Company: HYAC-WT
Filing Date: 2025-10-14
Form Type: 8-K/A
Source: 0001104659-25-099332
Chunk: 0

Company: Haymaker Acquisition Corp. 4
Filing Date: 2025-10-14
Form: 8-K/A
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K /A

(Amendment No. 1)

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): October 9, 2025

HAYMAKER ACQUISITION CORP. 4

(Exact Name of Registrant as Specified in Charter)</div>

| Cayman Islands               |     | 001-41757   |     | 87-2213850         |
| (State or Other Jurisdiction 
 of Incorporation)            |     | -Commission 
 File Number |     | -IRS Employer      
 Identification No. |

| 324 Royal Palm Way, Suite 300-i                     
 Palm Beach, FL 33480                                |
| (Address of Principal Executive Offices) (Zip Code) |

<div align='center'>( 212) 616-9600

(Registrant’s Telephone Number, Including Area Code)

(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 and one-half of one redeemable warrant                      |     | HYACU     |     | The New York Stock Exchange |
| Class A ordinary shares, par value $0.0001 per share                                                             |     | HYAC      |