Superman Returns (PS2) sold 27,250 copies in January for a total of 219,250 copies in North America. This is less than half of what is currently projected by the stock price and I think momentum for this game will drop off significantly. Probably a good sell.
The Xbox 360 version's stock is currently at 36 DKP and falling, while the Xbox version is sitting at 31 DKP. This PS2 version is incredibly overvalued at 77. If you have any money on this game (or want to make money), sell before it tanks!
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