South Korea's national pension and other state funds sold more than 15 trillion won ($13.2 billion) worth of shares in the first quarter of the year due to their portfolio rules, data showed Wednesday.

Net selling of shares listed on the main bourse by the National Pension Service and other state funds came to 15.7 trillion won in the January-March period, according to the data from the Korea Exchange.

It accounted for 56 percent of institutional investors' total net selling worth 27.9 trillion won during the period.

In contrast, foreign investors bought a net 8.3 trillion won worth of local stocks, with retail investors' net buying reaching 37.1 trillion won.

Top-cap Samsung Electronics Co. was the most-sold stock by pension and other state funds during the three-month period with 5.3 trillion won. Top chemicals firm LG Chem came next with 1.1 trillion won, followed by chip giant SK hynix with slightly over 1 trillion won and leading automaker Hyundai Motor with 831 billion won.

National pension and other state funds remained net sellers for most of the first quarter. In particular, they were net sellers for 51 sessions between Dec. 24 and March 12, their longest selling streak.

Those funds turned net buyers on March 15 and 16, but they again became net sellers for the following 10 days.

Their massive net selling results from their portfolio management rules that require them to dispose of stocks should their equity ratio surpass certain ceilings.

For instance, the NPS has a target of holding stocks amounting to 16.8 percent of its total assets this year, but its share ratio came to 21.2 percent as of the end of last year, resulting in net selling. (Yonhap)