OIBRQ OI SA New (CE)

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

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:  1-15256

OI S.A.

(Exact Name as Specified in its Charter)

N/A

(Translation of registrant’s name into English)

Rua General Polidoro, No. 99, 5th floor/part – Botafogo

22280-001 Rio de Janeiro, RJ
Federative Republic of Brazil

(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:    ý       Form 40-F:   o

(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 :    o       No :   ý

(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 :    o       No :   ý

(Indicate by check mark whether the registrant 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 :    o       No :   ý

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

NOTICE TO THE MARKET

Oi S.A. – In Judicial Reorganization (“Company”), in continuity and in addition to the information contained in the Notices to the Market disclosed by the Company on December 19, 2016, January 30, 2017, March 2, 2017 and March 31, 2017, informs its shareholders and the market in general that Orascom TMT Investments S.à.r.l. voluntarily sent a letter to the Company on this date extending the validity of its suggestions for an alternative judicial reorganization plan until June 1, 2017.

The Company will keep its shareholders and the market informed of the development of the subject matter of this Notice to the Market.

Rio de Janeiro, May 2, 2017.

Ricardo Malavazi Martins

Chief Financial and Investor Relations Officer

Oi S.A. – In Judicial Reorganization