Churchill Capital Corp IX-A美股招股说明书(2026-01-27版)

Churchill Capital Corp IX PROSPECTUS FOR UP TO 201,517,063 SHARES OF CLASS A COMMON STOCK OF CHURCHILL CAPITAL CORP IX(TO BE RENAMED “PLUSAI HOLDINGS, INC.” FOLLOWING DOMESTICATIONIN THE STATE OF DELAWARE AND IN CONNECTION WITH THEBUSINESS COMBINATION DESCRIBED IN THIS PROXY STATEMENT) This Proxy Statement/Prospectus Supplement No.1 (this “Supplement”) supplements the proxy statement/prospectus dated January12, 2026 that wasmailed by Churchill Capital Corp IX, a Cayman Islands exempted company (“CCIX”), to its shareholders on or about January12, 2026 (the “ProxyStatement/Prospectus”), in connection with the proposed business combination among CCIX, AL Merger Sub I, Inc., a Delaware corporation and direct,wholly owned Subsidiary of CCIX, AL Merger Sub II, LLC, a Delaware limited liability company and a direct, wholly owned Subsidiary of CCIX, andPlus Automation, Inc., a Delaware corporation (“PlusAI”). CCIX and PlusAI jointly filed the Proxy Statement/Prospectus with the U.S. Securities andExchange Commission (the “SEC”) as part of a registration statement on Form S-4 (Registration No.333-290370), which was declared effective onJanuary12, 2026 by the SEC. Capitalized terms used in this Supplement and not otherwise defined herein have the respective meanings ascribed tothem in the Proxy Statement/Prospectus. The purpose of this Supplement is to update and supplement the information contained in the Proxy Statement/Prospectus with information contained inthe Current Report on Form 8-K (the “Current Report”) filed by CCIX with the SEC on January27, 2026. The Current Report is attached to, and formsa part of, this Supplement. This Supplement modifies and supersedes, in part, the information in the Proxy Statement/Prospectus and is not complete without, and may not bedelivered or utilized except in combination with, the Proxy Statement/Prospectus, including any amendments or supplements thereto. Any informationin the Proxy Statement/Prospectus that is modified or superseded by the information in the Current Report shall not be deemed to constitute a part of theProxy Statement/Prospectus except as modified or superseded by this Supplement. This Supplement should be read in conjunction with the ProxyStatement/Prospectus, and if there is any inconsistency between the information in the Proxy Statement/Prospectus and this Supplement, you should relyon the information in this Supplement. YOU SHOULD CAREFULLY CONSIDER THE MATTERS DISCUSSED UNDER “RISK FACTORS” IN THEPROXY STATEMENT/PROSPECTUS. NEITHER THE SEC NOR ANY STATE SECURITIES REGULATORY AGENCY HAS APPROVED OR DISAPPROVED THE TRANSACTIONSDESCRIBED IN THE PROXY STATEMENT/PROSPECTUS OR THIS SUPPLEMENT, PASSED UPON THE MERITS OR FAIRNESS OF THEBUSINESS COMBINATION OR RELATED TRANSACTIONS OR PASSED UPON THE ADEQUACY OR ACCURACY OF THE DISCLOSUREIN THE PROXY STATEMENT/PROSPECTUS OR THIS SUPPLEMENT. ANY REPRESENTATION TO THE CONTRARY CONSTITUTES ACRIMINAL OFFENSE. The date of this Supplement is January27, 2026. CURRENT REPORTPURSUANT TO SECTION 13 OR 15(d)OF THE SECURITIES EXCHANGE ACT OF 1934 Date of Report (Date of earliest event reported): January 27, 2026 CHURCHILL CAPITAL CORP IX (Exact name of registrant as specified in its charter) 86-1885237(IRS EmployerIdentification No.) 001-42041(CommissionFile Number) 640 Fifth Avenue, 14th FloorNew York, NY 10019(Address of principal executive offices, including zip code) Registrant’s telephone number, including area code: (212) 380-7500 Not Applicable(Former name or former address, if changed since last report) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of thefollowing provisions: ☒Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)☒Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section12(b) of the Act: Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of thischapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with anynew or revised financial accounting standards provided pursuant to Section13(a) of the Exchange Act.☐ Item 7.01Regulation FD Disclosure. On January27, 2026, Churchill Capital Corp IX, a Cayman Islands exempted company (“Churchill”), and Plus Automation, Inc, a Delawarecorporation (“PlusAI”), issued a joint press release announcing the postponement of Churchill’s extraordinary general meeting of shareholders to vo