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What: Shares of teen fashion retailer Pacific Sunwear (Nasdaq: PSUN) popped 8% in intraday trading today on no apparent news.

So What: Your guess is as good as mine as to why there’s sudden, spiking interest in this teen retailer’s shares. The retail landscape’s fraught with difficulties these days, and Pacific Sunwear has reported dwindling sales and posted annual losses for the last two fiscal years, and annual comps for the year ended January 2010 plunged a nauseating 20%.

Now What: Investors should avoid becoming infected with unsubstantiated bullishness about Pacific Sunwear shares right now. It faces formidable competition in the teen retail space from companies like Abercrombie & Fitch (NYSE: ANF), Zumiez (Nasdaq: ZUMZ), Aeropostale (NYSE: ARO), and Buckle (NYSE: BKE), just to name a few. If there’s no apparent reason why Pacific Sunwear’s popping today, following suit and snapping up shares may be an unreasonable move investors could come to regret.

Interested in more info on Pacific Sunwear? Add it to your watchlist here by clicking here.

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Alyce Lomax does not own shares of any of the companies mentioned. The Fool has a disclosure policy. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.