Third Supplemental Indenture



 Exhibit 4(a) 
 EXECUTION VERSION 
 THIRD SUPPLEMENTAL INDENTURE 

Third Supplemental Indenture (this “Supplemental Indenture”), dated as of September 26, 2011, among Texas
Competitive Electric Holdings Company LLC, a Delaware limited liability company, and TCEH Finance, Inc., a Delaware corporation (collectively, the “Issuer”), the Guarantors named on the signature pages hereto (the
“Guarantors”) and The Bank of New York Mellon Trust Company, N.A., as Trustee (the “Trustee”). 

W I T N E S S E T H 
 WHEREAS, each of the Issuer and the Guarantors has heretofore executed and delivered to the Trustee an Indenture, dated as of October 6, 2010 (the “Original Indenture”), providing
for the issuance of $335,905,000 in aggregate principal amount of 15% Senior Secured Second Lien Notes due 2021 (the “Initial Second Lien Notes”), a First Supplemental Indenture, dated as of October 20, 2010 (the “First
Supplemental Indenture”), providing for the issuance of $350,000,000 aggregate principal amount of 15% Senior Secured Second Lien Notes due 2021, Series B (the “Initial Series B Second Lien Notes”), and a Second
Supplemental Indenture, dated as of November 15, 2010 (together with the Original Indenture and the First Supplemental Indenture, the “Indenture”), providing for the issuance of $884,780,000 aggregate principal amount of
Additional Series B Second Lien Notes (the “Additional Series B Second Lien Notes” and, together with the Initial Second Lien Notes and the Initial Series B Second Lien Notes, the “Notes”), and an unlimited
aggregate principal amount of Additional Notes subsequent to the Issue Date; 
 WHEREAS, on October 6, 2010, the Issuer
issued and sold the Initial Second Lien Notes, on October 20, 2010, the Issuer issued and sold the Initial Series B Second Lien Notes and on November 15, 2010, the Issuer issued and sold the Additional Series B Second Lien Notes;

 WHEREAS, pursuant to Section 9.01(12) of the Original Indenture, the Issuer, the Guarantors and the Trustee are
authorized to execute and deliver this Supplemental Indenture; 
 WHEREAS, the Issuer has delivered to the Trustee an
Officer’s Certificate as well as an Opinion of Counsel to the effect that the execution and delivery of this Supplemental Indenture by the Issuer is authorized or permitted under the Indenture and that all conditions precedent provided for in
the Indenture to the execution and delivery of this Supplemental Indenture to be complied with by the Issuer have been complied with; 
 WHEREAS, each of the Issuer and each Guarantor has been authorized by resolution of its Board of Directors to enter into this Supplemental Indenture; and 

WHEREAS, all conditions necessary to authorize the execution and delivery of this Supplemental Indenture by the Issuer and the Guarantors
and to make this Supplemental Indenture valid and binding on the Issuer and the Guarantors have been complied with or have been done or performed. 







 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 Notes as follows: 
 ARTICLE ONE 
 SECTION 1.01. CAPITALIZED
TERMS. Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture. 
 ARTICLE TWO 
 SECTION 2.01. AMENDMENT. For the avoidance of
doubt, Section 2.06 of the Indenture is amended to add at the end of that section a new clause (j) reading as follows: 
 (j) Automatic Exchange from Restricted Global Notes or Restricted Definitive Notes to Unrestricted Global Notes. At the option of the Issuer and upon compliance with the following procedures,
beneficial interests in one or more Restricted Global Notes or Restricted Definitive Notes shall be exchanged for beneficial interests in an Unrestricted Global Note. In order to effect such exchange, the Issuer shall provide written notice to the
Trustee instructing the Trustee to (i) direct the Depositary to transfer the specified amount of the outstanding beneficial interests in one or more Restricted Global Notes or Restricted Definitive Notes to one or more Unrestricted Global Notes
and provide the Depositary with all such information as is necessary for the Depositary to appropriately credit and debit the relevant Holder accounts and (ii) provide written notice prepared by the Issuer to the Depositary and the Holders of
the applicable Restricted Global Notes or Restricted Definitive Notes of such exchange, which notice must include the date of such exchange, the CUSIP number of the relevant Restricted Global Notes or Restricted Definitive Notes and the CUSIP number
of the Unrestricted Global Notes into which such Holders’ beneficial interests are exchanged. As a condition to any exchange pursuant to this Section 2.06(j), the Trustee shall be entitled to receive from the Issuer, and rely upon
conclusively without liability, an Officer’s Certificate and an Opinion of Counsel to the effect that such transfer of beneficial interests to the Unrestricted Global Notes shall be effected in compliance with the Securities Act. The Issuer may
request from any Holder such information it reasonably determines is required in order to be able to deliver such Officer’s Certificate and Opinion of Counsel. If any such transfer or exchange is effected pursuant to this Section 2.06(j)
at a time when an Unrestricted Global Note has not yet been issued, the Issuer shall issue and, upon receipt of a written order of the Issuer signed by an Officer in accordance with Section 2.02 hereof, the Trustee shall authenticate one or
more Unrestricted Global Notes in an aggregate principal amount equal to the aggregate principal amount of beneficial interests transferred or exchanged pursuant to this Section 2.06(j). Upon an exchange pursuant to this Section 2.06(j),
the Registrar shall reflect on its books and records the date of such transfer and a decrease and increase, respectively, in the principal amount of the applicable Restricted Global Notes or Restricted Definitive Notes and the Unrestricted Global
Notes, respectively, equal to the principal amount of beneficial interests transferred. Following any transfer pursuant to this Section 2.06(j) of all of the beneficial interests in a Restricted Global Note or Restricted Definitive Note, such
Restricted Global Note or Restricted Definitive Note shall be cancelled. 

