One of the great maxims of traders and Wall Street pros is to follow the "smart money."

I'm not much for the thesis that institutional shoppers tend to make smarter investing decisions, but many of you who've read my ruminations on insider buying say you'd also like to know how the Big Money is betting. Your wish is my command.

Next up: Sirius XM Radio (Nasdaq: SIRI). Are institutions bullish or bearish when it comes to the satellite radio pioneer?

Foolish facts

Metric

Sirius XM Radio

Motley Fool CAPS stars (out of 5) **
Total ratings 4,683
Percent bulls 80.2%
Percent bears 19.8%
Bullish pitches 995 out of 1,200
Highest rated peers Comcast, Dish Network, DirecTV

Data current as of Oct. 24.

Fools rating Sirius in Motley Fool CAPS give the stock only two of five stars, an indication they don't think of much of its chances to beat the market from here.

"Seriously, [what's with] all the recent thumbs up? Between $17 in debt for every dollar of equity, paltry earnings, and a good chance that smartphones will soon provide competition ... I don't see who would want this business without somehow retiring that debt," wrote All-Star investor wwheeling last week.

I'm less concerned about Sirius' debt than I used to be. Management's had no trouble refinancing hundreds of millions in obligations, and the stock trades for a historically reasonable 2.98 times revenue when compared to enterprise value.

Institutional ownership history

Top Owners

Latest*

2009*

2008*

2007*

MFC Global Investment

147,589,685

162,675,859

56,106,368

61,045

The Vanguard Group

141,292,404

153,951,809

85,525,638

38,606,558

BlackRock

121,807,972

59,417,116

3,317,588

5,400,188

Apollo Management

91,857,857

91,857,857

91,857,857

91,857,857

State Street Global Advisors

37,468,206

12,697,880

30,084,307

25,883,808

TOP 25 TOTAL

834,749,482

559,984,593

562,531,994

206,775,099

Source: Capital IQ, a division of Standard & Poor's.
*Indicates the number of shares owned.

Forget what I said about the smart money not being smart. Big-money institutions have loaded up on shares of Sirius over the past three years, with buying accelerating in the last year. Many have since more than doubled their money.

Competitor and peer checkup

Company

Institutional Ownership

Insider Ownership

Apple (Nasdaq: AAPL) 66.47% 0.72%
CBS (NYSE: CBS) 84.67% 0.37%
Entravision Communications (NYSE: EVC) 42.97% 21.70%
Motorola (NYSE: MOT) 65.10% 0.19%
Sirius XM Radio 18.87% 0.52%
Time Warner (NYSE: TWX) 81.00% 0.06%

Source: Capital IQ. Data current as of Oct. 20.

Sirius XM fits the industry average when it comes to insider ownership. And CEO Mel Karmazin still holds 8.8 million shares.

But it's institutional ownership where this stock story gets most interesting. The Big Money may be buying, but with less than 20% of the outstanding shares, they've yet to fully commit to Sirius XM Radio. The stock should rally nicely when they do. As such, I'm calling for it to outperform in my CAPS portfolio.

Now it's your turn to weigh in. Do you think now's the time to buy Sirius XM? Let the debate begin in the comments box below. You can also recommended other stocks for Tim to evaluate by sending him an email, or replying to him on Twitter.

For further Foolishness featuring Sirius XM Radio:

Interested in more info on Sirius XM Radio? Add it to your watchlist here by clicking here.

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Fool contributor Tim Beyers is a member of the Motley Fool Rule Breakers stock-picking team. He didn't own shares in any of the companies mentioned in this article at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Twitter as @milehighfool. You can also get his insights delivered directly to your RSS reader. The Motley Fool owns shares of Apple and Google and is also on Twitter as @TheMotleyFool. Its disclosure policy is smarter than the average bear.