South Korean stocks dropped more than 2 percent Tuesday as foreign and institutional investors sought to cash in profits after the key stock index hit its all-time high the previous session. The Korean won fell against the US dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) fell 68.68 points, or 2.14 percent, to close at 3,140.31 points.

Trading volume was high at about 860 million shares worth some 21.6 trillion won ($19.5 billion), with losers outnumbering gainers 639 to 239.

Foreigners sold a net 2 trillion won, while retail investors purchased a net 4.2 trillion won. Institutions offloaded a net 2.3 trillion won.

The KOSPI undid most of the 2.18 percent gain the previous day, led by losses on tech and chemical heavyweights.

"Weak local currency fueled foreign investors' appetite to sell," Daeshin Securities analyst Lee Kyung-min said.

"Foreigners seem to have gone through a portfolio shuffle, selling their appreciated stocks and buying the less appreciated stocks," he added.

Most large caps closed lower.

Market bellwether Samsung Electronics lost 3.02 percent to 86,700 won, and No. 2 chipmaker SK hynix shed 4.44 percent to 129,000 won.

Top pharmaceutical firm Samsung Biologics gained 1.52 percent to 802,000 won, and Celltrion rose 0.47 percent to 322,500 won.

Internet portal giant Naver retreated 2.01 percent to 342,000 won, with its rival Kakao dipping 2.64 percent to 461,000 won.

Leading chemical maker LG Chem fell 3.54 percent to 955,000 won, and rechargeable battery maker Samsung SDI closed unchanged at 790,000 won.

Hyundai Motor, the country's largest automaker, declined 3.27 percent to 251,500 won.

The local currency closed at 1,106.6 won per dollar, down 5.8 won from the previous session's close.

Bond prices, which move inversely to yields, closed mixed. The yield on three-year Treasurys rose 0.1 basis point to 1.007 percent, while the return on the benchmark five-year government bond fell 0.5 basis point to 1.348 percent. (Yonhap)