<PAGE>

                                                                    Exhibit 10.1

                               PURCHASE AGREEMENT

              This purchase agreement (this "Agreement"), dated as of September
5, 2003, is between T. ROWE PRICE ASSOCIATES, INC. (the "Purchaser") and XM
Satellite Radio Holdings Inc. (the "Seller").

              WHEREAS, the Purchaser, on behalf of certain of its clients over
whose accounts the Purchaser has investment discretion (each such client a
"Participating Client"), desires to purchase from Seller, and Seller desires to
issue and sell to Purchaser, 4,000,000 shares of its common stock, par value
$0.01 per share (the "Shares").

              NOW, THEREFORE, in consideration of the mutual promises herein
contained, the parties hereto agree as follows:

              1.     Purchase and Sale. Subject to the terms and conditions
hereof, the Purchaser hereby agrees to purchase from Seller, and Seller agrees
to issue and to sell to Purchaser, the Shares at a price per share of $13.25 for
an aggregate purchase amount of Fifty Three Million Dollars ($53,000,000) (the
"Purchase Price").

              2.     Representations and Warranties of Purchaser. The Purchaser
represents and warrants that:

              (a)    Due Authorization. The Purchaser is duly authorized to
       purchase the Shares on behalf of each Participating Client. This
       Agreement has been duly authorized, executed and delivered by the
       Purchaser and constitutes a legal, valid and binding agreement of the
       Purchaser, enforceable against the Purchaser in accordance with its terms
       except as may be limited by (i) the effect of bankruptcy, insolvency,
       reorganization, moratorium or other similar laws relating to or affecting
       the rights or remedies of creditors, (ii) the effect of general
       principles of equity, whether enforcement is considered in a proceeding
       in equity or at law and the discretion of the court before which any
       proceeding therefore may be brought and a requirement that an effective
       prospectus be delivered prior to closing.

              3.     Representations and Warranties of Seller. Seller
represents, warrants and agrees that:

              (a)    Due Authorization. This Agreement has been duly authorized,
       executed and delivered by Seller and constitutes a legal, valid and
       binding agreement of Seller, enforceable against Seller in accordance
       with its terms except as may be limited by (i) the effect of bankruptcy,
       insolvency, reorganization, moratorium or other similar laws relating to
       or affecting the rights or remedies of creditors or (ii) the effect of
       general principles of equity, whether enforcement is considered in a
       proceeding in equity or at law and the discretion of the court before
       which any proceeding therefore may be brought. No approvals or other
       authorizations are required in connection with the Agreement and the
       issuance of the Shares, other than approvals which have been obtained.

<PAGE>

              (b)    Organization and Authority. Seller has been duly organized
       and is validly existing in good standing under the laws of the State of
       Delaware, with full power and authority to own or lease and occupy its
       properties and conduct its business as described in the Prospectus
       (including the documents incorporated therein by reference).

              (c)    Issuance of the Shares. The Shares have been duly and
       validly authorized, and, when issued and delivered pursuant to this
       Agreement, will be fully paid and nonassessable, free of restrictions
       upon transferability under federal and state securities laws, and will be
       listed, subject to notice of issuance, on the Nasdaq National Market
       effective as of the Closing (as defined in Paragraph 5 of this
       Agreement).

              (d)    Absence of Conflicts. The execution, delivery and
       performance of this Agreement and the consummation of the transactions
       contemplated herein do not and will not result in the creation or
       imposition of any lien, charge or encumbrance upon any property or assets
       of the Seller.

              (e)    Effective Registration Statement. There is an effective
       registration statement (File No. 333-89132) filed under the Securities
       Act of 1933 relating to the Shares and seller will deliver a prospectus
       prior to closing and such documents will be filed with the Securities and
       Exchange Commission as required under federal securities laws.

              4.     Conditions to Obligations of the Parties. The obligations
of the parties hereto to effect the transactions contemplated by this Agreement
shall be subject to each of the representations and warranties of the parties
hereto, which shall be true and correct in all respects.

