Second Supplemental Indenture



 Exhibit 4.3 
 AMERICAN TOWER CORPORATION 
 and 

THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A. 
 as Trustee 
  

 
 SECOND
SUPPLEMENTAL INDENTURE 
 Dated as of December 30, 2011 

to 
 INDENTURE

 Dated as of October 1, 2007 







 TABLE OF CONTENTS 

 

							
	 	  	 	  	Page	 
	Article I Assumption	  	 	1	  
	 Section 1.01.
	  	Assumption of Obligations	  	 	1	  
	 Section 1.02.
	  	Successor Corporation Substituted	  	 	2	  
		
	 Article II Miscellaneous
	  			
	 Section 2.01.
	  	Trust Indenture Act Controls	  	 	2	  
	 Section 2.02.
	  	Counterpart Originals	  	 	2	  
	 Section 2.03.
	  	Governing Law	  	 	2	  
	 Section 2.04.
	  	No Adverse Interpretation of Other Agreements	  	 	2	  
	 Section 2.05.
	  	Severability	  	 	2	  
	 Section 2.06.
	  	Headings	  	 	2	  
	 Section 2.07.
	  	No Personal Liability of Directors, Officers, Employees and Stockholders	  	 	2	  
	 Section 2.08.
	  	Provisions of Supplemental Indenture for the Sole Benefit of Parties and Holders	  	 	3	  
	 Section 2.09.
	  	Execution as Supplemental Indenture	  	 	3	  
	 Section 2.10.
	  	Ratification and Incorporation of Indenture	  	 	3	  
	 Section 2.11.
	  	Trustee	  	 	3	  


  
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 SECOND SUPPLEMENTAL INDENTURE (the “Supplemental Indenture”), dated
as of December 30, 2011, by and among American Tower Corporation, a Delaware corporation (“American Tower”), American Tower REIT, Inc., a Delaware corporation and wholly owned subsidiary of American Tower (“American
Tower REIT”), and The Bank of New York Mellon Trust Company, N.A., a national banking association, as trustee (the “Trustee”). Capitalized terms used herein without definition shall have the respective meanings ascribed to
them in the Indenture (as defined below). 
 WITNESSETH THAT: 

WHEREAS, American Tower and the Trustee are parties to an indenture, dated as of October 1, 2007, as supplemented by a supplemental
indenture dated as of December 2, 2008 (as so supplemented, amended or otherwise modified from time to time, the “Indenture”), with respect to American Tower’s 7.000% Senior Notes due 2017 (the “Notes”);

 WHEREAS, American Tower and American Tower REIT entered into an Agreement and Plan of Merger dated as of August 24, 2011
(the “Merger Agreement”), providing for the merger of American Tower with and into American Tower REIT (the “Merger”), with American Tower REIT as the surviving corporation; 

WHEREAS, Section 5.01(1) of the Indenture provides that in the event of a merger, the surviving corporation shall expressly assume
by supplemental indenture all of American Tower’s obligations under the Indenture and the Notes; 
 WHEREAS, the Merger
complies with the other provisions of Section 5.01 of the Indenture; 
 WHEREAS, Section 9.01(2) of the Indenture
permits American Tower and the Trustee to enter into a supplemental indenture to the Indenture without prior notice to or consent of the Holders of any outstanding Notes for the purpose of evidencing the assumption of American Tower’s
obligations to Holders of the Notes in the case of a merger, amalgamation or consolidation of American Tower or sale of all or substantially all of the assets of American Tower; 

WHEREAS, effective as of 11:59 pm on December 31, 2011 (the “Effective Time”), American Tower will merge pursuant
to the Merger Agreement, with American Tower REIT as the surviving corporation (which will be renamed American Tower Corporation simultaneous with or immediately following the Merger); 

WHEREAS, American Tower has requested that the Trustee execute and deliver this Supplemental Indenture and the execution and delivery of
this Supplemental Indenture has been duly authorized in all respects; and 
 WHEREAS, all acts and requirements necessary to
make this Supplemental Indenture, when executed and delivered by the parties hereto, the legal, valid and binding obligation of each of American Tower and American Tower REIT, in accordance with its terms, have been done. 

NOW, THEREFORE: 
 Each party agrees as follows for the benefit of the other party and for the equal and ratable benefit of the Holders of the Notes. 
 ARTICLE I ASSUMPTION 
 Section 1.01. ASSUMPTION OF
OBLIGATIONS. 
 Effective as of the Effective Time, American Tower REIT, as the surviving entity in the
Merger, expressly assumes by this Supplemental Indenture all of the obligations of American Tower under the Indenture and the Notes. 







