South Korea's national pension fund plans to boost its stock investment in the coming years while cutting exposure to safer assets in order to raise its investment returns, welfare ministry said Friday. The National Pension Service, one of the world's major pension operators, would raise the portion of stocks to its overall investment portfolio to over 35 percent by 2019 from the 30.1 percent at the end of last year, according to the ministry which has a final say on the management of the country's largest institutional investor.