Company: CCIXW
Filing Date: 2025-12-05
Form Type: S-4/A
Source: 0001193125-25-309933
Chunk: 23

Company: Churchill Capital Corp IX/Cayman
Filing Date: 2025-12-05
Form: S-4/A
Chunk 23
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 to the matters that this proxy statement/prospectus describes other than those contained in this proxy statement/prospectus, and, if given or made, the information or representation must not be relied upon as having been authorized by CCIX or PlusAI. This proxy statement/prospectus does not constitute an offer to sell or a solicitation of an offer to buy securities or a solicitation of a proxy in any jurisdiction where, or to any person to whom, it is unlawful to make such an offer or a solicitation. Neither the delivery of this proxy statement/prospectus nor any distribution of securities made under this proxy statement/prospectus will, under any circumstances, create an implication that there has been no change in the affairs of CCIX or PlusAI since the date of this proxy statement/prospectus or that any information contained herein is correct as of any time subsequent to such date.

The accompanying proxy statement/prospectus incorporates important information that is not included in or delivered with this proxy statement/prospectus. This information is available for you to review through the SEC’s website atwww.sec.gov .

You may request copies of this proxy statement/prospectus or other information concerning CCIX, without charge, by written request directed to:

<div align='center'>Churchill Capital Corp IX

640 Fifth Avenue, 14th Floor

New York, NY 10019
Attention: Jay Taragin, Chief Financial Officer

Email:info@churchillcapitalcorp.com

or:

Morrow Sodali LLC

333 Ludlow Street, 5th Floor, South Tower

Stamford, CT 06902Call Toll-Free (800) 662-5200 or (203) 658-9400
Email:ALCC.info@investor.morrowsodali.com</div>

In order for you to receive timely delivery of the documents in advance of the extraordinary general meeting of CCIX to be held on , 2025, you must request the information no later than five business days prior to the date of the extraordinary general meeting.

<div align='center'>CHURCHILL CAPITAL CORP IX
640 Fifth Avenue, 14th Floor
New York, NY 10019

14

NOTICE OF EXTRAORDINARY GENERAL MEETING OF SHAREHOLDERS
TO BE HELD ON , 2025

TO THE SHAREHOLDERS OF CHURCHILL CAPITAL CORP IX</div>

NOTICE IS HEREBY GIVEN that an extraordinary general meeting (the “extraordinary general meeting