UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

Tender Offer Statement under Section 14(d)(1) or 13(e)(1)
of the Securities Exchange Act of 1934

(Amendment No. 4)

Banco Santander México, S.A., Institución De Banca Múltiple, Grupo Financiero Santander México

(Name of Subject Company (Issuer))

Banco Santander, S.A.

(Names of Filing Persons (offerors))

Series B Shares, par value Ps.3.780782962*

American Depositary Shares (each of which represents five Series B Shares)

(Title of Class of Securities)

MX41BS060005 (Series B Shares)

(ISIN Number of Class of Securities)

05969B103 (American Depositary Shares Representing Series B Shares)

(CUSIP Number of Class of Securities)

Banco Santander, S.A.

New York Branch

45 E. 53rd Street

New York, New York 10022

Attn: Mercedes Pacheco, Managing Director and Senior Legal Counsel

Telephone: (212) 350-3500

(Name, address and telephone number of person authorized to receive notices and communications on behalf of the filing person)

With copies to:

Michael J. Willisch, Esq.

Davis Polk & Wardwell LLP

Paseo de la Castellana, 41

Madrid, Spain 28046

Tel: +34 91 768 9600

Check the appropriate boxes below to designate any transactions to which the statement relates:

Check the following box if the filing is a final amendment reporting the results of the tender offer: ☐

If applicable, check the appropriate box(es) below to designate the appropriate rule provision(s) relied upon:

This Amendment No. 4 (this “Amendment No. 4”) amends and supplements the Tender Offer Statement on Schedule TO filed by Banco Santander, S.A., a company organized under the laws of the Kingdom of Spain (the “Purchaser”) with the U.S. Securities and Exchange Commission (the “SEC”) on February 7, 2023 (as amended and supplemented by Amendment No. 1, dated March 6, 2023, Amendment No. 2, dated April 10, 2023, Amendment No. 3, dated April 13, 2023, Amendment No. 4 and as further amended or supplemented from time to time, the “Schedule TO”).

The Schedule TO relates to the offer by Purchaser to acquire all the issued and outstanding (i) Series B shares of Banco Santander México, S.A., Institución De Banca Múltiple, Grupo Financiero Santander México, a company incorporated in United Mexican States (the “Company”), par value Ps.3.78078296 per share (the “Series B Shares”), and (ii) American Depositary Shares (each of which represents five Series B Shares) of the Company (the “ADSs,” and together with the Series B Shares, the “Shares”), in each case other than any Series B Shares or ADSs owned directly or indirectly by Purchaser, for Ps.24.52 in cash per Series B Share, or the U.S. dollar equivalent of Ps.122.6 in cash per ADS, without interest, upon the terms, and subject to the conditions, set forth in the Offer to Purchase, dated February 7, 2023 (as it may be amended or supplemented from time to time, the “Offer to Purchase”), a copy of which is attached to the Schedule TO as Exhibit (a)(1)(i), and the related Acceptance for B Shares and ADS Letter of Transmittal (as both defined in the Offer to Purchase), copies of which are attached to the Schedule TO as Exhibits (a)(1)(ii) and (a)(1)(iii), respectively.

Except as otherwise set forth in this Amendment No. 4, the information set forth in the Schedule TO remains unchanged and is incorporated herein by reference to the extent relevant to the items in this Amendment No. 4. Capitalized terms used but not defined herein have the meanings ascribed to them in the Schedule TO.

Items 1 through 9 and Item 11.

The information contained in the Offer to Purchase and Items 1 through 9 and Item 11 of the Schedule TO, to the extent such Items incorporate by reference the information contained in the Offer to Purchase, are hereby amended and supplemented by adding the following text thereto:

“On May 12, 2023, the registration of the Company’s Series B Shares with the Mexican National Securities Registry of the CNBV was cancelled. Pursuant to the Mexican Securities Market Law, Purchaser and the Company have incorporated the Repurchase Trust. Holders of Series B Shares that remain outstanding following completion of the Offers will have the right, but not the obligation, to sell their Series B Shares to the Repurchase Trust at any time during a period of six (6) months from May 12, 2023 for Ps.24.52 per Series B Share, i.e., the same cash consideration that they would have received during the Mexican Offer in respect of their Series B Shares. The Statutory Sell-out procedure is being treated as a six-month subsequent offering period to the U.S. Offer pursuant to Rule 14d-11 of the Exchange Act. Under Mexican law and regulations, the Statutory Sell-out is not being treated as a tender offer in Mexico or a subsequent offering period of the Mexican Offer.”

SIGNATURES

After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

EXHIBIT INDEX

* Previously filed.