 Section 1.02. SUCCESSOR CORPORATION SUBSTITUTED.

 Effective as of the Effective Time, American Tower REIT shall succeed to, and be substituted for (so that from and after
the Effective Time, the provisions of the Indenture referring to the “Company” shall refer instead to American Tower REIT and not to American Tower), and may exercise every right and power of, American Tower under the Indenture with the
same effect as if American Tower REIT had been named as the Company therein. 
 ARTICLE II MISCELLANEOUS 

Section 2.01. TRUST INDENTURE ACT CONTROLS. 

If any provision of this Supplemental Indenture limits, qualifies or conflicts with the duties imposed by TIA §318(c), the imposed
duties shall control. 
 Section 2.02. COUNTERPART ORIGINALS. 

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. Delivery of an executed counterpart by facsimile shall be effective as delivery of a manually executed counterpart thereof. 
 Section 2.03. GOVERNING LAW. 
 THE INTERNAL
LAW OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED
THEREBY. 
 Section 2.04. NO ADVERSE INTERPRETATION OF OTHER
AGREEMENTS. 
 This Supplemental Indenture may not be used to interpret another indenture, loan or debt
agreement of American Tower, American Tower REIT or any of their respective Subsidiaries or of any other Person. Any such indenture, loan or debt agreement may not be used to interpret this Supplemental Indenture. 

Section 2.05. SEVERABILITY. 
 In case any provision in this Supplemental Indenture shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or
impaired thereby. 
 Section 2.06. HEADINGS. 
 The headings of the Articles and Sections of this Supplemental Indenture have been inserted for convenience of reference only, are not to be considered a part of this Supplemental Indenture and shall in
no way modify or restrict any of the terms or provisions hereof. 
 Section 2.07. NO PERSONAL
LIABILITY OF DIRECTORS, OFFICERS, EMPLOYEES AND STOCKHOLDERS. 
 No past, present or future director, officer, employee, incorporator, stockholder or agent of American Tower or American Tower REIT, as such, shall have any liability for any obligations of American Tower
or American Tower REIT under this Supplemental Indenture or for any claim based on, in respect of, or by reason of, such obligations or their creation. Each Holder by accepting a Note waives and releases all such liability. The waiver and release
are part of the consideration for issuance of the Notes. 

  
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 Section 2.08. PROVISIONS OF SUPPLEMENTAL
INDENTURE FOR THE SOLE BENEFIT OF PARTIES AND HOLDERS. 

Nothing in this Supplemental Indenture, expressed or implied, shall give or be construed to give to any person, firm or corporation, other
than the parties hereto and their successors and the Holders of the Notes, any legal or equitable right, remedy or claim under this Supplemental Indenture or under any covenant or provision herein contained, all such covenants and provisions being
for the sole benefit of the parties hereto and their successors and of the Holders of the Notes. 
 Section 2.09. EXECUTION
AS SUPPLEMENTAL INDENTURE. 
 This Supplemental Indenture is executed and shall
be construed as an indenture supplemental to the Indenture and, as provided in the Indenture, this Supplemental Indenture forms a part thereof. 

Section 2.10. RATIFICATION AND INCORPORATION OF INDENTURE. 

As supplemented hereby, the Indenture is in all respects ratified and confirmed, and the Indenture and this Supplemental Indenture shall
be read, taken and construed as one and the same instrument. 
 Section 2.11. TRUSTEE. 

The Trustee makes no representations as to the validity or adequacy of this Supplemental Indenture, and it shall not be responsible for
any statement or recital herein. 
 [The Remainder of This Page Intentionally Left Blank; Signature Page Follows]


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

					
	AMERICAN TOWER CORPORATION
		
	By:	 	/s/    Edmund DiSanto
		 	Name: 	 	Edmund DiSanto
		 	Title:	 	Executive Vice President, Chief Administrative Officer, General Counsel and Secretary
	
	AMERICAN TOWER REIT, INC.
		
	By:	 	/s/    Thomas A. Bartlett
		 	Name: 	 	Thomas A. Bartlett
		 	Title:	 	Executive Vice President and Chief Financial Officer
	
	 THE BANK OF NEW YORK MELLON TRUST
 COMPANY, N.A., AS TRUSTEE

		
	By:	 	/s/ Raymond K. O’Neil
		 	Name:	 	Raymond K. O’Neil
		 	Title:	 	Senior Associate


 [Second Supplemental Indenture with respect to the October 2007 Indenture]