Sirius XM Radio posted a $4.8 billion net loss for the third quarter due to a big "impairment charge" related to a decline in its share price since the February 2007 agreement to merge the companies.

It has faced a tough economy and slow auto sales since consummating the merger; executives said this week it continues to work with creditors. It faces a debt payment of nearly $1 billion next year.

Excluding the impairment charge and assuming the merger had occurred at the beginning of the year, results show a loss of $217 million, compared to a loss of $265.5 million a year earlier, the company said.

For Q3, the company reported revenue of $613 million, up 16% over the year ago quarter. Sirius XM ended the quarter with 18.9 million subscribers, up 17% from the same period a year ago. During the third quarter, it added 344,100 net subscribers.

CEO Mel Karmazin said the latest numbers "demonstrate strong revenue growth, solid cost control and most importantly a clear path to positive cash flow ... In the first 60 days following the merger, Sirius XM is operationally very close to break-even."