KB 6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 6-K

REPORT OF FOREIGN PRIVATE ISSUER

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

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of July 2026

Commission File Number: 000-53445

KB Financial Group Inc.

(Translation of registrant’s name into English)

26, Gukjegeumyung-ro 8-gil, Yeongdeungpo-gu, Seoul 07331, Korea

(Address of principal executive office)

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 ☐

Changes in the Number of Shares Owned by the Largest Shareholder of KB Financial Group Inc.

On July 21, 2026, KB Financial Group Inc. (“KB Financial Group”) reported that the number of shares owned by its largest shareholder, the Korean National Pension Service, had decreased from 33,460,006 shares of common stock, representing 8.97% of 372,850,455 total shares of KB Financial Group as of May 8, 2026, to 32,734,500 shares of common stock, representing 9.23% of 354,687,734 total shares based on the shareholder registry of KB Financial Group as of June 30, 2026.

SIGNATURES

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.