  
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 ARTICLE THREE 

SECTION 3.01. GOVERNING LAW. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF
NEW YORK. 
 ARTICLE FOUR 
 SECTION 4.01. FULL FORCE AND EFFECT. Except as expressly supplemented or 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. Upon the execution and delivery of this Supplemental Indenture by the Issuer, the Guarantors and the Trustee, this Supplemental Indenture shall form a part
of the Indenture for all purposes, and the Issuer, the Guarantors and the Trustee and every Holder of Notes heretofore or hereafter authenticated and delivered shall be bound hereby. Any and all references to the Indenture, whether within the
Indenture or in any notice, certificate or other instrument or document, shall be deemed to include a reference to this Supplemental Indenture (whether or not made), unless the context shall otherwise require. 

SECTION 4.02. INDENTURE AND SUPPLEMENTAL INDENTURE CONSTRUED
TOGETHER. This Supplemental Indenture is an indenture supplemental to the Indenture, and the Indenture and this Supplemental Indenture shall henceforth be read and construed together. 

SECTION 4.03. CONFIRMATION AND PRESERVATION OF INDENTURE. The
Indenture as supplemented or amended by this Supplemental Indenture is in all respects confirmed and preserved. 
 SECTION 4.04.
BENEFITS OF SUPPLEMENTAL INDENTURE. Nothing in this Supplemental Indenture, express or implied, shall give to any Person other than the parties hereto and thereto and their successors
hereunder and thereunder and the Holders of the Notes, any benefit of any legal or equitable right, remedy or claim under the Indenture, this Supplemental Indenture or the Notes. 

SECTION 4.05. SUCCESSORS. All agreements of the Issuer and the Guarantors in this Supplemental Indenture shall bind their
respective successors. All agreements of the Trustee in this Supplemental Indenture shall bind its successors. 
 SECTION 4.06.
THE TRUSTEE. The Trustee shall not be responsible in any manner 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 are
made by the Issuer and the Guarantors. 
 SECTION 4.07. 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. 

  
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 SECTION 4.08. EFFECT OF HEADINGS. The Section
headings herein are for convenience only and shall not affect the construction hereof. 
 SECTION 4.09.
SEVERABILITY. If any provision in this Supplemental Indenture shall be invalid, illegal or unenforceable, the validity, legality or enforceability of the remaining provisions of this Supplemental Indenture or the Indenture shall not
in any way be affected or impaired thereby. 
 [Remainder of Page Left Intentionally Blank] 

  
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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. 
  

					
	TEXAS COMPETITIVE ELECTRIC HOLDINGS COMPANY LLC
		
	 By:
	 	 /s/ Anthony R. Horton

		 	Name:	 	Anthony R. Horton
		 	Title:	 	Treasurer
	
	TCEH FINANCE, INC.
		
	 By:
	 	 /s/ Anthony R. Horton

		 	Name:	 	Anthony R. Horton
		 	Title:	 	Treasurer
	
	ENERGY FUTURE COMPETITIVE HOLDINGS COMPANY
		
	 By:
	 	 /s/ Anthony R. Horton

		 	Name:	 	Anthony R. Horton
		 	Title:	 	Treasurer
	
	BIG BROWN 3 POWER COMPANY LLC
	BIG BROWN LIGNITE COMPANY LLC
	BIG BROWN POWER COMPANY LLC
	COLLIN POWER COMPANY LLC
	DECORDOVA POWER COMPANY LLC
	GENERATION MT COMPANY LLC
	GENERATION SVC COMPANY
	LAKE CREEK 3 POWER COMPANY LLC
	LUMINANT BIG BROWN MINING COMPANY LLC
	LUMINANT ENERGY COMPANY LLC
	LUMINANT ENERGY SERVICES COMPANY
	LUMINANT ENERGY TRADING CALIFORNIA COMPANY



  
 [Signature
page to Third Supplemental Indenture] 









					
	LUMINANT ET SERVICES COMPANY
	LUMINANT GENERATION COMPANY LLC
	LUMINANT HOLDING COMPANY LLC
	LUMINANT MINERAL DEVELOPMENT COMPANY LLC
	LUMINANT MINING COMPANY LLC
	LUMINANT MINING SERVICES COMPANY
	LUMINANT POWER SERVICES COMPANY
	LUMINANT RENEWABLES COMPANY LLC
	MARTIN LAKE 4 POWER COMPANY LLC
	MONTICELLO 4 POWER COMPANY LLC
	MORGAN CREEK 7 POWER COMPANY LLC
	NCA RESOURCES DEVELOPMENT COMPANY LLC
	OAK GROVE MANAGEMENT COMPANY LLC
	OAK GROVE MINING COMPANY LLC
	OAK GROVE POWER COMPANY LLC
	SANDOW POWER COMPANY LLC
	TRADINGHOUSE 3 & 4 POWER COMPANY LLC
	TRADINGHOUSE POWER COMPANY LLC
	TXU ENERGY RETAIL COMPANY LLC
	TXU ENERGY SOLUTIONS COMPANY LLC
	TXU RETAIL SERVICES COMPANY
	TXU SEM COMPANY
	TXU SESCO COMPANY LLC
	TXU SESCO ENERGY SERVICES COMPANY
	VALLEY NG POWER COMPANY LLC
	VALLEY POWER COMPANY LLC
		
	By:	 	 /s/ Anthony R. Horton

		 	Name:	 	Anthony R. Horton
		 	Title:	 	Treasurer
	
	THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., as Trustee
		
	By:	 	 /s/ Julie Hoffman-Ramos

		 	Name:	 	Julie Hoffman-Ramos
		 	Title:	 	Vice President



  
 [Signature
page to Third Supplemental Indenture]