Sec Form 3 Filing - Nierenberg Michael @ Rithm Acquisition Corp. - 2025-02-26

FORM 3 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Nierenberg Michael 2. Issuer Name and Ticker or Trading Symbol Rithm Acquisition Corp. [ RAC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) CHIEF EXECUTIVE OFFICER (Last) (First) (Middle) 799 BROADWAY 3. Date of Earliest Transaction (MM/DD/YY) 02/26/2025 (Street) NEW YORK, NY10003 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Class B ordinary shares ( 3 ) ( 3 ) ( 3 ) Class A ordinary shares 5,675,000 ( 4 ) I See footnotes ( 1 ) ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Nierenberg Michael 799 BROADWAY NEW YORK, NY10003 X CHIEF EXECUTIVE OFFICER Signatures /s/ MICHAEL NIERENBERG 02/26/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Class B Ordinary shares are owned directly by Rithm Acquisition Corp Sponsor LLC (the "Sponsor"). The Sponsor is controlled by Rithm Capital Corp. ("Rithm") and Mr. Michael Nierenberg (the "reporting person"), as a result of his role as chief executive officer, chairman of the board and president of Rithm. As a result, each of the Sponsor, Rithm and the reporting person may be deemed to have beneficial ownership of the Class B ordinary shares and the Private Placement Units (as defined below) (including the Private Placement Shares (as defined below) included in such units) held by our Sponsor. The reporting person will own approximately 25% of the Class B LLC interests in the Sponsor ((which represent the economic rights attributable to the founder share, as described in the issuer's registration statement on Form S-1 (File No. 333-284671) (the "Registration Statement")). ( 2 )The reporting person under this Form 3 disclaims beneficial ownership of the Class B ordinary shares reported herein except to the extent of its respective pecuniary interest therein and the filing of this Form 3 shall not be construed as an admission that the reporting person is the beneficial owner of any Class B ordinary share covered by this Form 3. ( 3 )Pursuant to the Issuer's amended and restated memorandum and articles of association, the Class B ordinary shares have no expiration date and will automatically convert into Class A ordinary shares at the time of the Issuer's initial business combination on a one-for-one basis subject to adjustment pursuant to certain anti-dilution rights. ( 4 )The Class B ordinary shares reported herein include up to 750,000 Class B ordinary shares that are subject to forfeiture to the extent the underwriters of the initial public offering of the issuer's securities do not exercise in full their over-allotment option, as described in the Registration Statement. The over-allotment option of the underwriters expires 45-day from the date of the final prospectus related to the issuer's initial public offering.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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