RIMM up 50% this month.  HPQ up 10% since gapping down after the Autonomy debacle.  BBY up 6.6% today.

What is powering the sudden surges in these perennial underperformers?  Are these companies turning it around?  Are these companies fundamentally better than they were a week ago?

Josh Brown at the Reformed Broker just answered this question in his blog post, “Here is an incontrovertible fact“, in which he discusses the real reason behind the sudden resurgence in these stocks.  The answer is market sentiment.

Stocks move on short term supply and demand.  When the majority of short-term market participants are on the same side of the trade, the price will almost always move in the opposite direction.  The herd is always wrong.  Too many participants have thrown these dogs out, and some real Johnny-come-latelies were recently shorting them.  But sorry to break it to you Johnny, nothing goes straight to zero.  There are always short covering squeezes, glimmers of hope, and market sentiment shifts.  And the market sentiment has shifted for all of these issues.  These dogs are barking.

You know what happens when one dog starts barking in the neighborhood, all the other dogs start barking as well.  So don’t be surprised if some of these other dogs start gathering some short-term interest.

RadioShack (RSH)

Advanced Micro Devices (AMD)

Alcoa Inc. (AA)

Alcatel-Lucent (ALU)

ITT Educational Services (ESI)

Apollo Group (APOL)

Zynga (ZNGA)

Supervalu (SVU)

J.C. Penney (JCP)

The bottom line is that there may be some short-term upside in some of these issues, but don’t get married to any of them.  Just because the dogs are barking, doesn’t mean they don’t all have fleas.