Every time we mention Sirius XM Satellite Radio (NASDAQ:SIRI) here at the Fool, its shareholders seem to take that as a personal attack. Last week, fellow Fool Rick Munarriz even took the time to explain what he did and didn't like about the satellite radio operator -- and got drowned in a flood of fervent protests.

Well, Sirius XM looks risky to me, thanks to mounting losses on top of a shaky balance sheet. Satellite radio is a very cool technology with real benefits for its customers. But launching satellites is also a very expensive way to run a business, and the TV satellite companies overcome that hurdle by charging subscription fees no radio package could ever rival. Cool tech does not always translate to real profits, or else we'd all be slinging Iridium phones today. But Iridium turned out to be a massive waste of money in the end -- and Sirius could very well go the same way.

Where's the beef?
Nonetheless, do these borderline fanatical Sirius XM defenders have a point? Well, the stock has quadrupled in the past six months, which gives them a decent platform from which they can sling some mud. Of course, Sirius fans aren’t alone in that department:

Company

Current Market Cap (in Billions)

6-Month Return

CAPS Rating (out of 5 stars)

Las Vegas Sands (NYSE:LVS)

$11.1

1,088%

**

Genworth Financial (NYSE:GNW)

$4.5

1,031%

***

Dendreon (NASDAQ:DNDN)

$2.8

808%

**

Barclays (NYSE:BCS)

$67.3

632%

***

Allied Irish Banks (NYSE:AIB)

$2.9

620%

****

Brookdale Senior Living (NYSE:BKD)

$2.0

418%

***

Sirius XM

$3.9

364%

**

Market data from Google Finance.

All of these stocks have rewarded shareholders handsomely, assuming they timed their purchases perfectly and bought in six months ago. They range from global megabank Barclays (and a lot of smaller banks) to biotech outfit Dendreon to troubled casino Las Vegas Sands. Most of them also have very vocal supporters, though none quite as rabid as the Sirians.

What are you saying, Fool?
It seems obvious to me that a short period of market-beating stock returns does not make for a reliable investment thesis. Dendreon has popped on positive FDA approval news before -- and then crashed hard on the next batch of bad news. Is Barclays too big to fail? Well, we thought the same of Lehman Brothers and Enron back in the day.

In the long run, fundamentals drive price movements. All of these superball bounces are examples of companies that squeaked by in the market meltdown -- but buy-and-forget tactics using these stocks would be certifiably insane in my opinion. This includes Sirius XM.

Go ahead, flame away in the comments section. This asbestos suit has been battle-tested before.

Allied Irish Banks is a Motley Fool Global Gains recommendation. The Fool owns shares of Allied Irish Banks. Try any of our Foolish newsletters today, free for 30 days.

Fool contributor Anders Bylund holds no position in any of the companies discussed here. You can check out Anders' holdings or a concise bio if you like, and The Motley Fool is investors writing for investors.