ENERSIS S.A. ( ENERSIS )

20−F Annual and transition report of foreign private issuers pursuant to sections 13 or 15(d) Filed on 5/31/2011 Filed Period 12/31/2010 Table of Contents SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 20−F o REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR 12(g) OF THE SECURITIES EXCHANGE ACT OF 1934 OR ⌧ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2010 OR o TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 OR o SHELL COMPANY REPORT PURSUANT TO SECTION 23 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Date of event requiring this shell company report

For the transition period from to

Commission file number: 001−12440

ENERSIS S.A. (Exact name of Registrant as specified in its charter)

ENERSIS S.A. (Translation of Registrant’s name into English)

CHILE (Jurisdiction of incorporation or organization)

SANTA ROSA 76, SANTIAGO, CHILE (Address of principal executive offices)

Nicolás Billikopf, phone: (56−2) 353−4639, fax: (56−2) 378−4789, [email protected], Santa Rosa 76, Piso 15, Santiago, Chile (Name, Telephone, E−mail and/or Facsimile number and Address of Company Contact Person)

Securities registered or to be registered pursuant to Section 12(b) of the Act:

Title of Each Class Name of Each Exchange on Which Registered American Depositary Shares representing Common Stock New York Stock Exchange Common Stock, no par value * New York Stock Exchange $ 249,734,000 7.40% Notes due December 1, 2016 New York Stock Exchange $ 858,000 6.60% Notes due December 1, 2026 New York Stock Exchange

*Listed, not for trading, but only in connection with the registration of American Depositary Shares, pursuant to the requirements of the Securities and Exchange Commission.

Securities registered or to be registered pursuant to Section 12(g) of the Act: None Table of Contents

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act:

$ 350,000,000 7.375% Notes due January 15, 2014

Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report:

Shares of Common Stock: 32,651,166,465

Indicate by check mark if the registrant is a well−known seasoned issuer, as defined in Rule 405 of the Securities Act: ⌧ Yes o No

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934: o Yes ⌧ No

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days: ⌧ Yes o No

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S−T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). o Yes o No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non−accelerated filer. See definition of “accelerated filer and large accelerated filer” in Rule 12b−2 of the Exchange Act:

Large accelerated filer ⌧ Accelerated filer o Non−accelerated filer o

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

U.S. GAAP o International Financial Reporting Standards as issued Other o by the International Accounting Standards Board ⌧

Indicate by check mark which financial statement item the registrant has elected to follow: o Item 17 ⌧ Item 18

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b−2 of the Exchange Act): o Yes ⌧ No Table of Contents

“Enersis’ Simplified Organizational Structure” (*) (*) Only principal operating subsidiaries are presented here. The percentages listed for each of our subsidiaries represents Enersis’economic interest in such subsidiary.

2 Table of Contents

TABLE OF CONTENTS

Page

GLOSSARY 4 INTRODUCTION 9 Financial Information 9 Technical Terms 10 Calculation of Economic Interest 10 Forward−Looking Statements 10 PART I 12 Item 1. Identity of Directors, Senior Management and Advisers 12 Item 2. Offer Statistics and Expected Timetable 12 Item 3. Key Information 12 Item 4. Information on the Company 23 Item 4A. Unresolved Staff Comments 84 Item 5. Operating and Financial Review and Prospects 85 Item 6. Directors, Senior Management and Employees 115 Item 7. Major Shareholders and Related Party Transactions 126 Item 8. Financial Information 127 Item 9. The Offer and Listing 129 Item 10. Additional Information 131 Item 11. Quantitative and Qualitative Disclosures about Market Risk 145 Item 12 Description of Securities Other Than Equity Securities 149 PART II 150 Item 13. Defaults, Dividend Arrearages and Delinquencies 150 Item 14. Material Modifications to the Rights of Security Holders and Use of Proceeds 150 Item 15. Controls and Procedures 150 Item 16A. Audit Committee Financial Expert 151 Item 16B. Code of Ethics 151 Item 16C. Principal Accountant Fees and Services 152 Item 16D. Exemptions from Listing Requirements for Audit Committees 153 Item 16E. Purchases of Equity Securities by the Issuer and Affiliated Purchasers 153 Item 16F. Change in Registrant's Certifying Accountants 153 Item 16G. Corporate Governance 154 PART III 155 Item 17. Financial Statements 155 Item 18. Financial Statements 155 Item 19. Exhibits 155

3 Table of Contents

GLOSSARY

Acciona ACCIONA, S.A. Spanish construction holding company. Together with Enel, Acciona held a controlling interest in Endesa Spain until June 25, 2009.

AFP Administradora de Fondos de Pensiones A legal entity that manages a Chilean pension fund.

Ampla Ampla Energia e Serviços S.A. Brazilian distribution company operating in Rio de Janeiro, owned by Endesa Brasil, a subsidiary of Enersis.

ANEEL Agéncia Nacional de Energia Elétrica Brazilian governmental agency for electric energy.

Betania Central Hidroeléctrica de Betania S.A. E.S.P. Endesa Chile’s Colombian subsidiary which merged with Emgesa, another Endesa Chile subsidiary, in 2007.

