Company: SBXD
Filing Date: 2025-09-04
Form Type: 425
Source: 0001104659-25-087514
Chunk: 0

Company: SilverBox Corp IV
Filing Date: 2025-09-04
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): September 3, 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 |     | -I.R.S. Employer   
 Identification No. |

| 1250                            
 S. Capital of Texas Highway,    
 Building                        
 2, Suite 285                    
 Austin,                         
 TX                              |     |     78746 |
| (Address                        
 of Principal Executive Offices) |     | -Zip Code |

| (512)                                  
 575-3637                               |
| (Registrant’s                          
 Telephone Number, Including Area Code) |

| N/A                                      |
| (Former                                  
 Name or Former Address, if Changed Since 
 Last Report)                             |

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