Form 6-K Fibria Celulose S.A. For: Oct 31

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 of

the Securities Exchange Act of 1934

Dated October 31, 2016

Commission File Number: 1-15018

Fibria Celulose S.A.

Fidêncio Ramos, 302 — 3rd and (part of) 4th floors

Edifício Vila Olímpia, Torre B, Bairro Vila Olímpia

04551-010, São Paulo, SP, 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:  x             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:  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:  o             No:  x

(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:  x

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

Fibria Celulose S.A.

Unaudited consolidated interim financial information at September 30, 2016

and Report on Review of Interim

Financial Information

REPORT ON REVIEW OF CONSOLIDATED INTERIM FINANCIAL INFORMATION

To the Board of Directors and Shareholders

Fibria Celulose S.A

São Paulo — SP

Introduction

We have reviewed the accompanying consolidated interim accounting information of Fibria Celulose S.A., for the quarter ended September 30, 2016, comprising the balance sheet at that date, the statements of income and comprehensive income for the quarter and nine-month period then ended, the statements of changes in equity and cash flows for the nine-month period then ended, and a summary of significant accounting policies and other explanatory information.

Management is responsible for the preparation of the consolidated interim accounting information in accordance with the Deliberation CVM 673/11 (which approved accounting standard CPC 21(R1) - Interim Financial Reporting), and International Accounting Standard (IAS) 34 - Interim Financial Reporting issued by the International Accounting Standards Board (IASB).   Our responsibility is to express a conclusion on this interim accounting information based on our review.

Scope of the review

We conducted our review in accordance with Brazilian and International Standards on Reviews of Interim Financial Information (Brazilian audit standard NBC TR 2410, wholly converged to ISRE 2410 — Review of Interim Financial Information Performed by the Independent Auditor of the Entity, respectively).   A review of interim information consists of making inquiries, primarily of persons responsible for financial and accounting matters, and applying analytical and other review procedures.   A review is substantially less in scope than an audit conducted in accordance with Brazilian and International Standards on Auditing and consequently does not enable us to obtain assurance that we would become aware of all significant matters that might be identified in an audit.   Accordingly, we do not express an audit opinion.

Conclusion on the consolidated interim information

Based on our review, nothing has come to our attention that causes us to believe that the accompanying consolidated interim accounting information referred to above has not been prepared, in all material respects, in accordance with Deliberation CVM 673/11 and IAS 34.

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Prior year and period corresponding balances

The amounts corresponding to the financial statements for the year ended December 31, 2015, and to the interim accounting information for the quarter ended on September 30, 2015, presented for comparison purposes, were audited by other auditors who issued reports dated January 27, 2016 and October 22, 2015, respectively, without qualification.

São Paulo, October 25, 2016.

BDO RCS Auditores Independentes SS

CRC 2SP 013846/O-1

Eduardo Affonso de Vasconcelos

Accountant — CRC-1SP166001/O-3

Francisco de Paula dos Reis Júnior

Accountant CRC 1 SP 139268/O-6

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Fibria Celulose S.A.

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Fibria Celulose S.A.

The accompanying notes are an integral part of these unaudited consolidated interim financial information.

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Fibria Celulose S.A.

Unaudited consolidated interim statement of profit or loss

In thousands of Reais, except for the earnings per share

The accompanying notes are an integral part of these unaudited consolidated interim financial information.

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Fibria Celulose S.A.

Unaudited consolidated interim statement of comprehensive income

In thousands of Reais

The accompanying notes are an integral part of these unaudited consolidated interim financial information.

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Fibria Celulose S.A.

Unaudited interim statement of changes in shareholders’ equity

In thousands of Reais

The accompanying notes are an integral part of these consolidated interim financial information.

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Fibria Celulose S.A.

Unaudited consolidated interim statement of cash flows

In thousands of Reais

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The accompanying notes are an integral part of these unaudited consolidated interim financial information.

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Fibria Celulose S.A.

Notes to the unaudited consolidated interim financial information at September 30, 2016

In thousands of Reais, unless otherwise indicated

1                                        Operations and current developments

(a)                                General information

Fibria Celulose S.A. is incorporated under the laws of the Federal Republic of Brazil, as a publicly-held company. Fibria Celulose S.A. and its subsidiaries are referred to in this consolidated interim financial information as the “Company”, “Fibria”, or “we”. We have the legal status of a share corporation, operating under Brazilian corporate law. Our headquarter and principal executive officers are located in São Paulo, SP, Brazil.

