Fractional bonus shares sold for Itaú Unibanco (NYSE: ITUB)

Rhea-AI Filing Summary

Itaú Unibanco Holding S.A. explains how it is handling fractional shares created by a previous share bonus. These fractions were grouped and sold on B3 at an auction on February 24, 2026, totaling 198,581 book-entry shares, including 55,921 common shares and 142,660 preferred shares. The net proceeds were BRL 44.8730180388 per common share and BRL 48.1301186067 per preferred share. The funds will be made available on March 10, 2026 to eligible stockholders. Holders with updated registration details at the Company will receive deposits via Itaú Corretora de Valores S.A., while others will receive payment through B3 and their custody agents. Amounts for stockholders without up-to-date registration will remain available for 10 years.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Issuer Pursuant to Rule 13a-16 or 15d-16 of the Securities Exchange Act of 1934

For the month of March, 2026

Comission File Number: 001-15276

Itaú Unibanco Holding S.A.

(Exact name of registrant as specified in its charter)

Itaú Unibanco Holding S.A.

(Translation of Registrant’s Name into English)

Praça Alfredo Egydio de Souza Aranha, 100 - Torre Conceição

CEP 04344-902 São Paulo, SP, Brazil (Address of principal executive office)

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

Form 20-F ☒

Form 40-F ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Yes ☐

No ☒

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):

Yes ☐

No ☒

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes ☐

No ☒

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b):

82– __________________

EXHIBIT INDEX

99.1 ITAÚ UNIBANCO - Notice to Shareholders - Payment of fractions of shares resulting from the bonus share

.

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: March 03, 2026.

Itaú Unibanco Holding S.A.

By: /s/ Gustavo Lopes Rodrigues

Name: Gustavo Lopes Rodrigues

Title: Investor Relations Officer.

Notice to Stockholders Itaú Unibanco Holding S.A. (“Company”) announces to its stockholders, by supplementing the Material Fact disclosed on December 18, 2025, that the share fractions arising from the share bonus have been grouped in whole numbers and sold on B3 S.A. – Brasil, Bolsa, Balcão (“B3”) at the auction held on February 24, 2026. At this auction, 198,581 book-entry shares with no par value were sold, of which 55,921 common shares and 142,660 preferred shares, with the net amounts of BRL 44.8730180388 for each common share and BRL 48.1301186067 for each preferred share. These amounts will be available for 10 years1 to stockholders without up-to-date registration information from the date of payment to stockholders with up-to-date registration information. The proceeds of these fractions will be made available on March 10, 2026 to stockholders entitled to receive them, as follows: a) for stockholders registered in the Company's books whose registration information is up-to- date, proceeds will be deposited directly by Itaú Corretora de Valores S.A., the institution responsible for the Company's share bookkeeping, to the current account at the Financial Institution indicated in the stockholder's registration information. Any stockholders whose registration information is not updated should do so through the channels below: (i) App Íon (for shareholders who are Itaú account holders) – by following the route: My account > Update your registration information, and (ii) brick-and-mortar branch: hold individual taxpayer’s registry (CPF), identity card (RG), proof of residence and proof of bank domicile; and b) for other stockholders, payment will be made directly to B3, who will subsequently transfer these amounts to the stockholders included in their registrations, through their Custody Agents. São Paulo (SP), March 03, 2026. Gustavo Lopes Rodrigues Investor Relations Officer 1 According to article 205 of the Civil Code.

FAQ

What does Itaú Unibanco (ITUB) announce in this 6-K filing?

Itaú Unibanco announces the sale of fractional shares created by a past share bonus. These fractions were consolidated, auctioned on B3, and the resulting cash will be distributed to eligible stockholders according to their registration status and custody arrangements.

How many Itaú Unibanco (ITUB) fractional shares were sold and of which types?

A total of 198,581 book-entry shares with no par value were sold, including 55,921 common shares and 142,660 preferred shares. These came from fractional positions generated by the Company’s earlier share bonus credited to its stockholders.

What prices did Itaú Unibanco (ITUB) receive for the fractional shares?

The auction on B3 generated net amounts of BRL 44.8730180388 per common share and BRL 48.1301186067 per preferred share. These figures represent the net proceeds to be allocated proportionally to stockholders holding the original fractional positions.

When will Itaú Unibanco (ITUB) pay the proceeds from the fractional share sale?

The proceeds from selling the fractional shares will be made available on March 10, 2026. Stockholders entitled to receive them will be paid either via Itaú Corretora-deposited amounts or through B3 and their custody agents, depending on how their shares are registered.

How will Itaú Unibanco (ITUB) pay stockholders with updated registration information?

For stockholders recorded in the Company’s books with up-to-date registration, proceeds will be deposited directly by Itaú Corretora de Valores S.A. The money will go to the current account at the financial institution indicated in each stockholder’s registration details.

How can Itaú Unibanco (ITUB) stockholders with outdated registration data receive proceeds?

Stockholders with outdated information must update their registration through the Íon app for Itaú account holders or at a branch, presenting CPF, RG, proof of residence and bank domicile. The amounts will remain available for 10 years, as allowed under Brazilian Civil Code article 205.

How are Itaú Unibanco (ITUB) stockholders using B3 custody paid these proceeds?

For stockholders whose shares are held through B3, payment will be made to B3, which will then transfer the amounts via each investor’s Custody Agent. This route applies to holders not directly registered in the Company’s own shareholder records.

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