Company: SBXD
Filing Date: 2025-08-07
Form Type: 425
Source: 0001104659-25-074863
Chunk: 0

Company: SilverBox Corp IV
Filing Date: 2025-08-07
Form: 425
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): August 6, 2025

SILVERBOX CORP IV

(Exact name of registrant as specified in its charter)</div>

| Cayman                       
 Islands                      |     | 001-42214   |     | N/A                |
| (State or other jurisdiction 
 of incorporation)            |     | -Commission 
 File Number |     | -IRS Employer      
 Identification No. |

<div align='center'>8701 Bee Cave Road East Building, Suite 310 Austin,TX 78746

(Address of principal executive
offices, including zip code)

Registrant’s telephone number, including area code: (512) 575-3637

Not Applicable

(Former name or former address, if changed since last report)</div>

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

| x | Written communications pursuant to                              
 Rule 425 under the Securities Act (17 CFR 230.425)              |
| ¨ | Soliciting material pursuant to Rule 14a-12                     
 under the Exchange Act (17 CFR 240.14a-12)                      |
| ¨ | Pre-commencement communications pursuant to Rule 14d-2(b) under 
 the Exchange Act (17 CFR 240.14d-2(b))                          |
| ¨ | Pre-commencement communications pursuant to Rule 13e-4(c) under 
 the Exchange Act (17 CFR 240.13e-4(c))                          |

Securities registered pursuant to Section 12(b) of the Act:

| Title                                                                                                                                           
 of each class                                                                                                                                   |     | Trading   
 Symbol(s) |     | Name                        
 of each exchange            
 on which registered         |
| Units, each consisting of one Class A ordinary share, $0.0001 par value, and one-third of one redeemable warrant                                |     | SBXD.U    |     | New York Stock Exchange LLC |
| Class A ordinary shares included as part of the units                                                                                           |     | SBXD      |     | New York Stock Exchange LLC |
| Rede