Amendment No. 1 to Registration Rights Agreement



     THIS AMENDMENT NO. 1 TO (this “Amendment”)is made and enacted as of April 28, 2006 by XO Holdings, Inc., a Delaware corporation (the“Company”).
R E C I T A L S:
     WHEREAS, on August 5, 2004, XO Communications, Inc., a Delaware corporation (the“Predecessor Issuer”), entered into a (the “”) with the purchasers of its 6% Class A Convertible Preferred Stock, providingfor the registration of Registrable Securities (as defined in the )pursuant to the Securities Act of 1933, as amended;
     WHEREAS, on February 28, 2006, the Predecessor Issuer consummated a corporate restructuringpursuant to which the Predecessor Issuer merged (the “Restructuring Merger”) with and intoits then indirect wholly owned subsidiary, XO Communications, LLC, with such subsidiary as theentity surviving such merger as a direct wholly owned subsidiary of the Company;
     WHEREAS, pursuant to the Restructuring Merger, among other things, all of the capital stockand other securities of the Predecessor Issuer, including the Registrable Securities, wereconverted into the right to receive corresponding capital stock and other securities of the Companyon a one-for-one basis, and the Company assumed the rights and obligations of the PredecessorIssuer under the ; and
     WHEREAS, the Company desires to amend the as provided hereinpursuant to Section 4 thereof;
     NOW, THEREFORE, in consideration of the foregoing premises and for other good and valuableconsideration, the receipt and sufficiency of which are hereby acknowledged, the Company, intendingto be legally bound, hereby agrees to amend the as follows:
     1.1. Definitions. Capitalized terms not otherwise defined in this Amendment shallhave the respective meanings ascribed to such terms in the .



     2.1. Recitals. The first recital of the Registration Rights Agreement is herebyamended by deleting the reference to “6% Series A Convertible Preferred Stock” therefrom andinserting in lieu thereof “6% Class A Convertible Preferred Stock”.
     2.2. Section 1. Section 1 of the Registration Rights Agreement is hereby amended bydeleting the definition of “Permitted Holder” therefrom in its entirety and inserting in lieuthereof the following:
     “Permitted Holder” means and includes: (i) a Purchaser or any Affiliate (asdefined in the Stock Purchase Agreement) of a Purchaser; (ii) any Person to whom aPurchaser or its transferee transfers its Convertible Preferred Stock and/or CommonStock, in whole or in part, together with the assignment of such Purchaser’s ortransferee’s (as applicable) rights under this Agreement under Section 6 hereof;(iii) any member of the Icahn Family; (iv) any conservatorship, custodianship, ordecedent’s estate of any member of the Icahn Family; (v) any trust established forthe benefit of, among others, any Person described in clause (iii) or (iv) of thisdefinition; (vi) any corporation, limited liability company, partnership, or otherentity, the controlling equity interests in which are held by or for the benefit ofany one or more Persons described in clause (iii), (iv), or (v) of this definition;and (vii) any foundation or charitable organization established by a member of theIcahn Family, and having at least one director, trustee, or member who is a memberof the Icahn Family.”
     2.3. Section 6. Section 6 of the Registration Rights Agreement is hereby amended bydeleting the last sentence thereof in its entirety and inserting in lieu thereof the following:
     “The Purchasers may, at their election, at any time or from time to time,assign their rights under this Agreement, in whole or in part, to any Affiliate orany purchaser or other transferee of shares of Convertible Preferred Stock and/orCommon Stock held by them.”
     3.1. Full Force and Effect. Except as expressly modified by this Amendment, all ofthe terms, covenants, agreements, conditions and other provisions of the Registration RightsAgreement shall remain in full force and effect in accordance with their respective terms. As usedin the Registration Rights Agreement, the terms “this Agreement,” herein, hereinafter, hereunder,hereto and words of similar import shall mean and refer to, from and after the date hereof, unlessthe context otherwise requires, the Registration Rights Agreement as amended by this Amendment.



     3.2. Governing Law. This Amendment shall be governed by and construed and enforced inaccordance with the laws of the State of New York, without regard to its conflict of laws rules orprinciples.
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     IN WITNESS WHEREOF, the undersigned has caused this Amendment No. 1 to RegistrationRights Agreement to be duly executed as of the date first written above.
  By:    /s/Carl J. Grivner  
    Name:   Carl J. Grivner   
    Title:   President and Chief Executive Officer