Third Supplemental Indenture



 Exhibit 4.21 
 THIRD SUPPLEMENTAL INDENTURE 
 THIRD SUPPLEMENTAL
INDENTURE (this “Supplemental Indenture”), dated as of August 4, 2009, among Kaiser Trading, LLC, an Oklahoma limited liability company (the “New Guarantor”), Petrohawk Energy Corporation, a Delaware
corporation (the “Company”), the existing Guarantors (as defined in the Indenture referred to herein) and U.S. Bank Trust National Association, as trustee under the Indenture referred to herein (the “Trustee”). The
New Guarantor and the existing Guarantors are sometimes referred to collectively herein as the “Guarantors,” or individually as a “Guarantor.” 
 W I T N E S S E T H 
 WHEREAS, the Company and the
existing Guarantors have heretofore executed and delivered to the Trustee an indenture (the “Indenture”), dated as of May 13, 2008, relating to the 7.875% Senior Notes due 2015 (the “Securities”) of the
Company; 
 WHEREAS, Section 4.9 of the Indenture provides that if the Company or any of its Restricted Subsidiaries
acquires or creates another Restricted Subsidiary (other than Foreign Subsidiaries) after the Issue Date, then the Company shall cause newly acquired or created Restricted Subsidiary (i) to become a Guarantor by executing a supplemental
indenture and (ii) to deliver an Opinion of Counsel to the Trustee as provided in such Section; and 
 WHEREAS, pursuant to
Section 9.1 of the Indenture, the Company, the Guarantors and the Trustee are authorized to execute and deliver this Supplemental Indenture to amend or supplement the Indenture without the consent of any Holder. 
 NOW THEREFORE, to comply with the provisions of the Indenture and in consideration of the foregoing and for other good and valuable
consideration, the receipt of which is hereby acknowledged, the New Guarantor, the other Guarantors, the Company and the Trustee mutually covenant and agree for the equal and ratable benefit of the Holders of the Securities as follows: 

1. CAPITALIZED TERMS. Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture.

 2. AGREEMENT TO GUARANTEE. The New Guarantor hereby agrees, jointly and severally, with all other Guarantors, to
unconditionally Guarantee to each Holder and to the Trustee the Obligations, to the extent set forth in the Indenture and subject to the provisions in the Indenture. The obligations of the Guarantors to the Holders of Securities and to the Trustee
pursuant to the Subsidiary Guarantees and the Indenture are expressly set forth in Article X of the Indenture and reference is hereby made to the Indenture for the precise terms of the Subsidiary Guarantees. 
 3. EXECUTION AND DELIVERY. The New Guarantor agrees that its Subsidiary Guarantee shall remain in full force and effect notwithstanding any
failure to endorse on each Security a notation of such Subsidiary Guarantee. 







 4. NEW YORK LAW TO GOVERN. THE LAWS OF THE STATE OF NEW YORK SHALL GOVERN AND BE USED TO
CONSTRUE AND ENFORCE THIS SUPPLEMENTAL INDENTURE. 
 5. 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. This Supplemental Indenture may be executed in multiple counterparts which, when taken together, shall constitute one instrument.

 6. EFFECT OF HEADINGS. The Section headings herein are for convenience only and shall not affect the construction hereof.

 7. THE TRUSTEE. Except as otherwise expressly provided herein, no duties, responsibilities or liabilities are assumed, or
shall be construed to be assumed, by the Trustee by reason of this Supplemental Indenture. This Supplemental Indenture is executed and accepted by the Trustee subject to all the terms and conditions set forth in the Indenture with the same force and
effect as if those terms and conditions were repeated at length herein and made applicable to the Trustee with respect hereto. 
 [Remainder of Page Intentionally Left Blank; Signature Page Follows] 
  
  
  

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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. 
  

			
	PETROHAWK ENERGY CORPORATION
	KAISER TRADING, LLC
	PETROHAWK HOLDINGS, LLC
	P-H ENERGY, LLC
	PETROHAWK OPERATING COMPANY
	HAWK FIELD SERVICES, L.L.C.
	WINWELL RESOURCES, L.L.C.
	WSF, INC.
	KCS RESOURCES, LLC
	KCS ENERGY SERVICES, INC.
	 MEDALLION CALIFORNIA PROPERTIES COMPANY

	PROLIQ, INC.
	ONE TEC, LLC
	ONE TEC OPERATING, LLC
	BISON RANCH LLC
		
	By:	 	/s/ David S. Elkouri
		 	David S. Elkouri
		 	 Executive Vice President –
General Counsel and Secretary

	
	HK ENERGY MARKETING, LLC
		
	By:	 	/s/ David S. Elkouri
		 	David S. Elkouri
		 	 Secretary

	
	PETROHAWK PROPERTIES, LP
		
	By:	 	 P-H Energy, LLC
 Its General
Partner

		
	By:	 	/s/ David S. Elkouri
		 	David S. Elkouri
		 	 Executive Vice President –
General Counsel and Secretary



  

 SIGNATURE PAGE OF THIRD
SUPPLEMENTAL INDENTURE 








 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. 
  

			
	 U.S. BANK TRUST NATIONAL ASSOCIATION,
as Trustee

		
	By:	 	/s/ William W. MacMillan
	Name:	 	William W. MacMillan
	Title:	 	 Vice President



  

 SIGNATURE PAGE OF THIRD
SUPPLEMENTAL INDENTURE