305,437 subscribers added during quarter.

Sirius Satellite Radio Inc. on Thursday posted a loss of $193.6 million in the first quarter, compared with a loss of $144.1 million a year ago despite revenue that more than quadrupled to $43.2 million as its cost to acquire subscribers rose.

While the loss disappointed some analysts who weren't expecting so substantial a drain, Sirius impressed them by adding 305,437 subscribers during the quarter, up from 90,602 a year ago. That brought its total subscriber base to 1.5 million as of the end of last month and allowed it to increase its full-year user growth target.

“Let me assure you that we are totally focused on all of our costs," Sirius CEO Mel Karmazin told analysts. "There is nothing more important to me than making this company not just profitable but a very profitable company."

Sirius said that subscriber acquisition costs were at $190 for the quarter and should decline to $145 for the full year, better than Banc of America analyst Jonathan Jacoby expected. A day earlier, XM reported that its SAC is $52.

Sirius now expects to end the year with 2.7 million subscribers, up from its previous estimate of 2.5 million, while rival XM Satellite Radio on Wednesday stuck to its previous guidance of ending the year with 5.5 million subscribers despite strong first-quarter gains.

Jacoby expressed concern in a note Thursday that Sirius captured 35% of new satellite radio subscribers with the rest going to XM. He had expected Sirius' share to be closer to 37%.

While the tech-heavy Nasdaq lost points, and XM shares took a 3.7% drubbing to $27.30, Sirius gained 1.5% to close at $4.74.