Exhibit 4.6

SECOND SUPPLEMENTAL INDENTURE

SUBSIDIARY GUARANTEES

SECOND SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as of June 14, 2018, among the Subsidiary Guarantors listed on Schedule I hereto (the “Guaranteeing Subsidiaries”), each a wholly-owned domestic subsidiary of Vistra Energy Corp., a Delaware corporation (the “Company”), the Company, the other 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”).

WITNESSETH

WHEREAS, the Company (as successor by merger to Dynegy Inc.) has heretofore executed and delivered to the Trustee an indenture (as supplemented, the “Indenture”), dated as of August 21, 2017, among the Company, the Subsidiary Guarantors party thereto and the Trustee, providing for the original issuance of an aggregate principal amount of $850,000,000 of 8.125% Senior Notes due 2026 and, subject to the terms of the Indenture, future unlimited issuances of 8.125% Senior Notes due 2026 (collectively, the “Notes”);

WHEREAS, the Indenture provides that under certain circumstances the Guaranteeing Subsidiaries shall execute and deliver to the Trustee a supplemental indenture pursuant to which the Guaranteeing Subsidiaries shall unconditionally guarantee all of the Company’s Obligations under the Notes and the Indenture (the “Subsidiary Guarantees”); and

WHEREAS, pursuant to Sections 4.07 and 9.01 of the Indenture, the Trustee, the Company and the other Subsidiary Guarantors are authorized and required to execute and deliver this Supplemental Indenture.

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

1.    Capitalized Terms. Unless otherwise defined in this Supplemental Indenture, capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture.

2.    Agreement to be Bound; Guarantee. Each of the Guaranteeing Subsidiaries hereby becomes a party to the Indenture as a Subsidiary Guarantor and as such will have all of the rights and be subject to all of the Obligations and agreements of a Subsidiary Guarantor under the Indenture. Each of the Guaranteeing Subsidiaries hereby agrees to be bound by all of the provisions of the Indenture applicable to a Subsidiary Guarantor and to perform all of the Obligations and agreements of a Subsidiary Guarantor under the Indenture. In furtherance of the foregoing, each of the Guaranteeing Subsidiaries shall be deemed a Subsidiary Guarantor for purposes of Article 10 of the Indenture, including, without limitation, Section 10.02 thereof.

1

3.    NEW YORK LAW TO GOVERN. THE INDENTURE, THE NOTES, THIS SUPPLEMENTAL INDENTURE AND THE SUBSIDIARY GUARANTEES SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

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 Guaranteeing Subsidiaries and the Company.

7.    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 Notes heretofore or hereafter authenticated and delivered shall be bound hereby.

[Signature pages follow]

2

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.

BIG BROWN POWER COMPANY LLC BRIGHTEN ENERGY LLC COLETO CREEK POWER, LLC COMANCHE PEAK POWER COMPANY LLC DALLAS POWER & LIGHT COMPANY, INC. ENNIS POWER COMPANY, LLC FORNEY PIPELINE, LLC GENERATION SVC COMPANY HAYS ENERGY, LLC LA FRONTERA HOLDINGS, LLC LONE STAR ENERGY COMPANY, INC. LONE STAR PIPELINE COMPANY, INC. LUMINANT ENERGY COMPANY LLC LUMINANT ENERGY TRADING CALIFORNIA COMPANY LUMINANT ET SERVICES COMPANY LLC LUMINANT GENERATION COMPANY LLC LUMINANT MINING COMPANY LLC MIDLOTHIAN ENERGY, LLC NCA RESOURCES DEVELOPMENT COMPANY LLC OAK GROVE MANAGEMENT COMPANY LLC SANDOW POWER COMPANY LLC SOUTHWESTERN ELECTRIC SERVICE COMPANY, INC. TEXAS ELECTRIC SERVICE COMPANY, INC. TEXAS ENERGY INDUSTRIES COMPANY, INC. TEXAS POWER & LIGHT COMPANY, INC. TEXAS UTILITIES COMPANY, INC. TEXAS UTILITIES ELECTRIC COMPANY, INC. T-FUELS, LLC TXU ELECTRIC COMPANY, INC. TXU ENERGY RETAIL COMPANY LLC TXU RETAIL SERVICES COMPANY UPTON COUNTY SOLAR 2, LLC VALUE BASED BRANDS LLC VISTRA ASSET COMPANY LLC VISTRA CORPORATE SERVICES COMPANY VISTRA EP PROPERTIES COMPANY VISTRA FINANCE CORP. VISTRA INTERMEDIATE COMPANY LLC VISTRA OPERATIONS COMPANY LLC VISTRA PREFERRED INC. WHARTON COUNTY GENERATION, LLC WISE COUNTY POWER COMPANY, LLC WISE-FUELS PIPELINE, INC., as the Guaranteeing Subsidiaries

