One of the great things about The Motley Fool is that all writers must disclose their positions (if any) in the companies they write about.  At The Motley Fool, you know exactly whether writers are short or long the stocks they're covering. And with that as preamble, I have a short put option position in Sirius XM Radio (Nasdaq: SIRI). But you probably guessed that. 

Sirius' stock has performed admirably in the past few years, after John Malone and the Liberty empire came to town to rationalize the company's operations. That's resulted in significant cash flow, operating profit, and even a net profit in five of the past six quarters. But the past doesn't predict the future, and with significant trends playing against the company, I think the future will be rougher. I'll look at three reasons I'm short the satellite-radio provider.

1. Increasing competition from larger and better players
Sirius has a subscription-based product that many love, but there are many other and better alternatives around. Take Pandora Media (NYSE: P), which provides free tunes from a massive catalog and helps users discover new music based on their preferences. OK, the free music requires you to listen to ads, but you choose the music you want to hear. Pandora already has a mobile app for Apple (Nasdaq: AAPL) products and Google's (Nasdaq: GOOG) Android platform, meaning the music travels wherever you go. And now Spotify is a competitor on this side of the Atlantic, too. In short, the field is only getting more crowded.

But Pandora and Spotify are really just upstarts, compared with the massive moves that Apple and Google are making into the cloud. Oh, and then there's also (Nasdaq: AMZN) angling for a piece of the pie. And Amazon is the "small" player of these three giants, with a market cap of just $100 billion. These companies are making your music available anywhere you have a Web connection. With tech's megacaps having a laser focus on music, I'm not sure where the $8.5 billion Sirius fits in.

2. The trend isn't Sirius' friend
The whole consumerist movement of the past century has been trending toward doing what you want, when you want. So why pay Sirius to program music and then have to listen to songs or other programming that you don't want to hear? Again, it seems the megacaps are positioning themselves to capture that trend, while Sirius is still stuck in the old-media paradigm of programming. Let listeners do the programming.

3. High short interest
As of June 30, Sirius has the highest short interest of any stock on the Nasdaq exchange, with 271 million shares short. That was down slightly from 292 million shares two weeks earlier. Now, it's not entirely fair to look at short shares in isolation; the percentage of the total share count is a more relevant metric. On that count, Sirius has 3.94 billion shares outstanding, so that 271 million figure translates into nearly 7% of shares being short.

While 7% isn't an egregiously high figure, it does suggest that some investors have taken a fairly substantial short position, and that indicates that I'm not the only one who thinks Sirius might run into some troubles. That figure has plenty of room to grow, should Sirius misstep.

Foolish bottom line
Sirius the stock has performed well, but with competitive threats quickly lining up, where does the company go from here?

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.