EX-4.19



 Exhibit 4.19 

EIGHTH SUPPLEMENTAL INDENTURE 
 TO
BE DELIVERED IN CONNECTION WITH THE VISTRA ACQUISITION 
 EIGHTH SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as
of April 9, 2018, between Vistra Energy Corp., a Delaware corporation (the “Successor”), the Subsidiary Guarantors (as defined in the Indenture referred to herein) and Wilmington Trust, National Association, as trustee under the
indenture referred to below (the “Trustee”). Unless otherwise defined in this Supplemental Indenture, capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture (as defined below). 

WITNESSETH 
 WHEREAS, Dynegy Inc.
(as successor by merger to Dynegy Finance II, Inc.) (“Dynegy”) has heretofore executed and delivered to the Trustee an indenture (as supplemented from time to time prior to the date hereof, the “Indenture”), dated as of
October 27, 2014, among Dynegy, the Subsidiary Guarantors named therein and the Trustee, providing for the original issuance of an aggregate principal amount of $1,050,000,000 of 7.375% Senior Notes due 2022 and, subject to the terms of the
Indenture, future unlimited issuances of 7.375% Senior Notes due 2022 (the “2022 Notes”); 
 WHEREAS, the Successor has filed with
the Secretary of State of the State of Delaware a Certificate of Merger, dated as of April 9, 2018, which provides for the merger of Dynegy with and into the Successor (the “Merger”), with the Successor continuing its corporate
existence under the laws of the State of Delaware as the surviving company of the Merger; 
 WHEREAS, Section 5.01 of the Indenture
provides, among other things, that Dynegy may consolidate or merge with or into another Person; provided that, among other things, the Person formed by or surviving any such consolidation or merger (if other than Dynegy) assumes all the
obligations of Dynegy under the Indenture and the 2022 Notes pursuant to a supplemental indenture; 
 WHEREAS, Section 9.01 of the
Indenture provides, among other things, that the Indenture and the 2022 Notes may be amended or supplemented without the consent of any Holder to provide for the assumption of Dynegy’s obligations to Holders of the 2022 Notes in the case of a
merger or consolidation; and 
 WHEREAS, the Successor desires and has requested that the Trustee join in the execution of this Supplemental
Indenture for the purpose of evidencing such assumption by the Successor. 

  
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 NOW THEREFORE, in consideration of the foregoing and for good and valuable consideration, the
receipt of which is hereby acknowledged, the Trustee and the Successor mutually covenant and agree for the equal and ratable benefit of the Holders of the 2022 Notes as follows: 

ARTICLE 1 
 ASSUMPTION AND
AGREEMENTS 
 Section 1.1. The Successor hereby, in accordance with the terms and conditions of the Indenture,
assumes the due and punctual payment of the principal of, premium, if any, and interest on the 2022 Notes, and the due and punctual performance and observance of all other covenants, conditions and other obligations contained in the Indenture and
the 2022 Notes on the part of Dynegy to be performed or observed. 
 Section 1.2. The Successor shall succeed to,
and be substituted for, and may exercise every right and power of, Dynegy under the Indenture and the 2022 Notes, with the same effect as if the Successor had been named as “the Company” therein. 

ARTICLE 2 
 MISCELLANEOUS 

Section 2.1. NEW YORK LAW TO GOVERN. THE INDENTURE, THIS SUPPLEMENTAL INDENTURE AND THE 2022 NOTES SHALL BE GOVERNED
BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK. 
 Section 2.2. 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. 

Section 2.3. Effect of Headings. The Section headings herein are for convenience only and shall not affect the
construction hereof. 
 Section 2.4. 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 Successor. 

