EX-4.3



 Exhibit 4.3 

SUPPLEMENTAL INDENTURE 

SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”) dated as of November 1, 2016, among the entities listed in Annex
A (the “New Guarantors”), subsidiaries of ALCOA CORPORATION (formerly known as Alcoa Upstream Corporation), a corporation organized under the laws of Delaware (the “Company”), the Company, ALCOA NEDERLAND HOLDING
B.V. (the “Issuer”) and THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., as the Trustee, (the “Trustee”) under the indenture referred to below. 

W I T N E S S E T H : 
 WHEREAS
the Issuer and the Company have heretofore executed and delivered to the Trustee an Indenture (the “Indenture”) dated as of September 27, 2016, providing for the issuance of 6.75% Senior Unsecured Notes due 2024 and 7.00%
Senior Unsecured Notes due 2026 (collectively, the “Notes”); 
 WHEREAS the Indenture provides that under certain
circumstances the Company and the Issuer are required to cause the New Guarantors to execute and deliver to the Trustee a supplemental indenture pursuant to which the New Guarantors shall unconditionally guarantee all the Issuer’s obligations
under the Notes pursuant to Subsidiary Guarantees on the terms and conditions set forth herein and under the Indenture; and 
 WHEREAS
pursuant to Section 9.1 of the Indenture, the Trustee, the Issuer, the Company and the New Guarantors are authorized to execute and deliver this Supplemental Indenture; 

NOW THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged,
the New Guarantors, the Issuer, the Company and the Trustee mutually covenant and agree for the equal and ratable benefit of the Holders of the Notes as follows: 

1. Capitalized Terms. Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture. 

2. Agreement to Guarantee. The New Guarantors hereby agree, jointly and severally with all the existing Guarantors, to unconditionally
guarantee the Issuer’s obligations under the Notes on the terms and subject to the conditions set forth in Article 10 of the Indenture and to be bound by all other applicable provisions of the Indenture and the Notes. 

3. Limitation on obligations of Norwegian Guarantors. The obligations and liabilities of each New Guarantor incorporated in Norway in
its capacity as New Guarantor (each a “Norwegian Guarantor”) under the Indenture, this Supplemental Indenture and the Notes shall be limited by such mandatory provisions of law applicable to such Norwegian Guarantor limiting the
legal capacity or ability of such Norwegian Guarantor to grant and/or honour a guarantee thereunder (including, but not limited to, the provisions of Sections 8-7 to 8-10 (both inclusive) of the Norwegian Private Limited Liability Companies Act of
13 June 1997 No. 44, regulating unlawful financial assistance and other prohibited loans, guarantees and joint and several liability as well as providing of security), and the obligations and liability of each Norwegian Guarantor under
Article 10 of the Indenture or under any other guarantee or indemnity contained in this Supplemental Indenture and the Notes shall only apply to the extent not so limited. Under no circumstances shall the obligations and liabilities of any Norwegian
Guarantor cover the debt and/or other liabilities incurred in respect of the purchase of the shares in a Norwegian Guarantor or the shares in any of such Norwegian Guarantor’s holding companies. 







 4. Ratification of Indenture; Supplemental Indentures Part of Indenture. Except as
expressly amended hereby, the Indenture is in all respects ratified and confirmed and all the terms, conditions and provisions thereof shall remain in full force and effect. This Supplemental Indenture shall form a part of the Indenture for all
purposes, and every Holder of Notes heretofore or hereafter authenticated and delivered shall be bound hereby. 
 5. Governing Law.
THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK. 
 6. Waiver of
Jury Trial. EACH OF THE NEW GUARANTORS AND THE TRUSTEE HEREBY IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS SUPPLEMENTAL
INDENTURE, THE INDENTURE, THE NOTES, THE SUBSIDIARY GUARANTEES OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY. 
 7. Trustee Makes No
Representation. The Trustee makes no representation as to the validity or sufficiency of this Supplemental Indenture. 
 8.
Counterparts. The parties may sign any number of copies of this Supplemental Indenture. Each signed copy shall be an original, but all of them together represent the same agreement. The exchange of copies of this Supplemental Indenture and of
signature pages by facsimile or .pdf transmission shall constitute effective execution and delivery of this Supplemental Indenture as to the parties hereto and may be used in lieu of the original Indenture for all purposes. Signatures of the parties
hereto transmitted by facsimile or .pdf shall be deemed to be their original signatures for all purposes. 
 9. Effect of Headings.
The Section headings herein are for convenience only and shall not affect the construction thereof. 
 [Signature Page Follows]








 IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly
executed as of the date first above written. 
  

