XM Satellite Radio Holdings, the larger of the US’s two satellite radio broadcasters, posted a wider loss in the third quarter due to higher programming and marketing costs even as revenue rose and subscribers more than doubled from a year ago.

The Associated Press (AP) said the company had a net loss of US$134m, or 60 cents per share, compared with $120.1m, or 59 cents per share, the year before. Analysts surveyed by Thomson Financial expected a loss of 66 cents per share.

One piece of news troubling investors was another decline in the “conversion” rate at XM’s key promotional programme with General Motors, or the portion of customers who elect to sign up after an initial trial period. That rate fell to 56% in the quarter, from 58% in the previous quarter and 60% a year ago, AP noted.

Sanford C Bernstein analyst Craig Moffett reportedly called the continued decline in the conversion rate a “disappointment” in a note to investors, and said it boded poorly for prospects for other pre-install programmes for XM radios at other car makers since GM is the first and largest car company to carry the radios.

“The rate of decline is somewhat steeper than we expected or would have liked to see,” Moffett wrote, according to AP.

The Associated Press added that investors may also have been concerned about an announcement on Wednesday (26 October) from GM, which said it plans to build 1.55m vehicles next year with factory-installed XM radios, up only 11% from 1.4m in 2005. This year’s figure represents growth of about 20% from the 1.17m installed in GM cars in 2004.