Tenth Supplemental Indenture for 3.55% Senior Secured Notes due 2024, 3.70% Senior Secured Notes due 2027 and 4.30% Senior Secured Notes due 2029, dated as of December 28, 2021, among Vistra Operations Company LLC, as Issuer, the Guaranteeing Subsidiaries, the Subsidiary Guarantors and the Trustee

TENTH SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as of December 28, 2021, among the subsidiary guarantor listed on Schedule I hereto (the “Guaranteeing Subsidiary”), Vistra Operations Company LLC, a Delaware limited liability company (the “Company”), the other subsidiary guarantors party hereto and Wilmington Trust, National Association, as trustee under the indenture referred to below (the “Trustee”).

WHEREAS, the Company has heretofore executed and delivered to the Trustee (i) that certain Indenture (the “Base Indenture”), dated as of June 11, 2019, among the Company and the Trustee, (ii) that certain Supplemental Indenture (the “First Supplement”), dated as of June 11, 2019, among the Company, the Subsidiary Guarantors party thereto and the Trustee, providing for the original issuance of an aggregate principal amount of $1,200,000,000 of 3.55% Senior Secured Notes due 2024 (the “2024 Notes”) and aggregate principal amount of $800,000,000 of 4.30% Senior Secured Notes due 2029 (the “2029 Notes”), (iii) that certain Second Supplemental Indenture, dated as of August 30, 2019, among the Company, the Subsidiary Guarantors party thereto and the Trustee (the “Second Supplement”), (iv) that certain Third Supplemental Indenture, dated as of October 25, 2019, among the Company, the Subsidiary Guarantors party thereto and the Trustee (the “Third Supplement”), (v) that certain Fourth Supplemental Indenture, dated as of November 15, 2019, among the Company, the Subsidiary Guarantors party thereto and the Trustee, providing for the issuance of $800,000,000 of 3.70% Senior Secured Notes due 2027 (the “2027 Notes” and, collectively with the 2024 Notes and the 2029 Notes, the “Notes”) (the “Fourth Supplement”), (vi) that certain Fifth Supplemental Indenture, dated as of January 31, 2020, among the Company, the Subsidiary Guarantors party thereto and the Trustee (the “Fifth Supplement”, (vii) that certain Sixth Supplemental Indenture, dated as of March 26, 2020, among the Company, the Subsidiary Guarantors party thereto and the Trustee (the “Sixth Supplement”), (viii) that certain Seventh Supplemental Indenture, dated as of October 7, 2020, among the Company, the Subsidiary Guarantors party thereto and the Trustee (the “Seventh Supplement”), (ix) that certain Eighth Supplemental Indenture, dated as of January 8, 2021, among the Company, the Subsidiary Guarantors party thereto and the Trustee (the “Eighth Supplement”), and (x) that certain Ninth Supplemental Indenture, dated as of July 29, 2021, among the Company, the Subsidiary Guarantors party thereto and the Trustee (the “Ninth Supplement” and, together with the Base Indenture, the First Supplement, the Second Supplement, the Third Supplement, the Fourth Supplement, the Fifth Supplement, the Sixth Supplement, the Seventh Supplement, and the Eighth Supplement, the “Indenture”);

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 Subsidiary shall unconditionally guarantee all of the Company’s Obligations under the Notes and the Indenture (the “Subsidiary Guarantees”); and

WHEREAS, pursuant to Section 9.01 of the Base Indenture and Sections 4.07 and 9.01 of the First Supplement and the Fourth Supplement, 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 Subsidiary, 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 Base Indenture, First Supplement or Fourth Supplement, as applicable.

2.    Agreement to be Bound; Guarantee. The Guaranteeing Subsidiary 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. The Guaranteeing Subsidiary 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 Indentures. In furtherance of the foregoing, the Guaranteeing Subsidiary shall be deemed a Subsidiary Guarantor for purposes of Article 10 of the First Supplement and the Fourth Supplement, including, without limitation, Section 10.02 thereof.

3.    NEW YORK LAW TO GOVERN. THIS SUPPLEMENTAL INDENTURE 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 Subsidiary 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.

By: /s/ Kristopher E. Moldovan