Cachoeira Dourada Centrais Elétricas Cachoeira Dourada S.A. Brazilian generation company owned by Endesa Brasil, a subsidiary of Enersis.

CAM Compañía Americana de Multiservicios Ltda. Enersis’ subsidiary engaged in the electrical parts procurement business.

CAMMESA Compañía Administradora del Mercado Mayorista Argentine autonomous entity in charge of the operation of the Eléctrico S.A. Mercado Eléctrico Mayorista (Wholesale Electricity Market), or MEM. CAMMESA’s stockholders are generation, transmission and distribution companies, large users and the Secretariat of Energy.

CDEC Centro de Despacho Económico de Carga Autonomous entity in two Chilean electric systems in charge of coordinating the efficient operation and dispatch of generation units to satisfy demand.

Celta Compañía Eléctrica Tarapacá S.A. Endesa Chile’s subsidiary that operates in the SING with thermal plants.

Cemsa Endesa Cemsa S.A. Energy trading company with operations in Argentina, a subsidiary of Endesa Chile.

Chilectra Chilectra S.A. Chilean electricity distribution company operating in the Santiago metropolitan area, a subsidiary of Enersis.

CIEN Companhia de Interconexão Energética S.A. Brazilian transmission company, wholly−owned by Endesa Brasil, a subsidiary of Enersis.

CNE Comisión Nacional de Energía Chilean National Energy Commission, governmental entity with responsibilities under the Chilean regulatory framework.

4 Table of Contents

Codensa Codensa S.A. E.S.P. Colombian distribution company that operates mainly in Bogotá, and is a subsidiary of Enersis.

Coelce Companhia Energética do Ceará S.A. Brazilian distribution company operating in the state of Ceará. Coelce is controlled by Endesa Brasil, a subsidiary of Enersis.

CREG Comisión de Regulación de Energía y Gas Colombian Commission for the Regulation of Energy and Gas.

CTM Compañía de Transmisión del Mercosur S.A Endesa Brasil’s subsidiary transmission company with operations in Argentina.

DECA Distribuidora Eléctrica de Cundinamarca S.A. Colombian distribution company, subsidiary of Codensa.

Edegel Edegel S.A.A. Peruvian generation company, subsidiary of Endesa Chile.

Edelnor Empresa de Distribución Eléctrica de Lima Norte S.A.A. Peruvian distribution company with a concession area in the northern part of Lima, and a subsidiary of Enersis.

Edesur Empresa Distribuidora Sur S.A. Argentine distribution company with concession area in the south of the Buenos Aires greater metropolitan area, and a subsidiary of Enersis.

EEB Empresa de Energía de Bogota S.A. Colombian stated−owned financial and energy holding company, with investments in the electricity generation, transmission, commercialization and distribution sectors; and in the natural gas transmission, distribution and commercialization sectors.

EEC Empresa de Energía de Cundinamarca S.A. Colombian electricity distribution company, subsidiary of DECA.

El Chocón Hidroeléctrica El Chocón S.A. Endesa Chile’s Argentine generation subsidiary with two hydroelectric plants, El Chocón and Arroyito, both located in the Limay River, Argentina.

Elesur Elesur S.A. A former Chilean subsidiary of Enersis that absorbed Chilectra, and later changed its name to Chilectra.

Emgesa Emgesa S.A. E.S.P. Colombian generation company controlled by Endesa Chile.

Endesa Brasil Endesa Brasil S.A. Brazilian holding company, a subsidiary of Enersis.

5 Table of Contents

Endesa Chile Empresa Nacional de Electricidad S.A. Our generation subsidiary with consolidated operations in four countries in South America.

Endesa Costanera Endesa Costanera S.A. Argentine generation company controlled by Endesa Chile.

Endesa Eco Endesa Eco S.A. Chilean electricity company, owner of Central Eólica Canela S.A. and Ojos de Agua mini hydro plant. Endesa Eco is an Endesa Chile subsidiary.

Endesa Fortaleza Central Geradora Termelétrica Fortaleza S.A. Operates a combined cycle generating plant, located in the state of Ceará. Endesa Fortaleza is wholly−owned by our subsidiary Endesa Brasil.

Endesa Latinoamérica Endesa Latinoamérica, S.A. A subsidiary of Endesa Spain and our direct controller, formerly known as Endesa Internacional, S.A.U.

Endesa Spain ENDESA, S.A. A Spanish electricity generation and distribution company with a 60.6% beneficial interest in Enersis.

Enel Enel S.p.A. Italian power company, with a 92.1% controlling ownership of Endesa Spain.

Enersis ENERSIS S.A. Our company, a publicly held limited liability stock company incorporated under the laws of the Republic of Chile, with subsidiaries engaged primarily in the generation, transmission and distribution of electricity in Chile, Argentina, Brazil, Colombia and Peru. Registrant of this report.

ENRE Ente Nacional Regulatorio de la Energía Argentine national regulatory authority for the energy sector.

Etevensa Empresa de Generación Termoeléctrica Ventanilla S.A. Peruvian generation company that merged with Edegel in 2006.

FONINVEMEM Fondo Para Inversiones Necesarias Que Permitan Argentine fund created to increase electricity supply in the MEM. Incrementar La Oferta De Energía Eléctrica En El Mercado Eléctrico Mayorist