south korean security services company sk shieldus co withdrew the prospectus for an initial public offering in seoul as market volatility damps investor demand for new shares worldwide the company said in a filing that it had difficulty obtaining proper valuation initial terms of the deal last month indicated the company and shareholders were aiming to raise as much as 105 trillion won 825 million by selling the stock at a range of 31000 won to 38800 won each seoul economic daily reported this week that institutional investors had offered to subscribe to the shares at a 2500028000 won range