              5.     Closing. The transactions contemplated hereby shall be
consummated on Wednesday, September 10, 2003 (such time and date of payment and
delivery being herein called the "Closing") and the Shares will be issued in
electronic book entry form on a delivery versus payment basis via the DTC DWAC
System.

              6.     Governing Law. This Agreement shall be construed in
accordance with and governed by the substantive laws of the State of New York.

              7.     Entire Agreement. This Agreement constitutes the entire
agreement between the parties hereto with respect to the subject matter hereof
and may be amended only in a writing that is executed by each of the parties
hereto.

              8.     Counterparts. This Agreement may be executed in separate
counterparts, each of which shall be deemed an original, and all of which
together shall be deemed to constitute one and the same instrument.

<PAGE>

       IN WITNESS WHEREOF, the parties hereto have executed and delivered this
Agreement as of the date first set forth above.


                                   XM SATELLITE RADIO HOLDINGS INC.

                                   By: /s/ Joseph M. Titlebaum
                                      ----------------------------------------

                                   Name:   Joseph M. Titlebaum
                                   Title:  Executive Vice President, General
                                             Counsel and Secretary



                                   T. ROWE PRICE ASSOCIATES, INC., on behalf
                                   of the Participating Clients



                                   By: /s/ Andrew M. Brooks
                                      ----------------------------------------
                                   Name:   Andrew M. Brooks
                                   Title:  Vice President

<PAGE>

                               PURCHASE AGREEMENT

              This purchase agreement (this "Agreement"), dated as of September
5, 2003, is between Legg Mason Capital Management, Inc. (the "Purchaser") and XM
Satellite Radio Holdings Inc. (the "Seller").

              WHEREAS, the Purchaser, on behalf of certain of its clients over
whose accounts the Purchaser has investment discretion (each such client a
"Participating Client"), desires to purchase from Seller, and Seller desires to
issue and sell to Purchaser, 355,000 shares of its common stock, par value $0.01
per share (the "Shares").

              NOW, THEREFORE, in consideration of the mutual promises herein
contained, the parties hereto agree as follows:

              1.     Purchase and Sale. Subject to the terms and conditions
hereof, the Purchaser hereby agrees to purchase from Seller, and Seller agrees
to issue and to sell to Purchaser, the Shares at a price per share of $13.25 for
an aggregate purchase amount of four million seven hundred three thousand seven
hundred fifty dollars ($4,703,750) (the "Purchase Price").

              2.     Representations and Warranties of Purchaser. The Purchaser
represents and warrants that:

              (a)    Due Authorization. The Purchaser is duly authorized to
       purchase the Shares on behalf of each Participating Client. This
       Agreement has been duly authorized, executed and delivered by the
       Purchaser and constitutes a legal, valid and binding agreement of the
       Purchaser, enforceable against the Purchaser in accordance with its terms
       except as may be limited by (i) the effect of bankruptcy, insolvency,
       reorganization, moratorium or other similar laws relating to or affecting
       the rights or remedies of creditors, (ii) the effect of general
       principles of equity, whether enforcement is considered in a proceeding
       in equity or at law and the discretion of the court before which any
       proceeding therefore may be brought and a requirement that an effective
       prospectus be delivered prior to closing.

              3.     Representations and Warranties of Seller. Seller
represents, warrants and agrees that:

              (a)    Due Authorization. This Agreement has been duly authorized,
       executed and delivered by Seller and constitutes a legal, valid and
       binding agreement of Seller, enforceable against Seller in accordance
       with its terms except as may be limited by (i) the effect of bankruptcy,
       insolvency, reorganization, moratorium or other similar laws relating to
       or affecting the rights or remedies of creditors or (ii) the effect of
       general principles of equity, whether enforcement is considered in a
       proceeding in equity or at law and the discretion of the court before
       which any proceeding therefore may be brought. No approvals or other
       authorizations are required in connection with the Agreement and the
       issuance of the Shares, other than approvals which have been obtained.

