The Korean won gained in the local platform while bond yields fell.
At 06:33 GMT, the KOSPI was down 11.07 points or 0.45 percent at 2,469.48. The index erased earlier gains as Thursday was expiration day for both KOSPI futures and options.
The won was quoted at 1,089.1 per dollar on the onshore settlement platform, 0.15 percent firmer than its previous close at 1,090.7.
In offshore trading, the won was quoted at 1,087.59 per US dollar, down 0.35 percent from the previous day, while in one-year non-deliverable forwards it was being transacted at 1,081.85 per dollar.
MSCI's broadest index of Asia-Pacific shares outside Japan was up 0.15 percent, after US stocks ended the previous session with mild losses. Japanese stocks weakened 0.28 percent.
The KOSPI is up around 22.4 percent so far this year, and down by 2.97 percent in the previous 30 days.
The current price-to-earnings ratio is 12.10, the dividend yield is 1.28 percent and the market capitalisation is 1,242.04 trillion won.
The trading volume during the session on the KOSPI index was 313,627,000 shares, and of the total traded issues of 878, the number of advancing shares was 373.
Foreigners were net buyers of 372,566 million won worth of shares.
The U.S dollar has fallen 9.84 percent against the won this year. The won's high for the year is 1,075.71 per dollar on November 29 2017 and low is 1,211.8 on January 3 2017.
In money and debt markets, December futures on three-year treasury bonds rose 0.01 points to 108.31.
The Korean 3-month Certificate of Deposit benchmark rate was quoted at 1.66 percent compared with a previous close of 1.66 percent, while the benchmark 3-year Korean treasury bond yielded 2.075 percent, lower than the previous day's 2.08 percent.