Company: CIB
Filing Date: 2025-12-19
Form Type: 6-K
Source: 0002058897-25-000055
Chunk: 0

Company: Grupo Cibest S.A.
Filing Date: 2025-12-19
Form: 6-K
Chunk 0
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### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549
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#### FORM 6-K
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### REPORT OF FOREIGN PRIVATE ISSUER

#### PURSUANT TO RULE 13a-16 OR 15d-16 OF

#### THE SECURITIES EXCHANGE ACT OF 1934

#### For the month of December, 2025

#### Commission File Number 001-42656
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#### Grupo Cibest S.A.
<div align='center'>(Translation of registrant’s name into English)

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#### Cra. 48 # 26-85

#### Medellín, Colombia
<div align='center'>(Address of principal executive offices)

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Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

| Form 20-Fþ |     | Form 40-Fo |

| 1 |

### SIGNATURE
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

|                        |     | Grupo CIBEST S.A. 
 (Registrant)      |     |                                        |
| Date December, 18,2025 |     | By:               |     | /s/ MAURICIO BOTERO WOLFF.             |
|                        |     | Name:             |     | Mauricio Botero Wolff                  |
|                        |     | Title:            |     | Vice President of Strategy and Finance |

December 18, 2025

Medellin, Colombia

<div align='center'>GRUPO CIBEST S.A. ANNOUNCES AGREEMENT FOR THE SALE OF BANISTMO S.A.</div>

Grupo Cibest S.A. (“Grupo Cibest”) informs that today it entered into a promise to purchase shares agreement with Inversiones Cuscatlán Centroamérica S.A. for the sale of 100% of the shares of Banistmo S.A. (“Banistmo”).

Banistmo began operations in 1973 and is one of Grupo Cibest’s financial entities located in the Republic of Panama, after being acquired in October 2013.Banistmo