SHANGHAI - A Shanghai-listed fund that holds U.S. stocks took the unusual step of suspending trading on Friday, saying it was necessary to protect investors after prices hit record levels in a scramble for overseas assets. Trading in the exchange-traded fund (ETF) that tracks the MSCI USA 50 Index was halted for the afternoon session, after a one-hour suspension in the morning failed to reduce hefty price premiums. "We caution investors of the risks in the secondary market price premiums," the ETF's manager, E Fund Management Co said in a statement. "Investors who invest blindly could suffer major losses." ETFs trade like stocks on exchanges, with prices determined by supply...Keep on reading: China fund with US stocks halts trading to calm investor fever