FOURTH SUPPLEMENTAL INDENTURE SUBSIDIARY GUARANTEE

FOURTH SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as of May 11, 2015, among Dynegy Resource Holdings, LLC, a Delaware limited liability company (the “Guaranteeing Subsidiary”) and a wholly-owned domestic subsidiary of Dynegy Inc. (or its permitted successor), 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”).

WHEREAS, the Company (as successor by merger to Dynegy Finance II, Inc.) has heretofore executed and delivered to the Trustee an indenture (as supplemented, the “Indenture”), dated as of October 27, 2014, among the Company, 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 (the “Initial Notes”) and, subject to the terms of the Indenture, future unlimited issuances of 7.375% Senior Notes due 2022 (the “Additional Notes, and together with the Initial Notes, the “Notes”);

WHEREAS, the Indenture provides that under certain circumstances the Guaranteeing Subsidiary 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 Guarantee”); and

WHEREAS, pursuant to Section 4.07 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 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 Indenture.

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 Indenture. In furtherance of the foregoing, the Guaranteeing Subsidiary shall be deemed a Subsidiary Guarantor for purposes of Article 10 of the Indenture, including, without limitation, Section 10.02 thereof.

3.    NEW YORK LAW TO GOVERN. THE INDENTURE, THE NOTES, THIS SUPPLEMENTAL INDENTURE AND THE SUBSIDIARY GUARANTEE 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.

IN WITNESS WHEREOF, we have hereunto signed our names as of the date set forth below.

Dated: May 11, 2015        

By: /s/ Robert C. Flexon            

Name:     Robert C. Flexon

By: /s/ Robert C. Flexon            

Name:     Robert C. Flexon

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SUBSIDIARY GUARANTORS:

By: /s/ Robert C. Flexon            

Name:     Robert C. Flexon

Title:    Chief Executive Officer

By: /s/ Robert C. Flexon            

Name:    Robert C. Flexon

By: /s/ Robert C. Flexon            

Name:     Robert C. Flexon

Title:    Chief Executive Officer

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By: /s/ Robert C. Flexon            

Name:    Robert C. Flexon

Title:    President & Chief Executive Officer

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By: /s/ Robert C. Flexon            

Name:     Robert C. Flexon

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as Trustee

By: /s/ Boris Treyger            

Name:     Boris Treyger

Title:    Vice President