Company: CCIXW
Filing Date: 2025-12-05
Form Type: S-4/A
Source: 0001193125-25-309933
Chunk: 4

Company: Churchill Capital Corp IX/Cayman
Filing Date: 2025-12-05
Form: S-4/A
Chunk 4
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 necessary, to permit further solicitation and vote of proxies in the event that there are insufficient votes for the approval of one or more of the proposals at the extraordinary general meeting (“ adjournment proposal ”); and • a prospectus for the shares of common stock of the Post-Closing Company that PlusAI securityholders will receive as consideration in the business combination. On May 14, 2025, the parties submitted a request to the SEC’s Office of Chief Accountant in the Division of Corporation Finance (the “Division”) seeking confirmation that the Staff of the Division’s Office of Chief Accountant would permit the inclusion of audited consolidated financial statements of PlusAI for the six months ended June 30, 2025 as a substitute for audited financial statements from the seven months ended July 31, 2023 that would be required to be included in this proxy statement/prospectus under SEC rules. On May 28, 2025, the Staff of the Division’s Office of Chief Accountant permitted the parties’ request. Accordingly, this proxy statement/prospectus includes audited financial statements of PlusAI for the five months ended December 31, 2023, the year ended December 31, 2024, and the six months ended June 30, 2025.

<div align='center'>1</div>

The information contained in this document is subject to completion or amendment. A registration statement relating to these securities has been filed with the United States Securities and Exchange Commission. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. This document is not an offer to sell these securities and it is not soliciting an offer to buy these securities, nor shall there be any sale of these securities, in any jurisdiction in which such offer, solicitation or sale is not permitted or would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction.

<div align='center'>PRELIMINARY — SUBJECT TO COMPLETION, DATED DECEMBER 5, 2025

PROXY STATEMENT FOR EXTRAORDINARY GENERAL MEETING IN LIEU OF AN ANNUAL MEETING OF

Churchill Capital Corp IX

PROSPECTUS FOR UP TO SHARES OF CLASS A COMMON STOCK

OF

CHURCHILL CAPITAL CORP IX

(TO BE RENAMED “PLUSAI HOLDINGS, INC.” FOLLOWING DOMESTICATION
IN THE STATE OF DELAWARE AND IN CONNECTION WITH THE
BUSINESS COMB