Shares of Sony (NYSE: SNE) are flying 3% higher today, and inquiring investors want to know why.

Is it because the Associated Press is reporting that the company's feature film The Call collected $4.9 million in box office receipts over the weekend for a grand-total, three-week haul of...$39.6 million? Unlikely.

Or could it be that investors are clamoring for a piece of Sony action as the company's much-anticipated PlayStation 4 gaming console comes to market? Possibly. The fact is, the imminent arrival of a new round of console upgrades has been doing good things for the stocks of most gaming-related companies: The shares of retailer GameStop and game makers Electronic Arts and Activision Blizzard are all up strongly in recent months. This, however, is not a phenomenon solely restricted to Sony -- and it doesn't explain why its stock is outperforming everyone else this morning.

Honestly, I suspect that the reason Sony is showing strength today is the worst reason of all: Investors like Sony stock today because some banker just said that it likes Sony stock, too.

Don't take advice from down under
South of the equator, analysts at Macquarie Group upgraded shares of Sony this morning, saying they expect the stock to outperform the market. Why? No one seems to know. Major media outlets have no details on the upgrade. StreetInsider.com -- usually a good source for this sort of thing -- says only that the upgrade happened but knows nothing more than that.

Here's what we do know: Whatever you think of the PlayStation 4 and its prospects, the company that makes the console is a dog of an investment. These shares have underperformed the S&P 500 by close to 30 percentage points over the past year, shedding fully a fifth of their value.

As for the company behind the ticker symbol, Sony is unprofitable today, and analysts have such a dim view of next year's return to profitability that the stock's current valuation, divided by next year's hoped-for (and uncertain) profits, works out to a sky-high forward P/E ratio of 85. Meanwhile, the amount of cash generated from operations at Sony is at its lowest level in four years.

Foolish final thought
None of this, suffice it to say, is good news for Sony or its investors. None of it seems to justify blindly following some analyst's advice and buying a stock that looks so eminently unbuyable.