Sirius XM Radio (SIRI)

Registrant’s telephone number, including area code: (212) 584-5100

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  ¨    No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).    Yes  ¨    No  x

Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

SIRIUS XM RADIO INC. AND SUBSIDIARIES

Registrant’s telephone number, including area code: (212) 584-5100

Registrant’s telephone number, including area code: (212) 584-5100

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

In connection with a Form S-3 registration statement that Sirius XM Radio Inc. (the “Company”) intends to file today, the Company is providing unaudited pro forma condensed combined statements of operations and accompanying notes for the nine months ended September 30, 2008 and for the fiscal year ended December 31, 2007 relating to its merger with XM Satellite Radio Holdings Inc. (“XM”). This pro forma financial information is attached as Exhibit 99.1 to this report and incorporated by reference herein.

In accordance with Rule 11–02(c)(1) of Regulation S–X of the Securities Exchange Act of 1934, as amended, a pro forma balance sheet has not been prepared to give effect to the merger with XM as of September 30, 2008, as it is reflected in the consolidated balance sheet presented in the quarterly report filed on Form 10–Q for the period ended September 30, 2008.

(a) Not Applicable.

(b) Not Applicable.

(c) Not Applicable.

(d) Exhibits.

The Exhibit Index attached hereto is incorporated herein.