ACP Holdings Acquisition Corp. has a significant shareholder group led by Magnetar entities and David J. Snyderman. As of June 30, 2026, they collectively reported beneficial ownership of 1,600,000 Class A ordinary shares of ACGC, representing 7.29% of the outstanding Class A shares. These shares are held across several Magnetar-managed funds, including Constellation Master Fund, Structured Credit Fund, Alpha Star Fund, Lake Credit Fund, Xing He Master Fund, Waterfront Series A Fund, and Capital Master Fund.
The reporting persons have shared voting and dispositive power over all 1,600,000 shares, with no sole voting or dispositive power. The ownership percentage is based on 21,946,600 shares outstanding, as referenced from the issuer’s Form 10-Q. The filing is made jointly by Magnetar Financial LLC, Magnetar Capital Partners LP, Supernova Management LLC, and Mr. Snyderman.
Positive
None.
Negative
None.
Key Figures
Beneficial ownership:1,600,000 sharesOwnership percentage:7.29%Shares outstanding:21,946,600 shares+3 more
6 metrics
Beneficial ownership1,600,000 sharesClass A ordinary shares beneficially owned as of June 30, 2026
Ownership percentage7.29%Percentage of ACP Holdings Class A shares outstanding
Shares outstanding21,946,600 sharesClass A shares outstanding referenced from Form 10-Q filed May 14, 2026
Par value$0.0001Par value per Class A ordinary share of ACP Holdings Acquisition Corp.
Shared voting power1,600,000 sharesShares over which reporting persons have shared power to vote
Sole voting power0 sharesShares over which reporting persons have sole power to vote
"each of the Reporting Persons were deemed to be the beneficial owner constituting approximately 7.29%"
A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.
shared voting powerfinancial
"Shared Voting Power 1,600,000.00"
Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.
shared dispositive powerfinancial
"Shared Dispositive Power 1,600,000.00"
Schedule 13Gregulatory
"form_type": "SCHEDULE 13G"
A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.
Joint Filing Agreementregulatory
"99.1 Joint Filing Agreement, dated as of August 13, 2026"
Power of Attorneyregulatory
"99.2 Power of Attorney, dated as of December 22, 2022"
A power of attorney is a legal document that allows one person to make decisions and act on behalf of another person, often in financial or legal matters. It’s like giving someone a trusted helper or agent the authority to handle important tasks if you are unable to do so yourself. This matters to investors because it can impact how their assets are managed or transferred if they become unable to oversee their affairs.
What stake in ACGC do the Magnetar entities report owning?
Magnetar entities and David J. Snyderman report beneficial ownership of 1,600,000 Class A shares of ACGC, representing 7.29% of the outstanding Class A ordinary shares as of June 30, 2026.
How many ACP Holdings (ACGC) shares are outstanding for this 13G filing?
The reported 7.29% stake is based on 21,946,600 Class A shares outstanding, referencing information from ACP Holdings Acquisition Corp.’s Form 10-Q filed on May 14, 2026.
Who are the reporting persons in the ACGC Schedule 13G filing?
The Schedule 13G is filed on behalf of Magnetar Financial LLC, Magnetar Capital Partners LP, Supernova Management LLC, and David J. Snyderman, who together report beneficial ownership of 1,600,000 Class A shares of ACGC.
Do the Magnetar entities have sole or shared voting power over ACGC shares?
The reporting persons have shared voting power over 1,600,000 shares and no sole voting power. They also have shared dispositive power over the same shares, with no sole dispositive power reported.
How are the 1,600,000 ACGC shares allocated among Magnetar funds?
The 1,600,000 shares are spread across several Magnetar funds, including 384,000 for Constellation Master Fund, 336,000 for Structured Credit Fund, 288,000 for Alpha Star Fund, 272,000 for Lake Credit Fund, 256,000 for Xing He Master Fund, 48,000 for Waterfront Series A Fund, and 16,000 for Capital Master Fund.
What legal documents accompany the ACGC Schedule 13G filing by Magnetar?
The filing includes a Joint Filing Agreement dated August 13, 2026 and a Power of Attorney dated December 22, 2022, authorizing filings on behalf of the reporting persons.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
ACP HOLDINGS ACQUISITION CORP.
(Name of Issuer)
Class A ordinary shares, par value $0.0001
(Title of Class of Securities)
G0113G101
(CUSIP Number)
06/30/2026
(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):
G0113G101
1
Names of Reporting Persons
MAGNETAR FINANCIAL LLC
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
1,600,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,600,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,600,000.00
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)
7.29 %
12
Type of Reporting Person (See Instructions)
IA, OO
SCHEDULE 13G
CUSIP Number(s):
G0113G101
1
Names of Reporting Persons
MAGNETAR CAPITAL PARTNERS 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
1,600,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,600,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,600,000.00
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)
7.29 %
12
Type of Reporting Person (See Instructions)
HC, PN
SCHEDULE 13G
CUSIP Number(s):
G0113G101
1
Names of Reporting Persons
SUPERNOVA MANAGEMENT LLC
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
1,600,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,600,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,600,000.00
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)
7.29 %
12
Type of Reporting Person (See Instructions)
HC, OO
SCHEDULE 13G
CUSIP Number(s):
G0113G101
1
Names of Reporting Persons
DAVID J. SNYDERMAN
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
1,600,000.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,600,000.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,600,000.00
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)
7.29 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
ACP HOLDINGS ACQUISITION CORP.
