EX-4.18



 Exhibit 4.18 

EXECUTION VERSION 
 SECOND
SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as of August 9, 2016, by and between The ADT Corporation, a Delaware corporation (the “Company”), the Notes Guarantors listed on the signature pages
hereto (the “Notes Guarantors”) and Wells Fargo Bank, National Association, as trustee (the “Trustee”). 

W I T N E S S E T H 

WHEREAS, Prime Security One MS, Inc., as predecessor in interest to the Company, and the Trustee executed and delivered an indenture (as
amended or supplemented prior to the date hereof, the “Base Indenture”), dated as of May 2, 2016, providing for the issuance of 4.875% First-Priority Senior Secured Notes due 2032 (the “Existing Securities”);

 WHEREAS, the Company, the Notes Guarantors and the Trustee executed and delivered a supplemental indenture (as amended or supplemented
prior to the date hereof, the “First Supplemental Indenture” and, together with the Base Indenture, the “Indenture”), dated as of May 2, 2016; 

WHEREAS, Section 2.01 of the Indenture provides that additional Securities of any particular series may be issued from time to time by
the Company; 
 WHEREAS, the Company and the Notes Guarantors desire to execute and deliver this Supplemental Indenture for the purpose of
issuing $9,750,000 in aggregate principal amount of additional first-priority senior secured debt securities, having terms substantially identical in all material respects to the Existing Securities (the “Additional Securities” and,
together with the Existing Securities, the “Securities”); and 
 WHEREAS, pursuant to Section 10.01 of the Indenture,
the Company, the Notes Guarantors and the Trustee are authorized to execute and deliver this Supplemental Indenture without the consent of the holders of the Existing Securities. 

NOW THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged,
the parties mutually covenant and agree for the equal and ratable benefit of the holders of the Securities as follows: 

(1) Capitalized Terms. Capitalized terms used herein without definition shall have the meanings assigned to them in
the Indenture. 
 (2) Additional Securities. As of the date hereof, the Company will issue, and the Trustee is
directed to authenticate and deliver, the Additional Securities under the Indenture, having terms substantially identical in all material respects to the Existing Securities (including accruing interest from May 2, 2016). The Existing
Securities and the Additional Securities shall be treated as a single class for all purposes under the Indenture. 
 (3)
Governing Law. THIS SUPPLEMENTAL INDENTURE WILL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, AND FOR ALL PURPOSES SHALL BE CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO
CONFLICTS OF LAWS PRINCIPLES THAT WOULD REQUIRE THE APPLICATION OF ANY OTHER LAW. 







 (4) 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. 
 (5)
Effect of Headings. The Section headings herein are for convenience only and shall not affect the construction hereof. 

(6) The Trustee. The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or
sufficiency of this Supplemental Indenture or for or in respect of the recitals contained herein, all of which recitals are made solely by the Company and the Notes Guarantors. 

(7) Continued Effect. Except as expressly supplemented and amended by this Supplemental Indenture, the Indenture shall
continue in full force and effect in accordance with the provisions thereof, and the Indenture (as supplemented and amended by this Supplemental Indenture) is in all respects hereby ratified and confirmed. This Supplemental Indenture and all the
terms and conditions of this Supplemental Indenture, with respect to the Securities, shall be and be deemed to be part of the terms and conditions of the Indenture for any and all purposes. 

[The remainder of this page is intentionally left blank.] 







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

			
	Very truly yours,
	
	THE ADT CORPORATION
		
	By:	 	 /s/ Timothy J. Wall

		 	Name: Timothy J. Wall
		 	Title: President and Chief Executive Officer


 [Signature Page to Supplemental Indenture] 







 
					
	 Notes Guarantors:

	
	PRIME SECURITY SERVICES BORROWER, LLC
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	PRIME FINANCE INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	ASG INTERMEDIATE HOLDING CORP.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	ASG HOLDINGS LLC
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	ALARM SECURITY GROUP LLC
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer


 [Signature
Page to Supplemental Indenture] 







 
					
	ABC SECURITY CORPORATION
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	BRINKMAN SECURITY, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	ASG GOVERNMENT SERVICES LLC
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	NOLAN’S PROTECTION SYSTEMS, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	PROTECTION HOLDINGS II, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer


 [Signature
Page to Supplemental Indenture] 







 
					
	PROTECTION ONE, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	PROTECTION ONE ALARM MONITORING, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	SECURITY MONITORING SERVICES, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	Vice President
	
	PROTECTION ONE SYSTEMS, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	PROTECTION ONE DATA SERVICES, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer


 [Signature
Page to Supplemental Indenture] 







 
					
	PROTECTION ONE ALARM MONITORING OF MASS., INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	MONITAL SIGNAL CORPORATION
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President and Chief Executive Officer
	
	ADT CANADA HOLDINGS, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President
	
	ADT HOLDINGS, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President
	
	ADT US HOLDINGS, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President


 [Signature Page to Supplemental
Indenture] 







 
					
	ADT INVESTMENTS, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President
	
	ADT LLC
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President
	
	ELECTRO SIGNAL LAB, INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President
	
	S2 MERGERSUB INC.
		
	By:	 	 /s/ Timothy J. Whall

		 	Name:	 	Timothy J. Whall
		 	Title:	 	President


 [Signature Page to Supplemental
Indenture] 







 
					
	WELLS FARGO BANK, NATIONAL ASSOCIATION, as Trustee
		
	By:	 	 /s/ Martin Reed

		 	Name:	 	Martin Reed
		 	Title:	 	Vice President


 [Signature Page to Supplemental
Indenture]