Sirius Satellite Radio now expects to finish 2006 with 6.3 million subscribers after adding more than 600,000 in the second quarter, the company announced Aug. 1. The company previously forecast that it would reach 6.2 million subscribers by the end of the year.

Sirius closed the second quarter, which ended June 30, with 4.7 million subscribers, a 158 percent gain from the 1.8 million subscribers the company reported at the end of the 2005 second quarter. This was the third straight quarter that Sirius led rival XM Satellite Radio in net subscriber additions.

The subscriber gains helped the satellite radio provider post revenues of $150.1 million in the 2006 second quarter, more than triple revenues of $52.2 in the 2005 second quarter. Subscriber revenues accounted for $88 million of the $97.9 million gain in total revenues. Average monthly revenue per subscriber was $11.16 in the second quarter of 2006, up from $10.50 a year ago.

Sirius raised its estimate for 2006 revenues to $615 million, up from the previous estimate of $600 million.

“Continued strong demand for Sirius’ products and programming gives us confidence to increase our revenue and subscriber guidance,” Mel Karmazin, the company’s CEO, said in a statement. “We continue to be excited about the growth prospects for satellite radio and remain pleased with our solid execution as we approach positive free cash flow.”

The growth in subscribers and revenues did not help Sirius cut its net loss, which reached $237.8 million in the 2006 second quarter. In the same period in 2005, the company lost $177.5 million. Total operating expenses jumped from $226.8 million to $380.6 million over the same period.

Subscriber acquisition cost per gross subscriber addition was $131 for the second quarter of 2006, down from $160 in the 2005 second quarter.