(b)
Address of issuer's principal executive offices:
3131 Eastside Street, Houston, TX 77098
Item 2.
(a)
Name of person filing:
This statement is filed on behalf of each of the following person (collectively, the "Reporting Persons"):
i) Magnetar Financial LLC ("Magnetar Financial");
ii) Magnetar Capital Partners LP ("Magnetar Capital Partners");
iii) Supernova Management LLC ("Supernova Management"); and
iv) David J. Snyderman ("Mr. Snyderman").
This statement relates to the Shares (as defined herein) held for Magnetar Constellation Master Fund, Ltd ("Constellation Master Fund"), Magnetar Xing He Master Fund Ltd ("Xing He Master Fund"), Magnetar Capital Master Fund Ltd ("Capital Master Fund"), all Cayman Islands exempted companies; Magnetar Structured Credit Fund, LP ("Structured Credit Fund"), a Delaware limited partnership; Magnetar Alpha Star Fund LLC ("Alpha Star Fund"), Magnetar Lake Credit Fund LLC ("Lake Credit Fund"), Magnetar Waterfront Series A LLC ("Waterfront Series A Fund"), all Delaware limited liability companies; collectively (the "Magnetar Funds"). Magnetar Financial serves as the investment adviser to the Magnetar Funds, and as such, Magnetar Financial exercises voting and investment power over the Shares held for the Magnetar Funds' accounts. Magnetar Capital Partners serves as the sole member and parent holding company of Magnetar Financial. Supernova Management is the general partner of Magnetar Capital Partners. The administrative manager of Supernova Management is Mr. Snyderman.
(b)
Address or principal business office or, if none, residence:
The address of the principal business office of each of Magnetar Financial, Magnetar Capital Partners, Supernova Management, and Mr. Snyderman is 1603 Orrington Avenue, 13th Floor, Evanston, Illinois 60201.
(c)
Citizenship:
Place of Organization.
i) Magnetar Financial is a Delaware limited liability company;
ii) Magnetar Capital Partners is a Delaware limited partnership;
iii) Supernova Management is a Delaware limited liability company; and
iv) Mr. Snyderman is a citizen of the United States of America.
(d)
Title of class of securities:
Class A ordinary shares, par value $0.0001
(e)
CUSIP Number(s):
G0113G101
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:
As of June 30, 2026, each of Magnetar Financial, Magnetar Capital Partners, Supernova Management and Mr. Snyderman held 1,600,000 Shares. The amount consists of (A) 384,000 Shares held for the account of Constellation Master Fund; (B) 336,000 Shares held for the account of Structured Credit Fund; (C) 288,000 Shares held for the account of Alpha Star Fund; (D) 272,000 Shares held for the account of Lake Credit Fund; (E) 256,000 Shares held for the account of Xing He Master Fund; (F) 48,000 Shares held for the account of Waterfront Series A Fund; and (G) 16,000 Shares held for the account of Capital Master Fund.
The Shares held by the Magnetar Funds represent approximately 7.29% of the total number of Shares outstanding (calculated pursuant to Rule 13d-3(d)(1)(i)) of the outstanding shares of the Issuer).
(b)
Percent of class:
As of June 30, 2026, each of the Reporting Persons were deemed to be the beneficial owner constituting approximately 7.29% of the total number of shares outstanding (based upon the information provided by the Issuer in the Form 10-Q filed on 05/14/2026 there were approximately 21,946,600 Shares outstanding).
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
0
(ii) Shared power to vote or to direct the vote:
1,600,000
(iii) Sole power to dispose or to direct the disposition of:
0
(iv) Shared power to dispose or to direct the disposition of:
1,600,000
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.
Not Applicable
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.
MAGNETAR FINANCIAL LLC
Signature:
/s/ Hayley Stein
Name/Title:
Name: Hayley Stein, Title: Attorney-in-fact for David J. Snyderman, Administrative Manager of Supernova Management LLC
Date:
08/13/2026
MAGNETAR CAPITAL PARTNERS LP
Signature:
/s/ Hayley Stein
Name/Title:
Name: Hayley Stein, Title: Attorney-in-fact for David J. Snyderman, Administrative Manager of Supernova Management LLC
Date:
08/13/2026
SUPERNOVA MANAGEMENT LLC
Signature:
/s/ Hayley Stein
Name/Title:
Name: Hayley Stein, Title: Attorney-in-fact for David J. Snyderman, Administrative Manager of Supernova Management LLC
Date:
08/13/2026
DAVID J. SNYDERMAN
Signature:
/s/ Hayley Stein
Name/Title:
Name: Hayley Stein, Title: Attorney-in-fact for David J. Snyderman, Administrative Manager of Supernova Management LLC
Date:
08/13/2026
Comments accompanying signature: MAGNETAR FINANCIAL LLC By: Magnetar Capital Partners LP, its Sole Member By: Supernova Management LLC, its General Partner
MAGNETAR CAPITAL PARTNERS LP By: Supernova Management LLC, its General Partner
Exhibit Information
99.1 Joint Filing Agreement, dated as of August 13, 2026, among the Reporting Persons.
99.2 Power of Attorney, dated as of December 22, 2022 filed by the Reporting Persons on August 13, 2026.
