What else is stewing in our cauldron of evil? Prepare yourself before proceeding to the rest of our world's scariest stocks.

My worst Halloween fright-mare is that my broker automatically sells all my holdings in solid companies such as Berkshire Hathaway (NYSE:BRK-B), Markel (NYSE:MKL), and American Express (NYSE:AXP), and puts all the proceeds in one of the worst businesses I can imagine. It's a company that competes every day with free alternatives, has destroyed billions of dollars in shareholder capital, and as far as I can see, will continue to do so for years to come -- if it manages to avoid bankruptcy.

My scary stock is Sirius XM Radio (NASDAQ:SIRI), and as if to confirm my worst fears, the company recently announced that it will launch a Halloween Channel. Fortunately for those who don't want to be completely terrified, the channel will concentrate on scary sound effects, instead of recounting the company's ghoulish financial performance.

The fright-mare begins
So what's not to love about a company whose shares trade for only $0.60 a pop (as of Friday morning) and that, for some fluky speculators who bought back on Feb. 11, has been a 10-bagger? For starters, putting money into Sirius XM is simply gambling, not investing. And once you've bought the shares, you might stop to think about who's on the other side of the trade -- it could be someone with a lot more knowledge of the company's prospects. Like, say, CFO David J. Frear and four other executives, who have been selling furiously since they received a collective 10 million restricted shares in May. To me, that's plain freaky. If they thought the shares were undervalued, wouldn't they most likely hold?

So what's the value of the company? Capital IQ data tells me the market value is $0.58 for each of Sirius XM's 3.89 billion shares, for a market cap of $2.3 billion. But that's only half the story, since companies can source capital in many different ways. Don't forget that Sirius XM has some $3.3 billion in debt. Then there's Liberty Media Capital (NASDAQ:LCAPA), holding 1 million preference shares that can be converted into a dilutive 40% of the equity. Add all that together, and the implied enterprise value is around $7 billion. The balance sheet shows $144 million in shareholder equity, but even that figure is possible only because of past cash injections from share issuance.

Startled awake
I like the product Sirius XM offers, but like many others, I am unwilling to pay for services that I can get free elsewhere. On short journeys in my car, I am almost always most interested in local traffic conditions, and for longer journeys, I can take my own choice of music with me. In my house, I get HD radio with my satellite TV subscription. The company's Sky Dock may make its product more portable, but I question the demand for it -- and besides, it would seem to be at odds with fixed receivers that are already installed in automobiles, which are the company's current biggest customer.

Foolish final word
Since Day One, both Sirius and XM were classic examples of a quality product and an absolutely lousy investment. The current share price sounds really cheap, but it doesn't matter whether you have 10,000 shares in Sirius XM or 100 shares in a company with a $60 share price: Either way, you still have $6,000 on the line. If you choose to put that money in Sirius XM, just remember that you're speculating. You might have better luck splashing the cash into a Las Vegas Halloween party and using your leftover funds to play poker or blackjack.

Phew! I just checked my portfolio, and Berkshire's still there. Nary a SIRI in sight. What a scary dream!

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Fool contributor Philip Durell owns shares of American Express, Berkshire Hathaway, and Markel. Berkshire Hathaway is a Motley Fool Stock Advisor recommendation. American Express, Berkshire Hathaway, and Markel are Motley Fool Inside Value recommendations. The Fool owns shares of Berkshire Hathaway and Markel, and its disclosure policy isn't scared of ghouls or ghosts.