By Christopher Bjork MADRID--Banco Santander SA (SAN) Thursday said it plans to file the prospectus for the planned initial public offering of shares in its Mexican unit in the coming days with the Mexican market regulator and with the U.S. Securities and Exchange Commission. In a regulatory filing, Santander said it had not yet determined how much of the unit it plans to sell in the offering, though it added that the Santander group will retain majority control. The shares will list simultaneously in Mexico and on the New York Stock Exchange, the bank added. Previously, Santander had said it planned to sell 25% of the unit in the deal, and people familiar with the deal in May said that the bank was seeking a valuation for the whole of Santander Mexico of between $15 billion and $20 billion. Bloomberg News reported Wednesday that Santander may raise up to $4 billion in the IPO, by selling between 25% and 30% of the unit. Write to Christopher Bjork at christopher.bjork@dowjones.com