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

[Signature Page to 2026 Notes Supplemental Indenture]

VISTRA ENERGY CORP., as the Company
By:	/s/ Kristopher E. Moldovan
	Name:	Kristopher E. Moldovan
	Title:	Senior Vice President and Treasurer

[Signature Page to 2026 Notes Supplemental Indenture]

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 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 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 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 the Subsidiary Guarantors

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

[Signature Page to 2026 Notes Supplemental Indenture]

WILMINGTON TRUST, NATIONAL ASSOCIATION, as the Trustee
By:	/s/ Shawn Goffinet
	Name:	Shawn Goffinet
	Title:	Assistant Vice President

[Signature Page to 2026 Notes Supplemental Indenture]

SCHEDULE I

SUBSIDIARY GUARANTORS

BIG BROWN POWER COMPANY LLC

BRIGHTEN ENERGY LLC

COLETO CREEK POWER, LLC

COMANCHE PEAK POWER COMPANY LLC

DALLAS POWER & LIGHT COMPANY, INC.

ENNIS POWER COMPANY, LLC

FORNEY PIPELINE, LLC

GENERATION SVC COMPANY

HAYS ENERGY, LLC

LA FRONTERA HOLDINGS, LLC

LONE STAR ENERGY COMPANY, INC.

LONE STAR PIPELINE COMPANY, INC.

LUMINANT ENERGY COMPANY LLC

LUMINANT ENERGY TRADING CALIFORNIA COMPANY

LUMINANT ET SERVICES COMPANY LLC

LUMINANT GENERATION COMPANY LLC

LUMINANT MINING COMPANY LLC

MIDLOTHIAN ENERGY, LLC

NCA RESOURCES DEVELOPMENT COMPANY LLC

OAK GROVE MANAGEMENT COMPANY LLC

SANDOW POWER COMPANY LLC

SOUTHWESTERN ELECTRIC SERVICE COMPANY, INC.

TEXAS ELECTRIC SERVICE COMPANY, INC.

TEXAS ENERGY INDUSTRIES COMPANY, INC.

TEXAS POWER & LIGHT COMPANY, INC.

TEXAS UTILITIES COMPANY, INC.

TEXAS UTILITIES ELECTRIC COMPANY, INC.

T-FUELS, LLC

TXU ELECTRIC COMPANY, INC.

TXU ENERGY RETAIL COMPANY LLC

TXU RETAIL SERVICES COMPANY

UPTON COUNTY SOLAR 2, LLC

VALUE BASED BRANDS LLC

VISTRA ASSET COMPANY LLC

VISTRA CORPORATE SERVICES COMPANY

VISTRA EP PROPERTIES COMPANY

VISTRA FINANCE CORP.

VISTRA INTERMEDIATE COMPANY LLC

VISTRA OPERATIONS COMPANY LLC

VISTRA PREFERRED INC.

WHARTON COUNTY GENERATION, LLC

WISE COUNTY POWER COMPANY, LLC

WISE-FUELS PIPELINE, INC.

Sch-I-1