South Korean stocks slumped for the third consecutive day Thursday as investors sold stocks to lock in gains despite the US Federal Reserve's soothing comments. The Korean won rose against the US dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) fell 7.4 points, or 0.23 percent, to close at 3,174.07 points.

Trading volume was moderate at about 1.2 billion shares worth some 18.8 trillion won ($17 billion), with losers outnumbering gainers 472 to 381.

Foreigners sold a net 14 billion won, while retail investors purchased 34 billion won. Institutions offloaded a net 15 billion won.

The stock index got off to a strong start as the US Federal Reserve said Wednesday (local time) that it would not roll back its asset-buying programs despite the current "transitory" signs of inflation.

But the KOSPI erased earlier gains and turned lower following US President Joe Biden's congressional speech about increasing taxes on the rich.

"Local stocks advanced in the early morning after the FOMC's dovish signal but turned to losses in the absence of further positive events," said Mirae Asset Securities analyst Seo Sang-young.

In Seoul, top cap Samsung Electronics lost 0.49 percent to 81,700 won and No. 2 chipmaker SK hynix closed unchanged at 130,000 won.

Giant internet portal operator Naver shed 1.87 percent to 366,500 won, and its rival Kakao retreated 2.09 percent to 117,000 won.

Pharmaceutical giant Samsung Biologics climbed 1.14 percent to 800,000 won, but Celltrion move down 0.56 percent to 268,500 won.

Leading chemical firm LG Chem soared 6.85 percent on its record earnings jump, and top automaker Hyundai Motor declined 1.81 percent to 217,500 won.

The local currency closed at 1,108.2 won against the US dollar, up 4.8 won from the previous session's close. (Yonhap)