Interestingly enough, at least in the 'news to me' category, Sirius and XM count their subscriber numbers differently from each other. I was never aware of this, but I'm sure a bunch of you stock/investor geeks have been all over this already. For the rest of us who can barely spell "CFBE" it's sort of eye opening.

Apparently Legg Mason analyst Sean Butson was speculating that XM Satellite Radio has hit 5 Million subscribers this past weekend - basing his figures on "recent auto and retail trends." In his report, he said something verrrry curious that was also echo'd in last Wednesday's BoA Investment Conference.

Shall I quote?

Based on recent auto and retail trends, we believe XM is on pace to cross the 5M subscriber mark this weekend.

If the company counted subscribers when the car is delivered to the dealer (similar to Sirius) instead of when the car is sold, we believe XM would have nearly 5.5M subscribers due to the 400,000-500,000 XM-installed autos sitting on lots.

Importantly, if XM did adjust its subscriber count to match its competitor, this would reduce ARPU by about 7%-9% due to the fact that despite different subscriber recognition, Sirius and XM both recognize auto revenue when the car is sold. Churn would decline by a similar percentage.

So wait. Sirius counts a subscription when it's delivered to the dealership (essentially "sold" to the dealer), whereas XM counts a subscription when it's... activated (after the "trial" period?!). If you anyone has more info to add to this, I'd really be interested. It's hard to compare the subscriber numbers between the two when there's no standard for measurement.