My guess is that it's related to the large quantity of open $52.50 puts expiring today/tomorrow. I watched the open interest at $52.50 jump recently and was thinking yesterday that rather than take a loss some of the large holders of those options were going to try and push the stock down below $52.50 at least temporarily today. Since there's no specific news and other retailers aren't being similarly hit, I suspect that's the most likely explanation (or else it's quite a coincidence.)
So...you might see a bit of a pop in the price off of the early morning lows later in the day as those same sellers start covering their shorts.
Excellent read as I was seeing the same thing. I feel like a big rally in this stockis due today as a result of teh option driven sell off. All teh big guys like this stock and will not let it sit down here for long. I Am adding to my position here and will be drooling if it lets me buy more at $52. I see $54 price today or Tuesday, so go strong longs as this company is great.