Company: CIB
Filing Date: 2025-05-16
Form Type: 8-K12B
Source: 0001193125-25-121701
Chunk: 0

Company: Grupo Cibest S.A.
Filing Date: 2025-05-16
Form: 8-K12B
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

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

THE SECURITIES EXCHANGE ACT OF 1934

For the month of May, 2025

Commission File Number: None

Grupo Cibest S.A.

(Translation of registrant’s name into English)

Cra. 48 

# 26-85
Medellín, Colombia

(Address of principal executive offices)

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-F ☒ Form 40-F ☐

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.

| Date May 16, 2025 |     | GRUPO CIBEST S.A. 
 (Registrant)      
 By:               |     | /s/ Mauricio Botero Wolff              |
|:------------------|:----|:------------------|:----|:---------------------------------------|
|                   |     | Name:             |     | Mauricio Botero Wolff                  |
|                   |     | Title:            |     | Vice President of Strategy and Finance |

2

Completion of Corporate Structure Changes Effective as of May 16, 2025, Bancolombia S.A. (“Bancolombia”) and its affiliates completed the previously announced modification to the corporate structure of Bancolombia pursuant to which Grupo Cibest S.A. (“Grupo Cibest”) was established as the holding company for Bancolombia and its affiliates and certain related corporate transactions were undertaken (the “Corporate Structure Changes”). In connection with the Corporate Structure Changes, each common share of Bancolombia was exchanged for one common share of Grupo Cibest and each preferred share of Bancolombia was exchanged for one preferred share of Grupo Cibest, except for shares of Bancolombia held by Grupo Cibest. Holders of each American depositary share representing four preferred shares of Bancolombia (a “Bancolombia ADS”) will receive one new American depositary share representing four preferred shares of Grupo Cibest (a “Grupo Cibest ADS”).