**SUPPLEMENTAL INDENTURE**, dated as of April 14, 2010, among XM SATELITE RADIO INC., a Delawarecorporation (the “Company”), SIRIUS XM RADIO INC., a Delaware corporation(“Sirius”), XM 1500 ECKINGTON LLC, a Delaware limited liability company(“Eckington”), XM INVESTMENT LLC a Delaware limited liability company(“Investment”), XM EMALL INC., a Delaware corporation (“EMall”), XM CAPITALRESOURCES INC., a Delaware corporation (“Capital Resources”), XM INNOVATIONS INC., aDelaware corporation (“Innovations”), EFFANEL MUSIC, INC., a New York corporation (withEckington, Investment, EMall, Capital Resources and Innovations, each an “AdditionalGuarantor”), the other Guarantors (as defined in the Indenture referred to herein) and THEBANKOF NEW YORK MELLON, as trustee (the “Trustee”).          **WHEREAS**, the Company has heretofore executed and delivered to the Trustee an indenture (the“Indenture”), dated as of August 1, 2008, in connection with the issuance of 7%Exchangeable Senior Subordinated Notes due 2014 (the “Notes”);          **WHEREAS**, the Indenture provides that under certain circumstances the Guarantor will executeand deliver to the Trustee a supplemental indenture pursuant to which the Guarantor willunconditionally guarantee all of the Company’s Obligations under the Notes and the Indenture on theterms and conditions set forth herein (the “Note Guarantee”); and          **WHEREAS**, pursuant to Section 8.01 of the Indenture, the Trustee is authorized to execute anddeliver this Supplemental Indenture          **NOW, THEREFORE,**in consideration of the foregoing and for other good and valuableconsideration, the receipt of which is hereby acknowledged, each Guarantor, each AdditionalGuarantor and the Trustee mutually covenant and agree for the equal and ratable benefit of theHolders as follows:          **1. CAPITALIZED TERMS.**Capitalized terms used herein without definition will have the meaningsassigned to them in the Indenture.          **2. AGREEMENT TO GUARANTEE.**Each Additional Guarantor hereby agrees to provide anunconditional Guarantee on the terms and subject to the conditions set forth in the Note Guaranteeand in the Indenture including but not limited to Article 9 thereof.          **3. NO RECOURSE AGAINST OTHERS.**No past, present or future director, officer, employee,incorporator, stockholder or agent of each Guarantor or Additional Guarantor, as such, will haveany liability for any obligations of the Company or any Guarantor or any Additional Guarantor underthe Notes, any Note Guarantees, the Indenture or this Supplemental Indenture or for any claim basedon, in respect of, or by reason of, such obligations or their creation. Each Holder of the Notesby accepting a Note waives and releases all such liability. The waiver and release are part of theconsideration for issuance of the Notes.          **4. GOVERNING LAW.**This Supplemental Indenture and the Notes shall be governed by, andconstrued in accordance with, the laws of the State of New York.          **5. COUNTERPARTS.**The parties may sign any number of copies of this Supplemental Indenture.Each signed copy will be an original, but all of them together represent the same agreement.
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          **6. EFFECT OF HEADINGS.**The Section headings herein are for convenience only and will notaffect the construction hereof.          **7. THE TRUSTEE.**The Trustee will not be responsible in any manner whatsoever for or inrespect of the validity or sufficiency of this Supplemental Indenture or for or in respect of therecitals contained herein, all of which recitals are made solely by each Guarantor, each AdditionalGuarantor and the Company.[*remainder of page intentionally left blank*]
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          IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be dulyexecuted all as of the date first above written.