Whoever said bears hibernate during the winter was lying.

Apple (AAPL 0.41%) is selling off yet again today, down more than 3% as of this writing, on no news whatsoever. Big Money investors apparently like other stocks more. Some are also betting against the Mac maker -- short interest is up from near zero a year ago to almost 2% today, according to data compiled by S&P Capital IQ.

I blame the iPad mini.

Apple has sold off mightily since CEO Tim Cook unveiled the device at an Oct. 23 press event:

^SPX Chart

^SPX data by YCharts.

The mini scares the Street. Not only because it's cheaper, but also because it lacks the Retina display that makes the newest iPads so crystal clear.

Scarier is that no one -- not even thieves -- seem to care about these shortcomings. According to a recent report from Citi, Apple's Q1 order book calls for adding twice as many minis to inventory as regular iPads. The same report also says that Apple likely sold out of all 10 million units it ordered. Fourth-generation iPads remain available.

And the good news?
if you're a long-term investor, this news isn't nearly as bad as it might seem. The mini is performing remarkably well despite formidable competitors:  Google's (GOOGL -1.59%) Nexus 7 tablet sold out shortly after its release while Amazon.com's (AMZN 0.80%) Kindle Fire HD topped the e-tailer's sales charts throughout the holiday shopping season.

Finally, there's math to consider. Appearances to the contrary -- a $499 fourth-gen iPad certainly seems like it would be more profitable -- Apple generates from six to eight more points of margin from the mini than its larger-screen peers. That's according to an iSuppli teardown analysis of device components and manufacturing costs.

Thus in punishing Apple for releasing the lower-cost mini, Wall Street is making a huge mistake. It's not the first time we've seen this, and it definitely won't be the last.