South Korean stocks finished almost flat Thursday, as investors took to the sidelines ahead of Samsung Electronics's earnings guidance for the second quarter and on a sharp fall in global oil prices, analysts said. The Korean won fell against the US dollar.

After a choppy session, the benchmark Korea Composite Stock Price Index edged up 0.54 point, or 0.02 percent, to close at 2,387.81.

Trade volume was moderate at 298 million shares worth 4.69 trillion won ($4.05 billion), with losers outnumbering gainers 423 to 379.

The local stock market opened lower, as oil prices suffered a sharp drop overnight, triggering a sell-off in energy stocks on the US stock market.

Also, investors are closely watching earnings reports to be delivered by key players, such as Samsung Electronics.

Samsung and other tech firms may deliver sound second-quarter earnings. Samsung, the world's largest manufacturer of smartphones, is set to release its second-quarter earnings guidance this week.

"Overnight falls in global oil prices are causing worries that the market will undergo expanded volatility," said Kim Byong-yeon, an analyst at NH Investment & Securities.

Institutional investors posted a selling binge by offloading a net 400 billion won.

Market heavyweights traded mixed.

Samsung Electronics, the top market cap here, rose 1.01 percent to end at 2,403,000 won, and SK hynix, a major chipmaker, gained 0.15 percent to 68,100 won.

POSCO, the top steelmaker, shed 0.51 percent to end at 294,000 won, and SK Innovation, the top refiner in the country, fell 0.94 percent to 158,500 won.

The state-run Korea Electric Power gained 0.24 percent to finish at 42,100 won.

Automakers continued to slide.

Hyundai Motor, the No. 1 automaker, fell 0.32 percent to end at 155,500 won amid concerns that its sales in China remained in a slump over a diplomatic row between Beijing and Seoul over the deployment of a US missile defense system.

AmorePacific, the nation's leading cosmetics maker, slumped 1.34 percent to end at 295,500 won.

The local currency closed at 1,157.40 won against the US dollar, down 6.9 won from the previous session's close. (Yonhap)