					
	ALCOA NEDERLAND HOLDING B.V.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name:	 	Renato C.A. Bacchi
		 	Title:	 	Managing Director
	
	ALCOA CORPORATION
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name:	 	Renato C.A. Bacchi
		 	Title:	 	Treasurer
	
	THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.
		
	By	 	 /s/ Teresa Petta

		 	Name:	 	Teresa Petta
		 	Title:	 	Vice President
	
	ALCOA ALLOWANCE MANAGEMENT, INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name:	 	Renato C.A. Bacchi
		 	Title:	 	Treasurer
	
	ALCOA ALUMINIO S.A.
		
	By	 	 /s/ Otávio Augusto Rezende Carvalheira

		 	Name:	 	Otávio Augusto Rezende Carvalheira
		 	Title:	 	Chief Executive Officer
	
	ALCOA ASIA LIMITED
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name:	 	Renato C.A. Bacchi
		 	Title:	 	Vice President and Treasurer



  
 [Signature Page to
Supplemental Indenture] 









			
	ALCOA BUSINESS PARK LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	ALCOA CANADA CO.
		
	By	 	 /s/ Jean-Francois Cyr

		 	Name: Jean-Francois Cyr
		 	Title:   Vice President
	
	ALCOA CANADA HOLDING CO.
		
	By	 	 /s/ Jean-Francois Cyr

		 	Name: Jean-Francois Cyr
		 	Title:   Vice President
	
	ALCOA DIMARC INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	ALCOA DO BRASIL INDUSTRIA E COMERCIO LTDA.
		
	By	 	 /s/ Otávio Augusto Rezende Carvalheira

		 	Name: Otávio Augusto Rezende Carvalheira
		 	Title:   Chief Executive Officer



  
 [Signature Page to
Supplemental Indenture] 









			
	ALCOA ENERGY SERVICES, INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Treasurer
	
	ALCOA EUROPEAN FINANCING LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	ALCOA FUELS, INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Treasurer
	
	ALCOA HOLLAND B.V.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Managing Director
	
	ALCOA IK SERVICES INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer



  
 [Signature Page to
Supplemental Indenture] 









			
	ALCOA MATERIALS MANAGEMENT, INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	ALCOA NORWAY ANS
		
	By	 	 /s/ Kai Rune Heggland

		 	Name: Kai Rune Heggland
		 	Title:   Chief Executive Officer
	
	ALCOA RECYCLING COMPANY, INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	ALCOA REMEDIATION MANAGEMENT LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	ALCOA SOUTH CAROLINA, INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer



  
 [Signature Page to
Supplemental Indenture] 









			
	ALCOA TECHNICAL CENTER LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	ALCOA TREASURY S.Á R.L
		
	By	 	 /s/ Gerard Stassen

		 	Name: Gerard Stassen
		 	Title:   Manager
	
	ALCOA USA CORP.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	ALCOA USA HOLDING COMPANY
		
	By	 	 /s/ Maria J. Young

		 	Name: Maria J. Young
		 	Title:   President and Treasurer
	
	ALCOA WARRICK LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer



  
 [Signature Page to
Supplemental Indenture] 









					
	ALCOA WARRICK M&E, G.P.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Partner:	 	Alcoa DiMarc, Inc.
		 	Signatory:	 	Renato C.A. Bacchi
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Partner:	 	Reynolds Metals Company, LLC
		 	Signatory:	 	Renato C.A. Bacchi
	
	ALCOA WENATCHEE LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name:	 	Renato C.A. Bacchi
		 	Title:	 	Vice President and Treasurer
	
	ALCOA-ALUMINERIE DE DESCHAMBAULT L.P. by its general partner, ALCOA-LAURALCO MANAGEMENT COMPANY
		
