The benchmark Korea Composite Stock Price Index shed 10.11 points, or 0.4 percent, to close at 2,546.36. Trading volume was high at 521 million shares worth 6.17 trillion won ($5.53 billion), with losers outpacing gainers 450 to 344.
The index had soared 1.31 percent Wednesday to close at a new record of 2,556.47 points, aided by gains in Samsung and other tech stocks.
"Chipmakers and Apple-related stocks, which have been enjoying sharp gains, remained dull in the US market," said Seo Sang-young, a researcher at Kiwoom Securities Co. "This factor prodded investors to seek after profit in the South Korean market as well."
Individuals scooped up a net 155.3 billion won, while institutions sold a net 195 billion won. Foreigners sold more shares than they bought at 1.77 billion won.
Top cap Samsung Electronics moved down 0.28 percent at 2,853,000 won, and No. 2 chipmaker SK hynix lost 2.23 percent at 83,400 won. LG Electronics decreased 0.76 percent at 91,600 won.
Insurance companies also had a bearish day, with Samsung Life Insurance losing 2.18 percent at 134,500 won and Hanwha Life Insurance falling 1.68 percent at 7,620 won.
No. 1 carmaker Hyundai Motor declined 0.31 percent at 160,000 won, while its auto-parts arm Hyundai Mobis added 0.38 percent at 266,000 won. Kia Motors fell 0.57 percent at 35,150 won.
LG Chem, the top chemical firm, advanced 1.33 percent at 420,000 won on speculation that its battery sales in China will recover.
Top cosmetics maker AmorePacific also increased 2.28 percent at 314,500 won.
The local currency closed at 1,114.40 won against the US dollar, up 0.1 won from the previous session's close.
Bond prices, which move inversely to yields, closed higher. The yield on three-year Treasurys shed 1.4 basis points to 2.126 percent and the return on benchmark five-year government bonds fell 2.2 basis points to 2.350 percent. (Yonhap)