XM Satellite Radio ( XMSR) posted another big quarterly loss but reaffirmed its year-end subscriber guidance. The Washington, D.C., pay-radio shop lost $132 million, or 60 cents a share, for the quarter ended Sept. 30, compared with the year-ago loss of $118 million, or 59 cents a share. Revenue rose to $153 million from the year-ago $65 million. Analysts surveyed by Thomson First Call had forecast a 68-cent loss on sales of $148 million. Subscribers doubled to 5,034,642 from the prior year, as the company counted 617,152 net additions. XM said it would end 2005 with 6 million users. Subscriber acquisition costs, reflecting the amount XM pays to attract each new user, fell to $53 from $57 a year earlier, while cost per gross add was flat at $89.