South Korea's state-run pension fund has expanded its exposure to stocks with the portion of such investment topping 30 percent last year, data showed Thursday. The National Pension Service (NPS), the country's top institutional investor, said it held stocks valued at 128.32 trillion won (US$119.31 billion) at the end of last year, which account for 30.5 percent of its assets totaling 426.96 trillion won.