South Korean stocks snapped their weeklong winning streak Friday as foreigners and institutions took a breather amid increased valuation pressure. The Korean won fell against the US dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) fell 1.38 points, or 0.36 percent, to close at 3,131.88 points.

Trading volume was moderate at about 1.8 billion shares worth some 14.6 trillion won ($13 billion), with gainers outnumbering losers 537 to 305.

Foreigners sold a net 325 billion won, while retail investors purchased 726 billion won. Institutions offloaded a net 411 billion won.

The stock index started a tad higher on the back of the US Federal Reserve's assurance that it will continue supporting the economy without stoking inflation.

But stocks turned to negative territory as foreigners and institutions sold shares over concerns that stock prices have risen too high for their value.

"The KOSPI seems to be taking a breather as it rose for the sixth consecutive session," said HI Investment & Securities analyst Park Sang-hyun.

The Sino-American political tensions also put the KOSPI and its Asian peers under adjustment, he added.

In Seoul, market kingpin Samsung Electronics lost 1.3 percent to 83,600 won, and No. 2 chipmaker SK hynix shed 2.78 percent to 140,000 won.

Internet portal giant Naver added 0.52 percent to 383,500 won, and its rival Kakao increased 1.82 percent to 558,000 won. Leading carmaker Hyundai Motor stepped down 1.3 percent to 228,500 won.

Chemical maker LG Chem edged up 0.25 percent to 812,000 won, and rechargeable battery maker Samsung SDI climbed 0.91 percent to 663,000 won.

Pharmaceutical firm Samsung Biologics advanced 0.92 percent to 770,000 won, but Celltrion declined 0.64 percent to 309,500 won.

The local currency closed at 1,121.2 won to the US dollar, down 4 won from the previous session's close. (Yonhap)