Section 2.5. Ratification of Indenture; Supplemental Indenture 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 the 2022 Notes heretofore or hereafter authenticated and delivered shall be bound hereby. 
 [Signature pages follow] 

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

			
	VISTRA ENERGY CORP., as Successor
		
	By:	 	 /s/ Kristopher E. Moldovan

	Name:	 	 Kristopher E. Moldovan

	Title:	 	 Senior Vice President and Treasurer


 ANP BELLINGHAM ENERGY COMPANY, LLC 

ANP BLACKSTONE ENERGY COMPANY, LLC 
 CALUMET ENERGY
TEAM, LLC 
 CASCO BAY ENERGY COMPANY, LLC 

COFFEEN AND WESTERN RAILROAD COMPANY 
 DYNEGY
ADMINISTRATIVE SERVICES COMPANY 
 DYNEGY ASSOCIATES NORTHEAST LP, INC. 

DYNEGY COAL GENERATION, LLC 
 DYNEGY COAL HOLDCO, LLC

 DYNEGY COAL TRADING & TRANSPORTATION, L.L.C. 

DYNEGY COMMERCIAL ASSET MANAGEMENT, LLC 
 DYNEGY
CONESVILLE, LLC 
 DYNEGY DICKS CREEK, LLC 

DYNEGY ENERGY SERVICES (EAST), LLC 
 DYNEGY ENERGY
SERVICES, LLC 
 DYNEGY FAYETTE II, LLC 
 DYNEGY
GAS IMPORTS, LLC 
 DYNEGY GLOBAL LIQUIDS, INC. 

DYNEGY HANGING ROCK II, LLC 
 DYNEGY KENDALL ENERGY, LLC

 DYNEGY KILLEN, LLC 
 DYNEGY MARKETING AND
TRADE, LLC 
 DYNEGY MIAMI FORT, LLC 
 DYNEGY
MIDWEST GENERATION, LLC 
 DYNEGY MORRO BAY, LLC 

DYNEGY MOSS LANDING, LLC 
 DYNEGY NORTHEAST GENERATION
GP, INC. 
 DYNEGY OAKLAND, LLC 
 DYNEGY OPERATING
COMPANY 
 DYNEGY POWER GENERATION INC. 
 DYNEGY
POWER MARKETING, LLC 
 DYNEGY POWER, LLC 

[Signature Page to 2022 Notes Supplemental Indenture] 







 DYNEGY RESOURCE II, LLC 

DYNEGY RESOURCES GENERATING HOLDCO, LLC 
 DYNEGY SOUTH
BAY, LLC 
 DYNEGY STUART, LLC 
 DYNEGY WASHINGTON
II, LLC 
 DYNEGY ZIMMER, LLC 
 EQUIPOWER
RESOURCES CORP. 
 HAVANA DOCK ENTERPRISES, LLC 

HOPEWELL POWER GENERATION, LLC 
 ILLINOIS POWER
GENERATING COMPANY 
 ILLINOIS POWER MARKETING COMPANY 

ILLINOIS POWER RESOURCES GENERATING, LLC 
 ILLINOIS
POWER RESOURCES, LLC 
 ILLINOVA CORPORATION 

IPH, LLC 
 IPH II, LLC 

KINCAID GENERATION, L.L.C. 
 LAKE ROAD GENERATING
COMPANY, LLC 
 LIBERTY ELECTRIC POWER, LLC 

MASSPOWER, LLC 
 MILFORD POWER COMPANY, LLC 

NEPCO SERVICES COMPANY 
 NORTHEASTERN POWER COMPANY

 ONTELAUNEE POWER OPERATING COMPANY, LLC 

PLEASANTS ENERGY, LLC 
 RICHLAND-STRYKER GENERATION, LLC

 SITHE ENERGIES, INC. 
 SITHE/INDEPENDENCE LLC,


			
	as Subsidiary Guarantors
		
	By:	 	 /s/ Kristopher E. Moldovan

	Name:	 	Kristopher E. Moldovan
	Title:	 	Senior Vice President and Treasurer

 [Signature Page to 2022 Notes Supplemental Indenture] 








			
	WILMINGTON TRUST, NATIONAL ASSOCIATION,
	as Trustee
		
	By:	 	 /s/ Shawn Goffinet

	Name:	 	 Shawn Goffinet

	Title:	 	 Assistant Vice President


 [Signature Page to 2022 Notes Supplemental Indenture]