SiriusXM Radio saw profit jump last quarter on revenue up 6 percent to $763 million.The satellite radio giant said net income grew to $104 million from $68 million. It added 334,000 net new subscribers over the period to finish with 21.3 million subscribers. Investors may have expected faster overall sub growth and tad higher revenue, sending Sirius stock lower in pre-market trade. It was off by more than 7 percent before the bell. Sirius’s subscriber acquisition costs were also down. Its cash position solid with $600 million on hand at the end of the quarter. Sirius attributed the uptick in gross subscribers to an increase in U.S. light vehicle sales, new vehicle penetration and returning activations. SiriusXM installation deals with automakers are a key to its business. It expects another revenue bump — up 10 percent to $4.4 billion — for 2012 when it raises the price of its core SiriusXM package by $1.50 a year to $12.29. Average monthly churn was steady at 1.9 percent. ”This has been an exciting year for SiriusXM, but I’m even more excited by the many opportunities awaiting us in 2012,” CEO Mel Karmazin said in a statement.