<PAGE>

              (b)    Organization and Authority. Seller has been duly organized
       and is validly existing in good standing under the laws of the State of
       Delaware, with full power and authority to own or lease and occupy its
       properties and conduct its business as described in the Prospectus
       (including the documents incorporated therein by reference).

              (c)    Issuance of the Shares. The Shares have been duly and
       validly authorized, and, when issued and delivered pursuant to this
       Agreement, will be fully paid and nonassessable free of restrictions upon
       transferability under federal and state securities laws, and will be
       listed, subject to notice of issuance, on the Nasdaq National Market
       effective as of the Closing (as defined in Paragraph 5 of this
       Agreement).

              (d)    Absence of Conflicts. The execution, delivery and
       performance of this Agreement and the consummation of the transactions
       contemplated herein do not and will not result in the creation or
       imposition of any lien, charge or encumbrance upon any property or assets
       of the Seller.

              (e)    Effective Registration Statement. There is an effective
       registration statement (File No. 333-89132) filed under the Securities
       Act of 1933 relating to the Shares and seller will deliver a prospectus
       prior to closing and such documents will be filed with the Securities and
       Exchange Commission as required under federal securities laws.

              4.     Conditions to Obligations of the Parties. The obligations
of the parties hereto to effect the transactions contemplated by this Agreement
shall be subject to each of the representations and warranties of the parties
hereto, which shall be true and correct in all respects.

              5.     Closing. The transactions contemplated hereby shall be
consummated on Wednesday, September 10, 2003 (such time and date of payment and
delivery being herein called the "Closing") and the Shares will be issued in
electronic book entry form on a delivery versus payment basis via the DTC DWAC
System.

              6.     Governing Law. This Agreement shall be construed in
accordance with and governed by the substantive laws of the State of New York.

              7.     Entire Agreement. This Agreement constitutes the entire
agreement between the parties hereto with respect to the subject matter hereof
and may be amended only in a writing that is executed by each of the parties
hereto.

              8.     Counterparts. This Agreement may be executed in separate
counterparts, each of which shall be deemed an original, and all of which
together shall be deemed to constitute one and the same instrument.

       IN WITNESS WHEREOF, the parties hereto have executed and delivered this
Agreement as of the date first set forth above.


                                   XM SATELLITE RADIO HOLDINGS INC.

<PAGE>

                                   By: /s/ Joseph M. Titlebaum
                                      ----------------------------------------

                                   Name: Joseph M. Titlebaum

                                   Title: Executive Vice President,
                                          General Counsel and Secretary


                                   By: /s/ Andrew J. Bowden
                                      ------------------------------------

                                   Name: Andrew J. Bowden

                                   Title: Senior VP and COO

                                   Company: Legg Mason Funds Management, Inc.
                                            ---------------------------------

<PAGE>

                               PURCHASE AGREEMENT

                  This purchase agreement (this "Agreement"), dated as of
September 5, 2003, is between Legg Mason Funds Management, Inc. (the
"Purchaser") and XM Satellite Radio Holdings Inc. (the "Seller").

                  WHEREAS, the Purchaser, on behalf of certain of its clients
over whose accounts the Purchaser has investment discretion (each such client a
"Participating Client"), desires to purchase from Seller, and Seller desires to
issue and sell to Purchaser, 6,965,755 shares of its common stock, par value
$0.01 per share (the "Shares").

                  NOW, THEREFORE, in consideration of the mutual promises herein
contained, the parties hereto agree as follows:

                  1.  Purchase and Sale. Subject to the terms and conditions
hereof, the Purchaser hereby agrees to purchase from Seller, and Seller agrees
to issue and to sell to Purchaser, the Shares at a price per share of $13.25 for
an aggregate purchase amount of ninety two million, two hundred ninety six
thousand eight hundred fifty dollars ($92,296,250) (the "Purchase Price").

