Well the FCC may let it go through as its not truly a monopolization of the market. When the FCC authorized satellite radio, it specifically found that the public would be served best by two competitive nationwide systems, however, both of those companies are losing money so there's a chance. Plus, satellite radio companies compete with broadcast radio and internet radio as well.
For the FCC to say that this would be a monopoly is like saying that Hasbro is a monopoly because they're the only company that makes GI Joe figures. You can't ignore the rest of the market. However, the DirecTV/Echostar (Dish) merger was blocked because it would create a monopoly in areas where there is no terrestrial signal, and this could probably be applied to satellite radio as well, so who knows.
What will happen to your stock is a good question. XM has more subscribers but Sirius' value is higher, and by the end of 2006, Sirius was gaining more subscribers at a pretty rapid rate, probably due to such strong Christmas promotions. Having Opie & Anthony and Stern on the same service would be pretty huge (personally I don't listen to either).
Here's a blurb from the AP:
QUOTE
C-MI--XM Radio-Sirius-Summary Box/192
Eds: Moving on general news, financial and entertainment services.
Key facts, figures in the XM-Sirius deal
By The Associated Press
XM SATELLITE RADIO HOLDINGS INC.
Headquarters: Washington, D.C.
Year-end subscriber count: 7.63 million
Executives: Chairman Gary Parsons will keep that role in newly combined company; CEO Hugh Panero will depart.
SIRIUS SATELLITE RADIO INC.
Headquarters: New York
Year-end subscriber count: Over 6 million.
Executives: CEO Mel Karmazin will lead the new company.
NEW COMPANY
Headquarters and name of new company are both undecided.
Combined 2006 revenues: About $1.5 billion.
Board of Directors: Will be made up of 12 people _ Parsons, Karmazin, four independent directors to be named by each company, and one director each will be named by General Motors Corp. and Honda Motor Co.
Ownership: Shareholders of Sirius and XM will each own about 50 percent of the new company.
WHAT'S NEXT: The deal must be approved by the Federal Communications Commission, which currently has a provision barring the two companies from merging. However, that rule could be change. Antitrust approval is also necessary.
There is something in the near future that will make all of this a moot point though. As public radio continues its slowly but surely imminent death, and satellite radio is holding steady, wi-fi (which will soon be wi-max) will be available via cell towers and Internet radio will be available via the airwaves via multicasting. At which point, all hell breaks loose and the FCC goes down in flames.