I do not know for certain, but the Federal Communications Commission seems to be the most active of the federal regulatory commissions. A rank ordering of these commissions, in terms of activities, would be helpful.
Here is information about recent activity concerning its impending decision about whether to allow a merger between Sirius and XM Radio to go forward. Some allege that this will create a monopoly, while others point out that other technological advances, some driven by Apple, make a long term monopoly unlikely.
The post is from C-Net. Here is a link to its past postings on the FCC.
Just curious: Why doesn't the Federal Trade Commission have jurisdiction over this?