The European Commission said on Tuesday it had opened an in-depth investigation of the sale of the Luxembourg unit of fallen Franco-Belgian bank Dexia to an investor linked to the Qatari royal family. \"Given that the proposed sale is the result of exclusive negotiations with one private investor and that the Commission does not have enough information on the valuation of the carved-out businesses at this stage, the Commission has opened an in-depth investigation to assess whether the price of the transaction\" is in line with its market valuation, it said in a statement.