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FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Issuer

Pursuant to Rule 13a-16 or 15d-16 of

the Securities Exchange Act of 1934

For the month of July 2017

Commission File Number: 001-12518

Banco Santander, S.A.

(Exact name of registrant as specified in its charter)

Ciudad Grupo Santander

28660 Boadilla del Monte (Madrid) Spain

(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    

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Banco Santander, S.A.

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Item 1

MATERIAL FACT

In relation to the “Third Issuance of Internationalisation Bonds”, with ISIN code ES0313900401, carried out by Banco Santander, S.A. (The Issuer), for one hundred and eighty million (180,000,000) US dollars (the Third Issuance), and the Securities Note of which was entered in the records of the Spanish National Securities Market Commission on 31 March 2016 with official registration number 97428, Banco Santander, S.A. hereby announces that it will proceed with the partial redemption and cancellation of the Internationalisation Bonds included in the Third Issuance on 12 July 2017 (the “Early Redemption Date”). The current unit nominal value is USD 118,750.

The partial redemption will be carried out on a pro rata basis, by reducing the unit nominal value of the internationalisation bonds by USD 22,500, such that, once the partial redemption has been made, the unit nominal value will be USD 96,250.

Likewise, on the Early Redemption Date, the Issuer will pay the holders of the internationalisation bonds included in the Third Issuance the amount equivalent to the interest earned, i.e. the amount corresponding to the interest earned, from the day the last quarterly interest payment was made until the Early Redemption Date, pursuant to the Securities Note.

In light of the foregoing, the securities redemption tables in item 4.9 of the Securities Note will now be as follows:

Published as a material fact for relevant purposes.

Boadilla del Monte, 11 July 2017

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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.