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 September, 2026
Commission File Number: 001-34476
BANCO SANTANDER (BRASIL) S.A.
(Exact name of registrant as specified in its charter)
Avenida Presidente Juscelino Kubitschek, 2041 and 2235
Bloco A – Vila Olimpia
São Paulo, SP 04543-011
Federative Republic of Brazil
(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 ___X___ 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 ___X____
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 ___X____
Indicate by check mark whether by furnishing the information contained in this Form, the Registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934:
Yes _______ No ___X____
If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): N/A

BANCO SANTANDER (BRASIL) S.A.
Publicly Traded Company with Authorized Capital
CNPJ/MF No. 90.400.888/0001-42
NIRE 35,300,332,067
MATERIAL FACT
BANCO SANTANDER (BRASIL) S.A. ("Santander
Brasil" or "Company"), in compliance with the provisions of CVM Resolution No. 44/21 and Article 157, Paragraph
4, of Law No. 6,404/76, and in addition to the material fact disclosed on July 30, 2026 (“July 30, 2026, Material Fact”),
hereby informs its shareholders and the market in general, in connection with the intended voluntary exchange public offer in Brazil (“Brazilian
Exchange Offer”) and the exchange offer in the United States (“U.S. Exchange Offer” and, together with the
Brazilian Exchange Offer, the “Exchange Offers”), announced by Banco Santander, S.A. (“Offeror”
or “Banco Santander”) and detailed by the Company in the Material Fact issued on July 30, 2026 that the following filings
were carried out by Banco Santander on this date:
| i. | the request for registration of Banco
Santander as a foreign issuer (publicly-held company – category A) with the Brazilian Securities and Exchange Commission ("CVM"); |
| ii. | the request for registration of Banco
Santander’s Brazilian Depositary Receipts Program with the CVM; |
| iii. | the admission request of Banco Santander's
Brazilian Depositary Receipts (“BDRs”) to trading on B3 S.A. – Brasil, Bolsa, Balcão ("B3"); |
| iv. | the request for registration of the
Brazilian Exchange Offer with the CVM and B3; and |
| v. | the filing of a registration statement
on Form F-4 with the U.S. Securities and Exchange Commission (the “SEC”). The Form F-4 has not yet been declared effective
by the SEC. |
In addition, the Company received today the appraisal
report of Santander Brasil and Banco Santander to be used for purposes of the Brazilian Exchange Offer, prepared by UBS BB Corretora de
Câmbio, Títulos e Valores Mobiliários S.A. (“Appraisal Report”).
The Appraisal Report was made available simultaneously
with the disclosure of this Material Fact through the CVM’s and B3’s IPE System, and disclosed on the Company’s website
(https://www.santander.com.br/ri/), pursuant to Article 18 of CVM Resolution No. 215, dated October
29, 2024.
This Material Fact is for informational purposes
only. This Material Fact shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there
be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification
under the securities laws of any such jurisdiction.
Santander Brasil will keep its shareholders and
the market informed of any new relevant developments related to the Exchange Offers, in accordance with applicable regulations.
São Paulo, September 21, 2026
Carlos Ignacio Muñiz Gonzalez Blanch
Executive Vice President and Chief Investor Relations
Officer
IMPORTANT INFORMATION FOR INVESTORS REGARDING THE PROPOSED TRANSACTION
In connection with the proposed transaction, Banco Santander
has filed with the SEC a Registration Statement on Form F-4 that includes a prospectus and offer to exchange. Banco Santander has also
filed with the CVM a Tender Offer Notice (Edital de Oferta Pública de Aquisição) in connection with the transaction
and the prospective offer as required under applicable law. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE REGISTRATION STATEMENT,
PROSPECTUS, OFFER TO EXCHANGE, TENDER OFFER NOTICE AND ALL OTHER RELEVANT DOCUMENTS THAT HAVE BEEN FILED WITH THE SEC AND THE CVM REGARDING
THE PROPOSED TRANSACTION BECAUSE THEY CONTAIN IMPORTANT INFORMATION.
All such documents filed with the SEC are available free
of charge at the SEC’s website at www.sec.gov and through the CVM’s website at www.cvm.gov.br.
The information included in the Form F-4 filed with the
SEC and in the draft tender offer notice filed with the CVM and B3 is preliminary and may be changed. The definitive terms and conditions
of the Exchange Offers and other relevant information will be included in the definitive offer documentation prepared and published in
due course upon formal launch once announced conditions to the commencement of the Exchange Offers have been fulfilled, which will complement,
update and supersede the information included therein. Such documents are subject to, and must be read in conjunction with, all other
publicly available information, including, where relevant, any fuller disclosure document published by Banco Santander. Any person at
any time making any investment decision must do so only on the basis of such person’s own judgment as to the merits or the suitability
of the securities for its purpose and only on such information as is contained in the definitive offer documentation having taken all
such professional or other advice as it considers necessary or appropriate in the circumstances and not in reliance on the information
contained in other documents. No investment activity should be undertaken on the basis of the information contained herein or in such
documents. In making such documents available Banco Santander gives no advice and makes no recommendation to buy, sell or otherwise deal
in shares in Banco Santander or Santander Brasil or in any other securities or investments whatsoever.
This document is not an offer of securities for sale into
the United States, Brazil, Spain, the United Kingdom, Poland, Mexico or elsewhere. No offering of securities shall be made in the United
States except pursuant to registration under the U.S. Securities Act of 1933, as amended, or an exemption therefrom, and no offering of
securities shall be made in Brazil, Spain, the United Kingdom, Poland or Mexico except pursuant to applicable law.
