Seoul shares posted their biggest drop in over four months on Thursday, retreating fast from a record hit earlier in the session, on worries shares such as steel maker POSCO have risen too far. Concerns about oil prices also played a role, hitting power provider Korea Electric Power Corp (KEPCO).
But Hyundai Motor Co surged after posting much stronger than expected quarterly earnings. The benchmark KOSPI passed 2,000-points for the first time this week, bringing its gain to nearly 40 percent so far this year as of the previous close on optimism about the outlook for the economy and corporate profits.
But the main index's relative strength index hit 82.7 on Wednesday, well above the 70-point level at which a stock or index is seen as technically overbought. The index fell to 60.5 at the close.
Moody's Investors Service on Wednesday raised its rating on South Korea by one notch. The benchmark Korea Composite Stock Price Index (KOSPI) dropped 2.03 percent to end at 1,963.54 points, after earlier in the day hitting a record 2,015.48, its fifth consecutive intraday peak.
That marked the KOSPI's biggest one-day percentage drop since falling 2.7 percent on March 5, when the index was in the midst of a global market correction caused by worries about the US subprime mortgage sector.
Foreign investors have remained very heavy sellers this month, unloading a net 374.5 billion won ($409.9 million) worth of shares in the KOSPI, which brought their total for the month to 3.12 trillion won.
Steel maker POSCO Co Ltd dropped 4.42 percent to 541,000 won. Hyundai Heavy Industries Co slumped 2.64 percent to 368,500 won. Shares in the world's biggest shipbuilder had surged 200.4 percent. Hyundai Motor rose 2.12 percent to 82,000 won after the country's biggest auto maker posted a surge in quarterly profit on Thursday on improved domestic sales and cost cutting among other factors. SK Telecom Co gained 0.7 percent to 217,000 won.