XM Satellite Adds 617,000 Subscribers

XM Satellite Radio Holdings Inc., the biggest U.S. pay-radio service, added 617,000 subscribers in the third quarter, 48% more than it gained a year earlier, for a total of 5 million users.

Including the additions in the third quarter, 1.8 million subscribers have signed up this year, Washington-based XM said.

Sirius Satellite Radio Inc. has 2.1 million subscribers.