Forward-Looking Statements
This communication contains “forward-looking statements,”
which may be identified by words like expect, project, anticipate, should, intend, probability, risk, target, goal, objective, estimate,
future and similar expressions and include, but are not limited to, statements that are predictive in nature and depend upon or refer
to future events, conditions, circumstances or the future performance of Banco Santander or Santander Brasil or their respective affiliates,
including as a result of the implementation of the transactions described herein. These statements are based on management’s current
expectations and are inherently subject to uncertainties and changes in circumstance and a number of risks, uncertainties and other important
factors may cause actual developments and results to differ materially from current expectations.
Risks and uncertainties include, among other things:
| · | general economic or industry conditions (e.g., an economic
downturn; higher volatility in the capital markets; inflation; deflation; changes in demographics, consumer spending, investment or saving
habits; and the effects of the armed conflicts in Ukraine and the Middle East, or the outbreak of public health emergencies in the global
economy) in areas where we have significant operations or investments; |
| · | exposure to operational risks, including cyberattacks, data
breaches, data losses and other security incidents; |
| · | exposure to market risks (e.g., risks from interest rates,
foreign exchange rates, equity prices and new benchmark indices); |
| · | potential losses from early loan repayment, collateral depreciation
or counterparty risk; |
| · | political instability in Spain, the UK, other European countries,
Latin America and the US; |
| · | changes in monetary, fiscal and immigration policies and trade
tensions, including the imposition of tariffs and retaliatory responses; |
| · | legislative, regulatory or tax changes (including regulatory
capital and liquidity requirements) and greater regulation prompted by financial crises; |
| · | acquisitions, integrations, divestitures and challenges arising
from deviating management’s resources and attention from other strategic opportunities and operational matters; |
| · | reputational risk and potential adverse reactions of stakeholders,
including adverse effects on the market price of our securities; |
| · | climate-related conditions, regulations, targets and weather
events; |
| · | uncertainty over the scope of actions that may be required
by us, governments and other to achieve goals relating to climate, environmental and social matters, as well as the evolving nature of
underlying science and potential conflicts and inconsistencies among governmental standards and regulations; |
| · | our own decisions and actions, including those affecting or
changing our practices, operations, priorities, strategies, policies or procedures; and |
| · | changes affecting our access to liquidity and funding on acceptable
terms, especially due to credit spread shifts or credit rating downgrade for the entire Santander Group or core subsidiaries. |
Additionally, important factors that could cause Banco Santander’s
and/or Santander Brasil’s actual results, financial condition and achievements to differ materially from those indicated in these
forward-looking statements include, in addition to those set forth in Banco Santander’s and Santander Brasil’s
filings with the SEC and the CVM, as applicable:
| · | risks related to the proposed transaction, including uncertainties
as to whether certain statutory relief under the U.S. securities laws will be granted, the risk that the conditions to commencement and/or
consummation of the proposed transaction are not received or satisfied on a timely basis or at all, and the risk of Santander Brasil shareholders
not tendering their securities in the proposed transaction or otherwise not supporting the terms of the proposed transaction; |
| · | the expected timing and likelihood of completion of the transaction,
including the timing, receipt and terms and conditions of any required regulatory or shareholder approvals; |
| · | disruption to the parties’ businesses as a result of
the announcement and pendency of the proposed transaction; |
| · | the risk that matters relating to the transaction could have
adverse effects on the market price of the securities of Banco Santander or Santander Brasil; |
| · | the risk that the transaction could have an adverse effect
on the ability of Banco Santander or Santander Brasil to retain customers and retain and hire key personnel and maintain relationships
with their suppliers and customers; |
| · | the possibility that the proposed transaction may be more
expensive to complete than anticipated, including as a result of unexpected factors or events; |
| · | the dilution caused by Banco Santander’s issuance of
additional ordinary shares and corresponding American depositary shares or BDRs, each representing the right to receive one of its ordinary
shares, or , in connection with the proposed transaction; and |
| · | compliance with regulatory requirements. |
All such factors are difficult to predict and are beyond
Banco Santander’s and Santander Brasil’s control, including those other risks and uncertainties discussed in (i) Banco Santander’s
filings with the SEC, including the “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements”
sections of Banco Santander’s most recent annual report on Form 20-F and subsequent 6-Ks filed with, or furnished to, the SEC and
(ii) Santander Brasil’s filings with the SEC and the CVM, as applicable, including the “Risk Factors” and “Forward-Looking
Statements” sections of Santander Brasil’s most recent annual report on Form 20-F and subsequent 6-Ks filed with, or furnished
to, the SEC and most recent Formulário de Referência filed with the CVM.
You can obtain copies of Banco Santander’s and Santander
Brasil’s filings, as applicable, with the SEC and the CVM for free at the SEC’s website (www.sec.gov) or at the CVM’s
website (ww.cvm.gov.br). Other factors that may cause actual results to differ materially include those that are set forth in the Registration
Statement on Form F-4 and the related Offer to Exchange/Prospectus, the Tender Offer Notice, and those that will be set forth in the Solicitation/Recommendation
Statement on Schedule 14D-9 and other tender offer documents to be filed by Banco Santander and Santander Brasil. All forward-looking
statements in this communication are qualified in their entirety by this cautionary statement.
Our forward-looking statements speak only as at the date
of this communication and are informed by the knowledge, information and views available as at the date of this communication. Banco Santander
is not required to update or revise any forward-looking statements, regardless of new information, future events or otherwise.
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, thereto duly authorized.
Date: September 21, 2026
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Banco Santander (Brasil) S.A. |
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By: |
/S/ Reginaldo Antonio Ribeiro
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Reginaldo Antonio Ribeiro Officer without specific designation
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By: |
/S/ Carlos Ignacio Muñiz Gonzalez Blanch
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Carlos Ignacio Muñiz Gonzalez Blanch Vice - President Executive Officer
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