Magnetar reports 1,000,000 shares (5.79%) of BIII

Black Spade Acquisition III Co. reports that Magnetar-related reporting persons each beneficially own 1,000,000 Class A ordinary shares.

Accepted by SEC EDGAR 05/13/2026 - 09:27 AM EDT Learn about SEC filing dates

Rhea-AI Filing Summary

Black Spade Acquisition III Co. reports that Magnetar-related reporting persons each beneficially own 1,000,000 Class A ordinary shares. As of March 31, 2026, that holding represents approximately 5.79% of the outstanding shares, based on a cited 17,250,000 shares outstanding figure from the issuer's Form 10-K.

The 1,000,000 shares are allocated across Magnetar funds as follows: 280,000 for Constellation Master Fund, 200,000 for Lake Credit Fund, 250,000 for Structured Credit Fund, 180,000 for Xing He Master Fund, 10,000 for Capital Master Fund, 40,000 for Waterfront Series A Fund, and 40,000 for Purpose Alternative Credit Fund - T. Shared voting and dispositive power over the 1,000,000 shares is disclosed.

Insights

Institutional Ownership Analyst

Magnetar group holds a meaningful single‑holder stake (5.79%) via pooled funds.

The filing shows each Reporting Person is deemed beneficial owner of 1,000,000 shares as of March 31, 2026, representing 5.79% of 17,250,000 shares outstanding (issuer's Form 10-K basis). Ownership is held across multiple Magnetar funds with shared voting and dispositive power.

Concentration in hedge‑fund managed accounts can create potential liquidity or coordination effects; subsequent filings would show any change in percent ownership or voting arrangements.

Corporate Governance Advisor

Shared voting power and multi-entity structure imply centralized control through Magnetar Financial and affiliates.

The document states Magnetar Financial is the investment adviser and Magnetar Capital Partners is the parent, with Supernova Management and Mr. Snyderman in governance roles. The filing discloses shared voting/dispositive power for the full 1,000,000 shares.

Governance implications depend on whether Magnetar exercises coordinated voting; future proxy disclosures or Section 13 filings would clarify any control intent.

Key Figures

Shares beneficially owned: 1,000,000 shares Percent of class: 5.79% Shares outstanding (issuer basis): 17,250,000 shares +3 more

6 metrics

Shares beneficially owned 1,000,000 shares held by each Reporting Person as of March 31, 2026

Percent of class 5.79% percentage of class based on 17,250,000 shares outstanding

Shares outstanding (issuer basis) 17,250,000 shares cited from issuer's Form 10-K filed March 6, 2026

Constellation Master Fund holdings 280,000 shares part of the 1,000,000 aggregate holding

Structured Credit Fund holdings 250,000 shares part of the 1,000,000 aggregate holding

Shared voting power 1,000,000 shares shared voting power reported by the Reporting Persons

Key Terms

beneficially owned, shared dispositive power, Rule 13d-3(d)(1)(i), Form 10-K reference

4 terms

beneficially owned regulatory

"As of March 31, 2026, each of Magnetar Financial... held 1,000,000 Shares."

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

shared dispositive power regulatory

"Shared Dispositive Power 1,000,000.00"

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

"represent approximately 5.79%... (calculated pursuant to Rule 13d-3(d)(1)(i))"

Form 10-K reference regulatory

"based upon the information provided by the Issuer in the Form 10-K filed on March 6, 2026"

FAQ

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

What stake does Magnetar report in BIII?

The filing states each Magnetar reporting person beneficially owns 1,000,000 shares, about 5.79% of BIII's class as of March 31, 2026, using the issuer's 17,250,000 shares outstanding figure from its Form 10-K.

How are the 1,000,000 shares allocated across Magnetar funds?

The shares are allocated as: 280,000 Constellation Master Fund, 200,000 Lake Credit Fund, 250,000 Structured Credit Fund, 180,000 Xing He Master Fund, 10,000 Capital Master Fund, and 40,000 each for Waterfront Series A and Purpose Alternative Credit Fund - T.

Who holds voting and investment power over these shares?

Magnetar Financial is disclosed as the investment adviser exercising voting and investment power over the Magnetar Funds' accounts; the filing shows shared voting and shared dispositive power of 1,000,000 shares for the reporting persons.

What is the reporting date and the outstanding share base used?

Beneficial ownership is reported as of March 31, 2026. The percent calculation cites approximately 17,250,000 shares outstanding per the issuer's Form 10-K filed on March 6, 2026.

Do the filings indicate sole control by any single Magnetar entity?

No. The filing discloses 0 sole voting and dispositive power and 1,000,000 shared voting and dispositive power across the reporting persons, reflecting a multi-entity advisory and control structure.

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

BLACK SPADE ACQUISITION III CO.

(Name of Issuer)

Class A ordinary shares, par value $0.0001

(Title of Class of Securities)

G1154S103

(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): G1154S103

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 1,000,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,000,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,000,000.00

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)

5.79 %

12

Type of Reporting Person (See Instructions)

IA, OO

SCHEDULE 13G

CUSIP Number(s): G1154S103

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 1,000,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,000,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,000,000.00

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)

5.79 %

12

Type of Reporting Person (See Instructions)

HC, PN

SCHEDULE 13G

CUSIP Number(s): G1154S103

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 1,000,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,000,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,000,000.00

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)

5.79 %

12

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13G

CUSIP Number(s): G1154S103

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 1,000,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,000,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,000,000.00

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)

5.79 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: BLACK SPADE ACQUISITION III CO.
(b)	Address of issuer's principal executive offices: The Centrium, Suite 2902, 29/F, 60 Wyndham Street, Hong Kong, K3 00000
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 Lake Credit Fund LLC ("Lake Credit Fund"), Purpose Alternative Credit Fund - T LLC ("Purpose Alternative Credit Fund - T"), 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): G1154S103
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 March 31, 2026, each of Magnetar Financial, Magnetar Capital Partners, Supernova Management and Mr. Snyderman held 1,000,000 Shares. The amount consists of (A) 280,000 Shares held for the account of Constellation Master Fund; (B) 200,000 Shares held for the account of Lake Credit Fund; (C) 250,000 Shares held for the account of Structured Credit Fund; (D) 180,000 Shares held for the account of Xing He Master Fund; (E) 10,000 Shares held for the account of Capital Master Fund; (F) 40,000 shares held for the account of Waterfront Series A Fund; and (G) 40,000 Shares held for the account Purpose Alternative Credit Fund - T. The Shares held by the Magnetar Funds represent approximately 5.79% 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 March 31, 2026, each of the Reporting Persons were deemed to be the beneficial owner constituting approximately 5.79% of the total number of shares outstanding (based upon the information provided by the Issuer in the Form 10-K filed on March 6, 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: 1,000,000
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 1,000,000
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:	05/13/2026

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:	05/13/2026

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:	05/13/2026

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:	05/13/2026

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 May 13, 2026, among the Reporting Persons. 99.2 Power of Attorney, dated as of December 22, 2022 filed by the Reporting Persons on May 13, 2026.