W. R. Berkley holds 5.9% of SilverBox Corp IV (SBXD)

Rhea-AI Filing Summary

W. R. Berkley Corporation and its subsidiary Berkley Insurance Company report beneficial ownership of 1,211,674 Class A ordinary shares of SilverBox Corp IV, representing 5.9% of the class.

The shares carry shared voting and dispositive power, with no sole power reported. The securities were acquired and are held in the ordinary course of business and are not intended to change or influence control of SilverBox Corp IV.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

SILVERBOX CORP IV

(Name of Issuer)

Class A ordinary shares, par value $0.0001 per share

(Title of Class of Securities)

G81354105

(CUSIP Number)

12/31/2025

(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. G81354105

1

Names of Reporting Persons

W. R. Berkley Corporation

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 1,211,674.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,211,674.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,211,674.00

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)

5.9 %

12

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13G

CUSIP No. G81354105

1

Names of Reporting Persons

Berkley Insurance Company

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 1,211,674.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,211,674.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,211,674.00

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)

5.9 %

12

Type of Reporting Person (See Instructions)

CO, IC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: SILVERBOX CORP IV
(b)	Address of issuer's principal executive offices: 8701 Bee Cave Road, East Building, Suite 310, Austin, TX, 78746
Item 2.
(a)	Name of person filing: W. R. Berkley Corporation
(b)	Address or principal business office or, if none, residence: 475 Steamboat Road Greenwich, CT 06830
(c)	Citizenship: US
(d)	Title of class of securities: Class A ordinary shares, par value $0.0001 per share
(e)	CUSIP No.: G81354105
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: 1,211,674
(b)	Percent of class: 5.9 %
(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: 1,211,674
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 1,211,674
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.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. See Exhibit 99.1
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.

W. R. Berkley Corporation

Signature:	/s/ Richard M. Baio
Name/Title:	Richard M. Baio/Executive Vice President and Chief Financial Officer
Date:	02/10/2026

Berkley Insurance Company

Signature:	/s/ Richard M. Baio
Name/Title:	Richard M. Baio/Executive Vice President and Treasurer
Date:	02/10/2026

FAQ

What percentage of SilverBox Corp IV (SBXD) does W. R. Berkley report owning?

W. R. Berkley reports beneficial ownership of 5.9% of SilverBox Corp IV’s Class A shares. This percentage is based on 1,211,674 shares that the reporting persons collectively beneficially own, giving them a disclosed minority but more than five percent interest in the company.

How many SilverBox Corp IV Class A shares does W. R. Berkley beneficially own?

W. R. Berkley reports beneficial ownership of 1,211,674 Class A ordinary shares. These shares are held with shared voting and shared dispositive power between W. R. Berkley Corporation and Berkley Insurance Company, with no sole voting or sole dispositive authority reported for either entity.

What type of security in SBXD is reported by W. R. Berkley on this Schedule 13G?

The reported security is SilverBox Corp IV Class A ordinary shares, par value $0.0001 per share. The filing identifies this specific class as the subject of beneficial ownership, using CUSIP number G81354105 to precisely reference the securities covered.

Does W. R. Berkley intend to influence control of SilverBox Corp IV with this stake?

No, W. R. Berkley states the shares were acquired and are held in the ordinary course of business. It explicitly certifies they were not acquired and are not held for changing or influencing control, nor in connection with any transaction having that purpose or effect.

Who signed the SilverBox Corp IV (SBXD) beneficial ownership statement for W. R. Berkley?

Richard M. Baio signed the statement for W. R. Berkley entities. He signed once as Executive Vice President and Chief Financial Officer, and again as Executive Vice President and Treasurer, each signature dated 02/10/2026, certifying the completeness and accuracy of the information.

What voting and dispositive powers does W. R. Berkley report over SilverBox Corp IV shares?

W. R. Berkley reports zero sole voting or dispositive power and 1,211,674 shares of shared power in each case. Both W. R. Berkley Corporation and Berkley Insurance Company list the same figures for shared voting and shared dispositive authority over the Class A ordinary shares.