We are listed on the stock exchange of São Paulo (BM&FBOVESPA) and the New York Stock Exchange (NYSE) and we are subject to the reporting requirements of the Brazilian Comissão de Valores Mobiliários (CVM) and the United States Securities and Exchange Commission (SEC).

Our activities are focused on the growth of renewable and sustainable forests and the manufacture and sale of bleached eucalyptus kraft pulp. Forests in formation are located in the States of São Paulo, Mato Grosso do Sul, Minas Gerais, Rio de Janeiro, Espírito Santo, Bahia and Rio Grande do Sul.

We operate in a single operating segment, which is the producing and selling of short fiber pulp, with our pulp production facilities located in the cities of Aracruz (State of Espírito Santo), Três Lagoas (State of Mato Grosso do Sul), Jacareí (State of São Paulo) and Eunápolis (State of Bahia) (Veracel Celulose S.A. (“Veracel”), a jointly- controlled entity).

The pulp produced for export is delivered to customers by sea vessels on the basis of long-term contracts with the owners of these vessels, through the ports of Santos, located in the State of São Paulo (operated under a concession from Federal Government until 2017) and Barra do Riacho, located in the State of Espírito Santo (operated by our subsidiary Portocel - Terminal Especializado Barra do Riacho S.A.).

On December 9, 2015, we participated in the public auction nº 03/2015, promoted by “Agência Nacional de Transportes Aquaviários - ANTAQ”, a regulatory agency, for the leasing of the public areas and infrastructures for handling and storage of paper, pulp and general cargo, for 25 years (renewable for 25 years). The Company was awarded the contract based on its proposal for the Macuco Terminal (STS07), located in the port of Santos, State of São Paulo, in the amount of R$ 115,047, which the approval of the public auction and the adjudication were published in the Federal Official Gazette on March 2, 2016. On September 29, 2016, we signed the instrument of investiture of the terminal.

With the approval of the result and based on the standards ICPC 01 (R1) / IFRIC 12 - Service Concession Arrangements and OCPC 05 - Concession Contracts, the subsidiary Fibria Terminal de Celulose de Santos SPE S.A., recently established by the Company for the administration of Macuco Terminal, recognized on March 2016, the amount of R$ 115,047 related to the grant concession rights into the group of “Intangible assets”, which will be amortized over the concession period.

The main investments according to the contract include:

(i)                 a new storage facility, handling and transshipment of cargo equipment, with static capacity of 75,000 tons at least, ensuring the movement of 1,800,000 tons of pulp bales per year; and,

(ii)              the implementation of new railway lines for access to port facilities.

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Fibria Celulose S.A.

Notes to the unaudited consolidated interim financial information at September 30, 2016

In thousands of Reais, unless otherwise indicated

The startup of the terminal is expected for the second semester of 2017.

In May 2016, we started the acquisition of hardwood pulp produced by Klabin S.A. (“Klabin”), at its plant located in the city of Ortigueira, in the state of Paraná, as supply agreement signed between the parties and subject of disclosure to the market on May 4, 2015.

The agreement term is six years from the beginning of the plant operations (which may be extended upon agreement between the parties), being four years at a minimum volume of 900,000 tons of short fiber pulp (except if otherwise agreed between the parties) and two years of a gradual reduction of volume (phase out), equivalents to, respectively, 75% and 50% of the volume delivered in the fourth year of the agreement. The purchase price of the volume from Klabin will be based on the average net price charged by the Company and the volume acquired might be sold for countries outside South America.

(b)                                Non-current assets held for sale Losango project assets

On December 28, 2012, the Company and CMPC Celulose Riograndense Ltda. (“CMPC”) signed the definitive Purchase and Sale Agreement for the sale of all of the Losango project assets, comprising approximately 100 thousand hectares of land owned by Fibria and approximately 39 thousand hectares of planted eucalyptus and leased land, all located in the State of Rio Grande do Sul, in the amount of R$615 million.

The amount of R$ 477 million was received in advance the amount of R$ 477 million, recognized under “Liabilities related to the assets held for sale”. Another installment, amounting to R$ 140 million, was deposited in an escrow account and will be released to us once additional government approvals are obtained. In case of the approvals is not obtained after the period of 96 months, will be returned to CMPC the amount paid to us, plus interest and the escrow deposits made by CMPC will revert.

Since the signing of agreement with CMPC, we have taken action to obtain the approvals needed, such as the fulfillment of all conditions precedent, the partial renewal of the area operating license and filing the documentation required by the government agencies. Management’s best estimate is that approval will be granted.

We have concluded that these assets should remain classified as “assets held for sale” as non-current assets as at September 30, 2016. However, the completion of the sale is not under our sole control and depends on various government approvals, which have been slower than expected.

