Jade Biosciences Inc美股招股说明书(2026-03-06版)

Common StockOffered by the Selling Stockholder____________________ This prospectus supplement updates, amends and supplements the prospectus dated December 19, 2025 (the “Prospectus”), whichforms a part of our Registration Statement on Form S-1 (Registration No. 333-291541). Capitalized terms used in this prospectussupplement and not otherwise defined herein have the meanings specified in the Prospectus. This prospectus supplement is being filed to update, amend and supplement the information included in the Prospectus with theinformation contained in our Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 6, 2026,which is set forth below. This prospectus supplement is not complete without the Prospectus. This prospectus supplement should be read in conjunction withthe Prospectus, which is to be delivered with this prospectus supplement, and is qualified by reference thereto, except to the extentthat the information in this prospectus supplement updates or supersedes the information contained in the Prospectus. Please keepthis prospectus supplement with your Prospectus for future reference. Our Common Stock is traded on The Nasdaq Capital Market under the symbol “JBIO.” On March 5, 2026, the last reported saleprice for our Common Stock was $13.88 per share.____________________ An investment in our securities involves a high degree of risk. You should carefully consider theinformation under the heading “Risk Factors” beginning on page 8 of the Prospectus and anyapplicable prospectus supplement. We are a “smaller reporting company” and an “emerging growth company” under applicable federal securities laws andare subject to reduced public company reporting requirements. Neither the SEC nor any state securities commission has approved or disapproved of these securities or determined if theProspectus is truthful or complete. Any representation to the contrary is a criminal offense. Securities registered pursuant to Section 12(b) of the Act: Indicate by check mark if the Registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. YES☐NO☒ Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. YES☒NO☐ Indicate by check mark whether the Registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 duringthe preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for thepast 90 days. YES☒NO☐ Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 ofRegulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit such files). YES☒NO☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerginggrowth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2of the Exchange Act. Large accelerated filer☐Non-accelerated filer☒ Accelerated filer☐Smaller reporting company☒Emerging growth company☒ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new orrevised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☒ Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control overfinancial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its auditreport.☐ If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filingreflect the correction of an error to previously issued financial statements.☐ Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received byany of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b).☐ Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YES☐NO☒ The aggregate market value of the voting and non-voting common equity held by non-affiliates of the Registrant, based on the closing price of the shares ofcommon stock on The Nasdaq Capital Market on June 30, 2025, was approximately $289.4 million. The number of shares of Registrant’s Common Stock outstanding as of February 28, 2026 was 49,316,287. List hereunder the following do