AGREEMENT

This AGREEMENT, dated as of January 28, 2003 (this "Agreement"), is entered into by and among XM Satellite Radio Holdings Inc., a corporation organized under the laws of the State of Delaware (the "Company"), and each of the note holders of the Company identified on the signature pages hereto (each, a "Note holder" and, collectively, the "Note holders"). Capitalized terms used herein and not otherwise defined have the meanings ascribed to them in the Note Purchase Agreement (as defined below).

WHEREAS, the Company, the Company's subsidiary, XM Satellite Radio Inc. ("XM"), each of the Note holders and certain other investors entered into a Note Purchase Agreement, dated as of December 21, 2002 (the "Note Purchase Agreement"), whereby the Note holders and certain other investors agreed to purchase the 10% Senior Secured Discount Convertible Notes due 2009 of the Company and XM (the "Notes");

WHEREAS, pursuant to the Note Purchase Agreement, upon issuance of the Notes, a holder of Notes may convert all or any portion of its Notes into shares of the Company's Class A common stock, par value $.01 per share (the "Class A Common Stock"), at a conversion price of$3.18 per share;

WHEREAS, the Company has reserved 40,000,000 of the 58,176,100 shares of Class A Common Stock for issuance upon conversion of the aggregate initial value of the Notes;

WHEREAS, the Company has agreed to seek stockholder approval to amend the Company's Restated Certificate of Incorporation to increase the number of authorized shares of Class A Common Stock to 600,000,000 in order to, among other things, enable the Company to reserve additional shares of Class A Common Stock to the extent is s u able from time to time upon conversion of the Notes (the "Charter Amendment"); and

WHEREAS, in order to facilitate the Concurrent Financing Transactions, the parties hereto desire that certain of the Notes not be converted until such stockholder approval has been obtained and the Charter Amendment has become effective.

NOW, THEREFORE, the parties hereto, in consideration of the foregoing, the mutual covenants and agreements contained herein and for other good and valuable consideration, the receipt and sufficiency of which hereby are acknowledged, and intending to be legally bound hereby, agree as follows:

SECTION 1. AGREEMENT NOT TO CONVERT

Each Note holder hereby agrees that it will not seek or attempt to convert the Notes held by it into Class A Common Stock until the sixty-first day following the earlier of: (i) the date of the next shareholder meeting of the Company and (ii) the date that is six months after the Closing Date.

SECTION 2. SPECIFIC PERFORMANCE

The parties agree that irreparable damage would occur in the event that any provision of this Agreement was, or is, not performed in accordance with its specific terms or was, or is, otherwise breached. Each Note holder agrees that, in the event of any breach or threatened breach by such Note holder of any covenant or obligation contained in this Agreement, the Company shall be entitled (in addition to any other remedy that may be available to it, including monetary damages) to (a) a decree or order of specific performance to enforce the observance and performance of such covenant or obligation, and (b) an injunction restraining such breach or threatened breach. Each Note holder further agrees that neither the Company nor any other person shall be required to obtain, furnish or post any bond or similar instrument in connection with or as a condition to obtaining any remedy referred to in this Section 2, and each Note holder irrevocably waives any objection to the imposition of such relief or any right he may have to require the obtaining, furnishing or posting of any such bond or similar instrument.

SECTION 3. ASSIGNMENT; BINDING EFFECT

This Agreement may not be assigned or delegated by a Note holder without the prior written consent of the Company, which consent shall not be unreasonably withheld. This Agreement shall be binding upon, and inure to the benefit of, the Note holders and their respective successors and assigns, and shall be binding upon, and inure to the benefit of, the Company and its successors and assigns; provided, however, that a transferee of a Note holder that is not an Affiliate of such Note holder shall not be subject to the provisions of Section 1 hereof with respect to the conversion of any Notes.

SECTION 4. AMENDMENT AND WAIVER

This Agreement shall not be amended, altered or modified except by an instrument in writing duly executed and delivered on behalf of each of the parties hereto that will be adversely affected thereby. No failure on the part of the Company to exercise any power, right, privilege or remedy under this Agreement, and no delay on the part of the Company in exercising any power, right, privilege or remedy under this Agreement, shall operate as a waiver of such power, right, privilege or remedy; and no single or partial exercise of any such power, right, privilege or remedy shall preclude any other or further exercise thereof or of any other power, right, privilege or remedy. The Company shall not be deemed to have waived any claim available to the Company arising out of this Agreement, or any power, right, privilege or remedy of the Company under this Agreement, unless the waiver of such claim, power, right, privilege or remedy is expressly set forth in a written instrument duly executed and delivered on behalf of the Company; and any such waiver shall not be applicable or have any effect except in the specific instance in which it is given.

SECTION 5. ENTIRE AGREEMENT

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