SeaStar Medical Holding Corp美股招股说明书(2026-05-13版)

Common Stock This prospectus relates to the resale, from time to time, of up to 2,000,000 shares of our Common Stock by Lincoln Park CapitalFund, LLC (“Lincoln Park” or the “selling stockholder”). The shares of Common Stock being offered by the selling stockholder have been or may be purchased pursuant to the purchaseagreement, dated April 25, 2025, that we entered into with Lincoln Park (the “Purchase Agreement”). See “The Lincoln ParkTransaction” for a description of the Purchase Agreement and “Selling Stockholder” for additional information regarding LincolnPark. The prices at which Lincoln Park may sell the shares will be determined by the prevailing market price for the shares or innegotiated transactions. We are not selling any securities under this prospectus and will not receive any of the proceeds from the saleof shares of Common Stock by the selling stockholder. We may receive up to $14,657,887.43 (in addition to the $342,112.57previously received from sales made pursuant to the Purchase Agreement prior to the date of this prospectus) aggregate gross proceeds(subject to certain limitations) under the Purchase Agreement from any sales we make to Lincoln Park pursuant to the PurchaseAgreement after the date of this prospectus. As of April 20, 2026, we have sold an aggregate of 138,184 shares of our common stockto Lincoln Park for gross proceeds of approximately $342,112.57 under the Purchase Agreement, which shares (together with the23,641 Commitment Shares) were registered for resale by Lincoln Park under the May 2025 Registration Statement and 335,457shares of Common Stock remain to be sold pursuant to the May 2025 Registration Statement. The selling stockholder may sell or otherwise dispose of the shares of Common Stock described in this prospectus in a number ofdifferent ways and at varying prices. See “Plan of Distribution” for more information about how the selling stockholder may sell orotherwise dispose of the shares of Common Stock being registered pursuant to this prospectus. The selling stockholder is an“underwriter” within the meaning of Section 2(a)(11) of the Securities Act. The selling stockholder will pay all brokerage fees and commissions and similar expenses. We will pay the expenses (exceptbrokerage fees and commissions and similar expenses) incurred in registering the shares, including legal and accounting fees. See“Plan of Distribution.” We are a “smaller reporting company” under the federal securities laws and, as such, are subject to reduced public companyreporting requirements. See “Implications of Being a Smaller Reporting Company.” We are an “emerging growth company” under the federal securities laws and, as such, are subject to reduced public companyreporting requirements. See “Implications of Being an Emerging Growth Company.” Our Common Stock and warrants exercisable for one share of Common Stock for $11.50 per share (the “Listed Warrants”) aretraded on the Nasdaq Stock Market under the symbols “ICU” and “ICUCW,” respectively. On April 20, 2026, the closing price of ourCommon Stock was $4.63 per share, and the closing price of our Listed Warrants, was $0.0249 per warrant. On January 5, 2026, we effected a 1-for-10 reverse stock split (the “Reverse Split”) of our issued and outstanding shares ofCommon Stock, and our shares of Common Stock began trading on a split-adjusted basis on the Nasdaq Capital Market on January 5,2026 under the same symbol “ICU”. All of our stock options and warrants outstanding immediately prior to the Reverse Split wereproportionally adjusted except for the Listed Warrants and the private placement warrants that were issued as part of the SPACtransaction, which total 16,788,000 outstanding warrants in the aggregate (the “Unadjusted Warrants”). The Unadjusted Warrantsretain an $11.50 exercise price each and require the exercise of 250 warrants to purchase one share of Common Stock. Unlessotherwise indicated, all other share and per share prices in this prospectus have been adjusted to reflect the Reverse Split. Investing in our securities involves a high degree of risk. You should read “Risk Factors” beginning on page 6 of thisprospectus, and under similar headings in the documents incorporated by reference in this prospectus, as well as in anyamendments or supplements to this prospectus, to read about factors to consider before purchasing our securities. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminaloffense. The date of this prospectus is May 11, 2026. TABLE OF CONTENTS ABOUT THIS PROSPECTUSiiCAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSiiiSUMMARY1THE OFFERING5RISK FACTORS6OUR AGREEMENTS WITH LINCOLN PARK10USE OF PROCEEDS14SELLING STOCKHOLDER15DILUTION16PLAN OF DISTRIBUTION17MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS36DESCRIPTION OF SEC