Magnetar group discloses 5.22% JAB Acquisition Corp I (JAB) stake in 13G filing

Rhea-AI Filing Summary

JAB Acquisition Corp I received a Schedule 13G from Magnetar-related entities reporting a significant passive ownership stake in its Class A ordinary shares. As of June 30, 2026, Magnetar Financial LLC, Magnetar Capital Partners LP, Supernova Management LLC, and David J. Snyderman together reported beneficial ownership of 900,000 Class A shares.

These shares are held across several Magnetar-managed funds and represent 5.22% of JAB Acquisition Corp I’s 17,250,000 Class A shares outstanding, based on issuer information in a June 12, 2026 Form 8-K. The reporting persons have shared voting and dispositive power over all 900,000 shares and no sole voting or dispositive power.

Key Figures

Shares beneficially owned: 900,000 shares Ownership percentage: 5.22% Shares outstanding: 17,250,000 shares +4 more

7 metrics

Shares beneficially owned 900,000 shares Class A ordinary shares beneficially owned as of June 30, 2026

Ownership percentage 5.22% Percentage of JAB Acquisition Corp I Class A shares outstanding

Shares outstanding 17,250,000 shares Class A shares outstanding based on June 12, 2026 Form 8-K

Constellation Master Fund holding 216,000 shares Portion of JAB shares held for Magnetar Constellation Master Fund, Ltd

Structured Credit Fund holding 189,000 shares Portion of JAB shares held for Magnetar Structured Credit Fund, LP

Alpha Star Fund holding 153,000 shares Portion of JAB shares held for Magnetar Alpha Star Fund LLC

Xing He Master Fund holding 153,000 shares Portion of JAB shares held for Magnetar Xing He Master Fund Ltd

Key Terms

Schedule 13G, beneficial owner, shared voting power, shared dispositive power, +2 more

6 terms

Schedule 13G regulatory

"This statement is filed on behalf of each of the following person"

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.

beneficial owner financial

"each of the Reporting Persons were deemed to be the beneficial owner"

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 power financial

"Shared Voting Power 900,000.00"

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 power financial

"Shared Dispositive Power 900,000.00"

Rule 13d-3(d)(1)(i) regulatory

"calculated pursuant to Rule 13d-3(d)(1)(i)"

investment adviser financial

"Magnetar Financial serves as the investment adviser to the Magnetar Funds"

An investment adviser is a person or firm that professionally manages money and gives recommendations about buying, selling, or holding investments. Like a financial coach or guide, they have a legal duty to act in a client's best financial interest, so their advice, fees and potential conflicts can directly affect returns and risk — making their role important for investors who want informed, accountable help with portfolios.

FAQ

What ownership stake in JAB (JAB) is reported in this Schedule 13G?

The reporting Magnetar entities disclose beneficial ownership of 900,000 Class A shares of JAB Acquisition Corp I, representing approximately 5.22% of the issuer’s outstanding Class A ordinary shares as of June 30, 2026.

Who are the reporting persons in the JAB (JAB) Schedule 13G filing?

The filing is made on behalf of Magnetar Financial LLC, Magnetar Capital Partners LP, Supernova Management LLC, and David J. Snyderman, who collectively report beneficial ownership and shared voting and investment power over the 900,000 JAB Class A shares.

How many JAB (JAB) shares are outstanding according to the Schedule 13G?

The Schedule 13G states that, based on issuer information in a June 12, 2026 Form 8-K, there were approximately 17,250,000 JAB Acquisition Corp I Class A ordinary shares outstanding used to calculate the 5.22% ownership stake.

How is the 900,000-share JAB (JAB) position allocated among Magnetar funds?

The 900,000 JAB shares are held across multiple Magnetar funds, including 216,000 for Constellation Master Fund, 189,000 for Structured Credit Fund, and several others, with individual fund positions ranging from 9,000 to 216,000 shares.

What voting and dispositive powers do the Magnetar entities have over JAB (JAB) shares?

The reporting persons indicate 0 shares with sole voting or dispositive power and 900,000 shares with shared voting and shared dispositive power, reflecting their investment adviser and control structure over the Magnetar funds.

What legal structures are involved in the Magnetar stake in JAB (JAB)?

The stake is held via several Cayman and Delaware entities. Magnetar Financial acts as investment adviser, Magnetar Capital Partners is its sole member, Supernova Management is general partner of Magnetar Capital Partners, and David J. Snyderman is administrative manager of Supernova Management.

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Available on EDGAR 08/13/2026 - 06:17 AM Accepted by SEC EDGAR 08/13/2026 - 06:16 AM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

JAB ACQUISITION CORP I

(Name of Issuer)

Class A ordinary shares, par value $0.0001

(Title of Class of Securities)

G50004103

(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): G50004103

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 900,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 900,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

900,000.00

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)

5.22 %

12

Type of Reporting Person (See Instructions)

IA, OO

SCHEDULE 13G

CUSIP Number(s): G50004103

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 900,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 900,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

900,000.00

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)

5.22 %

12

Type of Reporting Person (See Instructions)

HC, PN

SCHEDULE 13G

CUSIP Number(s): G50004103

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 900,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 900,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

900,000.00

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)

5.22 %

12

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13G

CUSIP Number(s): G50004103

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 900,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 900,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

900,000.00

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)

5.22 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: JAB ACQUISITION CORP I
(b)	Address of issuer's principal executive offices: 270 SYLVAN AVENUE SUITE 2230, ENGLEWOOD CLIFFS, NJ 07632
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"), and 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"), and 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): G50004103
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 900,000 Shares. The amount consists of (A) 216,000 Shares held for the account of Constellation Master Fund; (B) 153,000 Shares held for the account of Lake Credit Fund; (C) 189,000 Shares held for the account of Structured Credit Fund; (D) 153,000 Shares held for the account of Xing He Master Fund; (E) 153,000 Shares held for the account of Alpha Star Fund; (F) 9,000 Shares held for the account of Capital Master Fund; and (G) 27,000 shares held for the account of Waterfront Series A Fund. The Shares held by the Magnetar Funds represent approximately 5.22% 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 5.22% of the total number of shares outstanding (based upon the information provided by the Issuer in Form 8K filed on June 12, 2026, there were approximately 17,250,000 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: 900,000
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 900,000
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 Partne

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.