Howard Stern is returning to Sirius XM Radio Inc, the shock jock reported on his website on Thursday, sending shares of the satellite radio company up 8 percent. posted a message saying Howard announced this morning that he has signed a new 5 year deal with SiriusXM Radio, and that more details were to follow.

Radio shock-jock Stern's previous five-year, $500 million contract with Sirius XM Radio expires in December and investors have expressed concern that subscribers would abandon the service if Stern were to move on.

One estimate says Stern brought 1.2 million subscribers aboard when he joined the service.

Shares were up 10.5 cents, or 8 percent, at $1.42 in heavy premarket trading.

(Reporting by Liana Baker; Editing by Derek Caney)