Task: Question Generation
Input (English): Context : On July 29, 2008, XM and former competitor Sirius Satellite Radio formally completed their merger, following U.S. Federal Communications Commission (FCC) approval, forming Sirius XM Radio, Inc. with XM Satellite Radio, Inc. as its subsidiary. 
Subject : XM Satellite Radio 
Relation : parent company
Output (English): What is XM Satellite Radio's parent company?