock, par value $0.001 per share, from time to time, that may be issued and sold under the AtMarket Issuance Sales Agreement (the “Sales Agreement”), dated January 23, 2026, by and between usand Rodman & Renshaw LLC, as sales agent. This Prospectus Supplement should be read in conjunction We are filing this Prospectus Supplement to amend the Prior Prospectus to update the maximumdollar amount of shares we are eligible to sell under the Sales Agreement and the Prospectus Supplement.As of the date hereof, the current aggregate market value of our outstanding common stock held by non-affiliates, or public float, is $24,511,625, which was calculated based on 17,261,708 outstanding shares ofcommon stock held by non-affiliates as of such date and a price of $1.42 per share, the last reported sales Pursuant to General Instruction I.B.6, as of the date hereof, we currently may offer and sellcommon stock having an aggregate offering price of up to $2,956,000 under the Sales Agreement, whichamount is in addition to the common stock that we have sold to date in accordance with the SalesAgreement under the Prior Prospectus. If our public float increases such that we may sell additionalamounts under the Sales Agreement and the Registration Statement of which this Prospectus Supplementand the Prior Prospectus are a part, we will file another prospectus supplement prior to making additionalsales. Pursuant to General Instruction I.B.6 of Form S-3, in no event will we sell securities in a public Our common stock is listed on the Nasdaq Capital Market under the symbol “SNGX.” On May27, 2026, the last reported sale price of our common stock on the Nasdaq Capital Market was $0.87 per We are a smaller reporting company as defined under Rule 405 of the Securities Act of 1933, asamended, and as such, we have elected to comply with certain reduced public company reporting “Summary — Implications of Being a Smaller Reporting Company” on page S-3 of the Prior Prospectus Investing in our common stock involves a high degree of risk. Before buying any shares, youshould read the discussion of material risks of investing in our common stock in “Risk Factors”beginning on page S-7 of the Prior Prospectus, and in our most recent Annual Report on Form 10-Kand in the risks discussed under similar headings in the documents incorporated by reference in this Neither the Securities and Exchange Commission nor any state securities commission hasapproved or disapproved of these securities or passed upon the adequacy or accuracy of the Prior Rodman & Renshaw LLC The date of this Prospectus Supplement is May 28, 2026.