The Losango assets did not generate any significant impact in the nine-month period ended September 30, 2016 and 2015, since that at this moment, the result of the transaction has not been recognized.

(c)                                 Expansion plan of the Três Lagoas Unit

On May 14, 2015, the Board of Directors approved the Horizonte 2 Project for the construction of the second Três Lagoas pulp production line.

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Fibria Celulose S.A.

Notes to the unaudited consolidated interim financial information at September 30, 2016

In thousands of Reais, unless otherwise indicated

The construction of Horizonte 2 Project has already started and consists of a new bleached eucalyptus pulp production line with a capacity of 1.95 million tons per year and an estimated investment of US$2.3 billion. The startup of the line is projected for the fourth quarter of 2017 and the physical execution is approximately 60% concluded.

The Project is being financed from the Company’s operating cash flows and financing agreements negotiated with financial institutions.

2                                        Presentation of consolidated interim financial information and summary of significant accounting policies

2.1                              Consolidated interim financial information - basis of preparation

The consolidated interim financial information have been prepared under the historical cost convention, as modified by available-for-sale financial assets, other assets and financial liabilities (including derivative instruments) measured at fair value.

(a)                                Accounting policies adopted

The consolidated interim financial information have been prepared and is being presented in accordance with IAS 34 and Deliberation 673/11 issued by the Brazilian Securities and Exchange Commission (CVM), which approved the CPC 21(R1) - “Interim Financial Reporting” as issued by the International Accounting Standards Board (IASB) and the Accounting Statements Committee Standards (CPC), and disclose all (and only) the applicable significant information related to the financial statements, which is consistent with the information utilized by management in the performance of its duties.

The consolidated interim financial information should be read in conjunction with the audited financial statements for the year ended December 31, 2015, considering that its purpose is to provide an update on the activities, events and significant circumstances in relation to those presented in the annual financial statements.

The current accounting practices, which include the measurement principles for the recognition and valuation of the assets and liabilities, the calculation methods used in the preparation of this consolidated interim financial information and the estimates used, are the same as those used in the preparation of the most recent annual financial statements, except for the item 2.2.1 below and items related to the adoption of the new standards, amendments and interpretations issued by IASB and CVM, as detailed in Note 3 below.

(b)                                Approval of the consolidated interim financial information

The unaudited consolidated interim financial information were approved by the Board of Directors on October 25, 2016.

2.2                              Critical accounting estimates and assumptions

Estimates and assumptions are continually evaluated and are based on historical experience and other factors, including expectations of future events that are believed to be reasonable under the

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Fibria Celulose S.A.

Notes to the unaudited consolidated interim financial information at September 30, 2016

In thousands of Reais, unless otherwise indicated

circumstances. Accounting estimates will, by definition, seldom match the actual results. In the nine-month period ended September 30, 2016, except for the item 2.2.1 below, there were no significant changes in the critical estimates and assumptions which are likely to result in significant adjustments to the carrying amounts of assets and liabilities during the current period, compared to those disclosed in Note 3 to our most recent annual financial statements.

2.2.1                    Changing on critical accounting estimates and assumptions

(a)                                Biological assets

The Company reviewed the assumptions used in the calculating of the fair value of biological assets and concluded as appropriate changing, from 2016, the assumption called “actual planted area”, so that the immature forests (up to two years from the date of planting) are maintained at historical cost, as a result of the Management’s understanding that during this period, the historical cost of biological assets approximates of their fair value. The purpose of this change is reflect the experience acquired in the measurement process of biological assets and the alignment of the calculation methodology to the Company’s forest management, which considers continuous forest inventories with the purpose of estimate the volume of timber stock or future production projections, represented by the average annual growth (“IMA”), from the third year of planting.

The assumption regarding the “net average sale price” of biological assets (measured in R$/m³) is now supported only in market prices research, in order to maximize the usage of external and independent data to measure the fair value of the forests.

If the aforementioned changes would not have been made, the fair value adjustment of biological assets would have generated a lower expense of R$ 30,471 in relation to the amount recognized in the nine-month period ended September 30, 2016.

The other assumptions used by the Company to calculate the fair value of biological assets have not changed. See details about the biological assets in Note 16.

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Fibria Celulose S.A.

Notes to the unaudited consolidated interim financial information at September 30, 2016

In thousands of Reais, unless otherwise indicated

3                                        New standards, amendments and interpretations issued by IASB and CVM

The standards below have been issued and are effectives for future periods, as from January 1, 2018. We have not early adopted these standards.