Sirius Satellite Radio plans to buy U.S. rival XM Satellite Radio for $4.6 billion in stock, which could allow the combined company to raise prices, reduce costs and become profitable. The move will bring Oprah Winfrey, singer Bob Dylan, Major League Baseball, motivational guru Deepak Chopra and shock-jock Howard Stern under one roof.

Under the plan announced by the companies Monday, XM shareholders would receive 4.6 Sirius shares for each XM share held, or a 21.7 percent premium based on the two companies’ Friday closing prices.

The deal may face a tough time winning approval, though, since it will create a satellite radio monopoly. U.S. Federal Communications Commission Chairman Kevin Martin said the agency would review the deal but the hurdle “would be high as the commission originally prohibited one company from holding the only two satellite radio licenses.”

Martin said the companies would have “to demonstrate that consumers would clearly be better off with both more choice and affordable prices.”

XM and Sirius argue they should be allowed to combine as they compete with every audio device that consumers use. Satellite radio has struggled to become profitable, faced with high subscriber-acquisition costs and growing competition from Internet radio and podcasting.

“We are confident we will get this through the regulatory arena by the end of this year,” said XM Chairman Gary Parsons. “Over a decade ago when the first satellite licenses first came out, there were no iPods, there was no HD radio, there were no streaming music on cell phones.”