Hudson Bay reports 1.5M RAC shares (6.34%)

Rithm Acquisition Corp. reports a Schedule 13G/A disclosing beneficial ownership of 1,499,500 shares (Class A Ordinary Shares), representing 6.34% of the class.

Accepted by SEC EDGAR 05/11/2026 - 02:46 PM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Rithm Acquisition Corp. reports a Schedule 13G/A disclosing beneficial ownership of 1,499,500 shares (Class A Ordinary Shares), representing 6.34% of the class. The percentage is calculated using 23,660,000 Class A shares outstanding as of February 6, 2026 per the company's Form 10-Q. The shares are held in the name of HB Strategies LLC; Hudson Bay Capital Management LP acts as investment manager and Sander Gerber is identified as the reporting person with a disclaimer of beneficial ownership.

Insights

Institutional Ownership Analyst

Large passive holding disclosed: 1,499,500 shares (6.34% of Class A).

Hudson Bay Capital Management LP and Mr. Sander Gerber report ownership of 1,499,500 Class A shares held through HB Strategies LLC, representing 6.34% of the class based on February 6, 2026 outstanding shares. The filing follows Schedule 13G/A format for passive or qualifying institutional investors.

The report states that the Investment Manager may be deemed beneficial owner while Mr. Gerber disclaims beneficial ownership. Future filings may clarify voting or disposition changes if the position crosses different reporting thresholds or changes intent.

Corporate Governance Specialist

Disclosure clarifies voting and dispositive powers are shared, not sole.

The cover-page rows show Shared Voting Power and Shared Dispositive Power of 1,499,500 shares for the reporting parties. Item 4 cross-references those cover-page figures for precise voting/disposition attribution.

The filing also notes the 23,660,000 shares outstanding as of February 6, 2026 used to compute the 6.34% percentage, anchoring the ownership stake to an explicit as-of date.

Key Figures

Shares reported: 1,499,500 shares Percent of class: 6.34% Shares outstanding (as of): 23,660,000 shares

3 metrics

Shares reported 1,499,500 shares Amount beneficially owned reported on cover page

Percent of class 6.34% Calculated using 23,660,000 shares outstanding as of February 6, 2026

Shares outstanding (as of) 23,660,000 shares Outstanding Class A shares as of <date>February 6, 2026</date> per the Form 10-Q

Key Terms

Schedule 13G/A, beneficial ownership, shared dispositive power

3 terms

Schedule 13G/A regulatory

"This statement is filed by Hudson Bay Capital Management LP... (Schedule 13G/A)"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

beneficial ownership financial

"Amount beneficially owned: The information required by Item 4(a) is set forth in Row 9"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

shared dispositive power corporate

"Shared Dispositive Power 1,499,500.00"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many Rithm Acquisition Corp. (RAC) shares does Hudson Bay Capital Management report?

The filing discloses 1,499,500 Class A shares held in the name of HB Strategies LLC. This figure appears on the cover page and in Item 4 as the amount beneficially owned by the reporting parties.

What percentage of RAC does 1,499,500 shares represent?

1,499,500 shares represent 6.34% of Class A ordinary shares, calculated using 23,660,000 shares outstanding as of February 6, 2026 per the company's Form 10-Q.

Who is the reporting person on this Schedule 13G/A for RAC?

The statement is filed by Hudson Bay Capital Management LP (the Investment Manager) and Sander Gerber as reporting persons, with securities held in the name of HB Strategies LLC.

Does Mr. Sander Gerber claim beneficial ownership of the reported shares?

No. The filing states Mr. Gerber serves as managing member of the general partner but expressly disclaims beneficial ownership

What voting and dispositive powers are reported for these shares?

The cover-page rows show Shared Voting Power and Shared Dispositive Power1,499,500 shares for the reporting persons; Row 5–8 provide the detailed powers referenced in Item 4.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

Rithm Acquisition Corp.

(Name of Issuer)

Class A Ordinary Shares, $0.0001 par value

(Title of Class of Securities)

G75751100

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): G75751100

1

Names of Reporting Persons

Hudson Bay Capital Management LP

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,499,500.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,499,500.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,499,500.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.34 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP Number(s): G75751100

1

Names of Reporting Persons

Sander Gerber

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 1,499,500.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,499,500.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,499,500.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

6.34 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Rithm Acquisition Corp.
(b)	Address of issuer's principal executive offices: 799 Broadway, 8th Floor, New York, New York 10003
Item 2.
(a)	Name of person filing: This statement is filed by Hudson Bay Capital Management LP (the "Investment Manager") and Mr. Sander Gerber ("Mr. Gerber"), who are collectively referred to herein as "Reporting Persons."
(b)	Address or principal business office or, if none, residence: The address of the business office of each of the Reporting Persons is 290 Harbor Dr., Stamford, CT 06902.
(c)	Citizenship: The Investment Manager is a Delaware limited partnership. Mr. Gerber is a United States citizen.
(d)	Title of class of securities: Class A Ordinary Shares, $0.0001 par value
(e)	CUSIP No.: G75751100
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: The information required by Item 4(a) is set forth in Row 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The percentage set forth in this Schedule 13G is calculated based upon an aggregate of 23,660,000 Class A ordinary shares, par value $0.0001 (the "Class A Ordinary Shares") of Rithm Acquisition Corp. (the "Company") outstanding as of February 6, 2026, as reported in the Company's Quarterly Report on Form 10-Q for the quarterly period ended December 31, 2025 filed with the Securities and Exchange Commission on February 6, 2026. The Investment Manager serves as the investment manager to HB Strategies LLC, in whose name the securities reported herein are held. As such, the Investment Manager may be deemed to be the beneficial owner of all Class A Ordinary Shares held by HB Strategies LLC. Mr. Gerber serves as the managing member of Hudson Bay Capital GP LLC, which is the general partner of the Investment Manager. Mr. Gerber disclaims beneficial ownership of these securities.
(b)	Percent of class: 6.34%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: The information required by Item 4(c)(i) is set forth in Row 5 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(ii) Shared power to vote or to direct the vote: The information required by Item 4(c)(ii) is set forth in Row 6 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iii) Sole power to dispose or to direct the disposition of: The information required by Item 4(c)(iii) is set forth in Row 7 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
	(iv) Shared power to dispose or to direct the disposition of: The information required by Item 4(c)(iv) is set forth in Row 8 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. See Item 4(a).
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Hudson Bay Capital Management LP

Signature:	/s/ Sander Gerber
Name/Title:	Sander Gerber, Authorized Signatory
Date:	05/11/2026

Sander Gerber

Signature:	/s/ Sander Gerber
Name/Title:	Sander Gerber, Individually
Date:	05/11/2026