MBAV: Magnetar Files 13G/A Disclosing 2.1 M Shares (7.36 %)

Rhea-AI Filing Summary

Magnetar Financial LLC and related entities filed Amendment No. 1 to Schedule 13G for M3-Brigade Acquisition V Corp. (Class A ordinary shares, CUSIP G63212107). As of 30 Jun 2025 the group beneficially owned 2,117,294 shares, or 7.36 % of the 28.75 million shares outstanding, crossing the 5 % reporting threshold.

All voting and dispositive authority is shared; the filing shows 0 shares with sole power. Ownership is spread across eight Magnetar-managed funds, the largest being Constellation Master Fund (491,903 shares) and Lake Credit Fund (363,577). Magnetar Financial acts as investment adviser; Magnetar Capital Partners is its parent; Supernova Management is the general partner, and David J. Snyderman ultimately controls the entities.

The 13G (rather than 13D) classification and the certification confirm the stake is held passively and not to influence control. No purchase prices, transaction dates, or intentions to change strategy are disclosed.

Positive

• Institutional ownership: A sophisticated asset manager holds 7.36 % of MBAV, suggesting confidence and adding specialist oversight.

Negative

• No sole voting power: Magnetar cannot act independently, limiting potential advocacy for shareholder value.

Insights

Securities Analyst

TL;DR — Institutional 7.36 % passive stake; limited governance impact.

This amendment simply updates Magnetar’s aggregate holdings, showing the firm maintains a meaningful yet passive position in MBAV. The lack of sole voting power and the 13G filing type indicate no activist agenda. While a 7 % holding signals confidence from a sophisticated investor, it neither injects capital into the SPAC nor changes its de-SPAC outlook. For valuation models this is a neutral data point—liquidity and float dynamics remain largely unchanged.

Corporate Governance Expert

TL;DR — Shared voting rights dilute any control implications.

Because Magnetar’s authority is collective across multiple funds, the group cannot unilaterally sway shareholder votes. Certification language affirms no intent to influence control, reducing governance risk for other investors. Nevertheless, should the funds coordinate with other holders, their combined 7.36 % could become relevant in tight proxy contests, so investors should monitor future 13D or activism signals.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 1)

M3-Brigade Acquisition V Corp.

(Name of Issuer)

Class A ordinary share, par value $0.0001

(Title of Class of Securities)

G63212107

(CUSIP Number)

06/30/2025

(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)

SCHEDULE 13G

CUSIP No. G63212107

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 2,117,294.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,117,294.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,117,294.00

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)

7.36 %

12

Type of Reporting Person (See Instructions)

IA, OO

SCHEDULE 13G

CUSIP No. G63212107

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 2,117,294.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,117,294.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,117,294.00

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)

7.36 %

12

Type of Reporting Person (See Instructions)

HC, PN

SCHEDULE 13G

CUSIP No. G63212107

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 2,117,294.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,117,294.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,117,294.00

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)

7.36 %

12

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13G

CUSIP No. G63212107

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 2,117,294.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,117,294.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,117,294.00

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)

7.36 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: M3-Brigade Acquisition V Corp.
(b)	Address of issuer's principal executive offices: 1700 Broadway, 19th Floor NEW YORK, NY, 10019
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 SC Fund Ltd ("SC Fund"), Purpose Alternative Credit Fund Ltd ("Purpose Credit 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"), Purpose Alternative Credit Fund - T LLC ("Purpose Credit Fund - T"), 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 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 share, par value $0.0001
(e)	CUSIP No.: G63212107
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, 2025, each of Magnetar Financial, Magnetar Capital Partners, Supernova Management and Mr. Snyderman held 2,117,294 Shares. The amount consists of (A) 491,903 Shares held for the account of Constellation Master Fund; (B) 363,577 Shares held for the account of Lake Credit Fund; (C) 342,193 Shares held for the account of Structured Credit Fund; (D) 320,799 Shares held for the account of Xing He Master Fund; (E) 213,869 Shares held for the account of Alpha Star Fund; (F) 192,477 Shares held for the account of Purpose Credit Fund; (G) 149,706 Shares held for the account of SC Fund; and (H) 42,770 Shares held for the account Purpose Credit Fund - T. The Shares held by the Magnetar Funds represent approximately 7.36% 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, 2025, each of the Reporting Persons were deemed to be the beneficial owner constituting approximately 7.36% of the total number of shares outstanding (based upon the information provided by the Issuer in its Form 10-Q filed with the SEC on May 12, 2025, there were approximately 28,750,000 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: 2,117,294
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 2,117,294
Item 5.	Ownership of 5 Percent or Less of a Class.
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:	Hayley Stein, Attorney-in-fact for David J. Snyderman, Manager of Supernova Management LLC
Date:	08/08/2025

MAGNETAR CAPITAL PARTNERS LP

Signature:	/s/ Hayley Stein
Name/Title:	Hayley Stein, Attorney-in-fact for David J. Snyderman, Manager of Supernova Management LLC
Date:	08/08/2025

SUPERNOVA MANAGEMENT LLC

Signature:	/s/ Hayley Stein
Name/Title:	Hayley Stein, Attorney-in-fact for David J. Snyderman, Manager of Supernova Management LLC
Date:	08/08/2025

DAVID J. SNYDERMAN

Signature:	/s/ Hayley Stein
Name/Title:	Hayley Stein, Attorney-in-fact for David J. Snyderman, Manager of Supernova Management LLC
Date:	08/08/2025

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 8, 2025, among the Reporting Persons. 99.2 Power of Attorney, dated as of December 22, 2022 filed by the Reporting Persons on August 8, 2025.

FAQ

How many M3-Brigade Acquisition V (MBAV) shares does Magnetar own?

As of 30 Jun 2025 Magnetar entities beneficially own 2,117,294 Class A shares.

What percentage of MBAV’s outstanding shares does this represent?

The stake equals 7.36 % of the 28.75 million shares outstanding.

Is Magnetar’s filing passive or activist?

The Schedule 13G filing and certification indicate a passive investment with no intent to influence control.

Does Magnetar have sole voting or dispositive power over MBAV shares?

No. Magnetar reports 0 shares with sole power; all voting and dispositive power is shared across its funds.

Which Magnetar fund holds the largest block of MBAV shares?

Magnetar Constellation Master Fund holds 491,903 shares, the single largest portion of the group’s stake.