[SCHEDULE 13G] Blue Water Acquisition Corp. III Unit. SEC Filing

Rhea-AI Filing Summary

Magnetar Financial LLC and affiliates filed a Schedule 13G reporting passive ownership of 1,500,000 Class A ordinary shares of Blue Water Acquisition Corp. III (ticker BLUWU) as of 30 Jun 2025. The stake equals 5.77 % of the 25.983 million shares outstanding, meeting the 5 % threshold that triggers Section 13 reporting. The shares are spread across eight Magnetar-managed funds, led by Constellation Master Fund (330 k) and Lake Credit Fund (270 k). Magnetar Financial, Magnetar Capital Partners LP, Supernova Management LLC and manager David J. Snyderman hold shared voting and dispositive power over the entire position; none possesses sole authority. Filed under Rule 13d-1(b) as an investment adviser/holding company, the disclosure states the position is held in the ordinary course of business and not for control purposes. A joint filing agreement and powers of attorney are included.

Positive

• Institutional endorsement: Magnetar’s 5.77 % stake introduces a sophisticated investor, potentially improving market perception and liquidity.

Negative

• None.

Insights

Portfolio Manager

TL;DR: Hedge fund Magnetar now owns 5.8 % of BLUWU; passive stake, no control intent.

The filing signals that a sophisticated multi-strategy manager accumulated a non-activist position in this SPAC. While the 5.77 % holding is notable, it remains below levels usually associated with activism. Magnetar’s shared voting/dispositive power and 13G (vs. 13D) status reinforce the passive intent. For investors, the key takeaway is the presence of institutional demand, which may enhance float stability but does not alter governance. Impact on valuation or deal prospects is modest; therefore the disclosure is neutral in fundamental terms.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Blue Water Acquisition Corp. III

(Name of Issuer)

Class A ordinary shares, par value $0.0001

(Title of Class of Securities)

G3730H122

(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. G3730H122

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 1,500,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,500,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,500,000.00

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)

5.77 %

12

Type of Reporting Person (See Instructions)

IA, OO

SCHEDULE 13G

CUSIP No. G3730H122

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 1,500,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,500,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,500,000.00

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)

5.77 %

12

Type of Reporting Person (See Instructions)

HC, PN

SCHEDULE 13G

CUSIP No. G3730H122

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 1,500,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,500,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,500,000.00

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)

5.77 %

12

Type of Reporting Person (See Instructions)

HC, OO

SCHEDULE 13G

CUSIP No. G3730H122

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 1,500,000.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,500,000.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,500,000.00

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)

5.77 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Blue Water Acquisition Corp. III
(b)	Address of issuer's principal executive offices: 15 E. PUTNUM AVENUE, SUITE 363 GREENWICH, CT, 06830
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"), 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 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 No.: G3730H122
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 1,500,000 Shares. The amount consists of (A) 330,000 Shares held for the account of Constellation Master Fund; (B) 270,000 Shares held for the account of Lake Credit Fund; (C) 195,000 Shares held for the account of Structured Credit Fund; (D) 255,000 Shares held for the account of Xing He Master Fund; (E) 180,000 Shares held for the account of Alpha Star Fund; (F) 150,000 Shares held for the account of Purpose Credit Fund; (G) 90,000 Shares held for the account of SC Fund; and (H) 30,000 Shares held for the account Waterfront Series A Fund. The Shares held by the Magnetar Funds represent approximately 5.77% 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 5.77% of the total number of shares outstanding (based upon the information provided by the Issuer in its prospectus filed with the SEC on June 11, 2025, there were approximately 25,983,000 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: 1,500,000
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 1,500,000
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

Why did Magnetar file a Schedule 13G on BLUWU?

Because its funds collectively crossed the 5 % ownership threshold, requiring disclosure under SEC Rule 13d-1(b).

How many BLUWU shares does Magnetar control?

Magnetar reports 1,500,000 Class A shares, representing 5.77 % of outstanding stock.

Does Magnetar intend to influence Blue Water Acquisition Corp. III’s control?

No. The filing states the shares are held in the ordinary course of business with no intent to change or influence control.

Which Magnetar fund holds the largest BLUWU position?

Magnetar Constellation Master Fund with 330,000 shares.

What voting power does Magnetar have over its BLUWU shares?

It has shared voting and dispositive power over all 1,500,000 shares; sole power is zero.

When was the ownership position measured?

Ownership data is as of June 30, 2025.