	By	 	 /s/ Jean-Francois Cyr

		 	Name:	 	Jean-Francois Cyr
		 	Title:	 	Vice President
	
	ALCOA-LAURALCO MANAGEMENT COMPANY
		
	By	 	 /s/ Jean-Francois Cyr

		 	Name:	 	Jean-Francois Cyr
		 	Title:	 	Vice President



  
 [Signature Page to
Supplemental Indenture] 









			
	ALUMINERIE LAURALCO S.Á R.L
		
	By	 	 /s/ Gerard Stassen

		 	Name: Gerard Stassen
		 	Title:   Manager
	
	BADIN BUSINESS PARK LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	COMPANHIA GERAL DE MINAS
		
	By	 	 /s/ Otávio Augusto Rezende Carvalheira

		 	Name: Otávio Augusto Rezende Carvalheira
		 	Title:   Chief Executive Officer
	
	EASTALCO ALUMINUM COMPANY
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	INTALCO ALUMINUM LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer



  
 [Signature Page to
Supplemental Indenture] 









			
	LAMAR QUEBEC COMPANY
		
	By	 	 /s/ Jean-Francois Cyr

		 	Name: Jean-Francois Cyr
		 	Title:   Vice President
	
	LUXCOA S.Á R.L
		
	By	 	 /s/ Gerard Stassen

		 	Name: Gerard Stassen
		 	Title:   Manager
	
	NORSK ALCOA AS
		
	By	 	 /s/ Henrik Tveten

		 	Name: Henrik Tveten
		 	Title:   Chief Executive Officer
	
	NORSK ALCOA HOLDING AS
		
	By	 	 /s/ Henrik Tveten

		 	Name: Henrik Tveten
		 	Title:   Chief Executive Officer
	
	NORTHWEST ALLOYS, INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer



  
 [Signature Page to
Supplemental Indenture] 









			
	PRESIDENTIAL DEVELOPMENT CORPORATION
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	RB SALES COMPANY, LIMITED
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	REYNOLDS METALS COMPANY LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	REYNOLDS METALS DEVELOPMENT COMPANY
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	REYNOLDS METALS EXPLORATION, INC.
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer



  
 [Signature Page to
Supplemental Indenture] 









			
	RMC DELAWARE, LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer
	
	RMC PROPERTIES LLC
		
	By	 	 /s/ Renato C.A. Bacchi

		 	Name: Renato C.A. Bacchi
		 	Title:   Vice President and Treasurer



  
 [Signature Page to
Supplemental Indenture] 








 Annex A 

New Guarantors 
 Alcoa Allowance
Management, Inc. 
 Alcoa Aluminio S.A. 
 Alcoa Asia Limited

 Alcoa Business Park LLC 
 Alcoa Canada Co. 

Alcoa Canada Holding Co. 
 Alcoa DiMarc Inc. 

Alcoa do Brasil Industria e Comercio Ltda. 
 Alcoa Energy
Services, Inc. 
 Alcoa European Financing LLC 
 Alcoa Fuels,
Inc. 
 Alcoa Holland B.V. 
 Alcoa IK Services Inc. 

Alcoa Materials Management, Inc. 
 Alcoa Norway ANS 

Alcoa Recycling Company, Inc. 
 Alcoa Remediation Management LLC

 Alcoa South Carolina, Inc. 
 Alcoa Technical Center LLC 

Alcoa Treasury S.à r.l 
 Alcoa USA Corp. 

Alcoa USA Holding Company 
 Alcoa Warrick LLC 

Alcoa Warrick M&E, G.P. 
 Alcoa Wenatchee LLC 

Alcoa-Aluminerie de Deschambault L.P. 
 Alcoa-Lauralco Management
Company 
 Aluminerie Lauralco S.à r.l 
 Badin Business
Park LLC 
 Companhia Geral de Minas 
 Eastalco Aluminum Company

 Intalco Aluminum LLC 
 Laqmar Quebec Company 

Luxcoa S.à r.l 
 Norsk Alcoa AS 

Norsk Alcoa Holding AS 
 Northwest Alloys, Inc. 

Presidential Development Corporation 
 RB Sales Company, Limited
Reynolds 
 Metals Company LLC Reynolds Metals 
 Development
Company 
 Reynolds Metals Exploration, Inc. 
 RMC Delaware, LLC

 RMC Properties LLC