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FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Private Issuer

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

of the Securities Exchange Act of 1934

For the month of May, 2017

Commission File Number: 001-09531

Telefónica, S.A.

(Translation of registrant’s name into English)

Distrito Telefónica, Ronda de la Comunicación s/n,

28050 Madrid, Spain

3491-482 87 00

(Address of principal executive offices)

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  ☐

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 the 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): N/A

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Telefónica, S.A.

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FINANCIAL HIGHLIGHTS

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Comments from José María Álvarez-Pallete, Executive Chairman:

“First quarter results reflected a further step forward in our business model, which is focused on the pursuit of sustainable growth. The differential quality of our asset portfolio enables us to offer differential services, which translated into improvements in our results; in particular: i) the growth in main financial metrics, including the positive impact of foreign exchange rates in the quarter; ii) the savings obtained from synergy capture and process simplification; and iii) the strengthening of our balance sheet and the strong free cash flow growth, 9x higher vs. January-March 2016. In addition, we have announced the launch of AURA, a new, more innate and simple customer relationship model, a pioneer in the area of cognitive intelligence.

At the same time, the results are aligned with our expectations and allow us to reiterate the guidance set for 2017”.

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TELEFÓNICA

SELECTED FINANCIAL DATA

Unaudited figures (Euros in millions)

- Reconciliation included in the excel spreadsheets.

Notes:

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DISCLAIMER

This document may contain forward-looking statements regarding intentions, expectations or forecasts related to the Telefónica Group (hereinafter, the “Company” or “Telefónica”). These statements may include financial forecasts and estimates based on assumptions or statements regarding plans, objectives and expectations that make reference to different matters, such as the customer base and its evolution, growth of the different business lines and of the global business, the market share, possible acquisitions, divestitures or other transactions, Company results and other aspects related to the activity and situation of the Company.

The forward-looking statements can be identified, in certain cases, through the use of words such as “expectation”, “anticipation”, “purpose”, “belief” or similar expressions, or the corresponding negative forms, or through the own predictive nature of all issues referring to strategies, plans or intentions. These forward-looking statements or forecasts reflect the current views of Telefónica with respect to future events, do not represent, by their own nature, any guarantee of future fulfilment, and are subject to risks and uncertainties that could cause the final developments and results to differ substantially from the ones put forward through these intentions, expectations or forecasts. These risks and uncertainties include those identified in the documents containing more comprehensive information filed by Telefónica before the different supervisory Authorities of the securities markets in which its shares are listed and, in particular, the Spanish National Securities Market Commission.

Except as required by applicable laws, Telefónica does not assume any obligation to publicly update these statements to adapt them to events or circumstances taking place after this document, including changes in the Company’s business, in its business development strategy or any other unexpected circumstance.

This document may contain summarized, non-audited or Non-GAAP financial information. The information contained herein should therefore be considered as a whole and in conjunction with all the public information regarding the Company available, including, if any, other documents released by the Company that may contain more detailed information.

In October 2015, the European Securities Markets Authority (ESMA) published guidelines on Alternative Performance Measures (APM), applicable to the regulated information published from July 3, 2016. Information and disclosure related to APM used in the present document are included in the Appendix. Moreover, recipients of this document are invited to read our consolidated financial statements and consolidated management report for 2016 submitted to the Spanish National Securities Market Commission.

Finally, it is hereby stated that neither this document or any of its contents constitutes an offer to purchase, sale or exchange any securities, a solicitation of any offer to purchase, sale or exchange of securities, or a recommendation or advice regarding any security.

For further information please refer to the information on 2017 first quarter financial results filed by the Company and also available on the Company’s website: www.telefonica.com

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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.