                  2.  Representations and Warranties of Purchaser. The Purchaser
represents and warrants that:

                  (a) Due Authorization. The Purchaser is duly authorized to
         purchase the Shares on behalf of each Participating Client. This
         Agreement has been duly authorized, executed and delivered by the
         Purchaser and constitutes a legal, valid and binding agreement of the
         Purchaser, enforceable against the Purchaser in accordance with its
         terms except as may be limited by (i) the effect of bankruptcy,
         insolvency, reorganization, moratorium or other similar laws relating
         to or affecting the rights or remedies of creditors, (ii) the effect of
         general principles of equity, whether enforcement is considered in a
         proceeding in equity or at law and the discretion of the court before
         which any proceeding therefore may be brought and a requirement that an
         effective prospectus be delivered prior to closing.

                  3.  Representations and Warranties of Seller. Seller
represents, warrants and agrees that:

                  (a) Due Authorization. This Agreement has been duly
         authorized, executed and delivered by Seller and constitutes a legal,
         valid and binding agreement of Seller, enforceable against Seller in
         accordance with its terms except as may be limited by (i) the effect of
         bankruptcy, insolvency, reorganization, moratorium or other similar
         laws relating to or affecting the rights or remedies of creditors or
         (ii) the effect of general principles of equity, whether enforcement is
         considered in a proceeding in equity or at law and the discretion of
         the court before which any proceeding therefore may be brought. No
         approvals or other authorizations are required in connection with the
         Agreement and the issuance of the Shares, other than approvals which
         have been obtained.

<PAGE>

                  (b) Organization and Authority. Seller has been duly organized
         and is validly existing in good standing under the laws of the State of
         Delaware, with full power and authority to own or lease and occupy its
         properties and conduct its business as described in the Prospectus
         (including the documents incorporated therein by reference).

                  (c) Issuance of the Shares. The Shares have been duly and
         validly authorized, and, when issued and delivered pursuant to this
         Agreement, will be fully paid and nonassessable, free of restrictions
         upon transferability under federal and state securities laws, and will
         be listed, subject to notice of issuance, on the Nasdaq National Market
         effective as of the Closing (as defined in Paragraph 5 of this
         Agreement).

                  (d) Absence of Conflicts. The execution, delivery and
         performance of this Agreement and the consummation of the transactions
         contemplated herein do not and will not result in the creation or
         imposition of any lien, charge or encumbrance upon any property or
         assets of the Seller.

                  (e) Effective Registration Statement. There is an effective
         registration statement (File No. 333-89132) filed under the Securities
         Act of 1933 relating to the Shares and seller will deliver a prospectus
         prior to closing and such documents will be filed with the Securities
         and Exchange Commission as required under federal securities laws.

                  4.  Conditions to Obligations of the Parties. The obligations
of the parties hereto to effect the transactions contemplated by this Agreement
shall be subject to each of the representations and warranties of the parties
hereto, which shall be true and correct in all respects.

                  5.  Closing. The transactions contemplated hereby shall be
consummated on Wednesday, September 10, 2003 (such time and date of payment and
delivery being herein called the "Closing") and the Shares will be issued in
electronic book entry form on a delivery versus payment basis via the DTC DWAC
System.

                  6.  Governing Law. This Agreement shall be construed in
accordance with and governed by the substantive laws of the State of New York.

                  7.  Entire Agreement. This Agreement constitutes the entire
agreement between the parties hereto with respect to the subject matter hereof
and may be amended only in a writing that is executed by each of the parties
hereto.

         8.           Counterparts. This Agreement may be executed in separate
counterparts, each of which shall be deemed an original, and all of which
together shall be deemed to constitute one and the same instrument.

         IN WITNESS WHEREOF, the parties hereto have executed and delivered this
Agreement as of the date first set forth above.

                                             XM SATELLITE RADIO HOLDINGS INC.

<PAGE>

                                   By: /s/ Joseph M. Titlebaum
                                      ------------------------------------

                                   Name: Joseph M. Titlebaum

                                   Title: Executive Vice President,
                                          General Councel and Secretary

                                   By: /s/ William H. Miller, III
                                      ----------------------------------------

                                   Name: William H. Miller, III

                                   Title: CEO

                                   Company: Legg Mason Capital Management, Inc.