South Korea's state pension fund has an overwhelming exposure to the country's top four conglomerates, data showed Wednesday, raising urgency for the fund to diversify its investment portfolio.

The National Pension Service, the country's top institutional investor, allocated some 74 percent of its stock investment to the country's top four conglomerates -- Samsung Group, Hyundai Group, SK Group and LG Group, according to the data compiled by CEO Score.

As of end-September, the NPS has 52 trillion won ($45.2 billion) worth of stock in the country's top 30 conglomerates. The data only includes stakes worth 5 percent or higher.

It invested in 10 affiliates of Samsung Group, which took up

35.9 percent of its stock portfolio. Its exposure to Hyundai Motor Group was 15.1 percent, followed by SK Group with 13.5 percent. LG Group took up 13.5 percent of the volume.

As of end-June, the NPS invested a total of 95.82 trillion won in stock.

By individual affiliates, the NPS's exposure to Samsung Electronics Co., the country's top market cap, reached 13.6 trillion won, followed by Hyundai Motor Co., SK hynix Inc. and SK Telecom Co. (Yonhap)