South Korean shares hit the highest in 33 months Wednesday on a rally in bio stocks amid concerns over a flare-up of new coronavirus outbreaks. The Korean won surged to a 29-month high against the US dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) rose 6.49 points, or 0.26 percent, to close at 2,545.64. The reading marks the highest closing since 2,568.54 points on Feb. 1, 2018.

Trading volume was moderate at about 911 million shares worth some 13.3 trillion won ($12 billion), with gainers outnumbering losers 490 to 341.

Foreigners purchased a net 95 billion won, extending their buying streak to a 10th session, while retail investors sold a net 126 billion won. Institutions bought a net 52 billion won.

"Investor's buying mode seems to have reignited after the KOSPI took a breather yesterday, with COVID-19 vaccine optimism still running high in the markets," said Hana Financial & Investment analyst Lee Young-gon.

Strong bio gains led the KOSPI's gain amid surging new COVID-19 cases at home, while chip and auto heavyweights dropped.

South Korea's new coronavirus cases hit a nearly 3-month high Wednesday, with authorities warning that infections may further increase due to cluster infections in greater Seoul.

In Seoul, most large caps closed mixed.

Market bellwether Samsung Electronics lost 1.37 percent to 64,800 won, and No. 2 chipmaker SK hynix slipped 0.1 percent to 98,000 won.

Top pharmaceutical firm Samsung Biologics spiked 4.91 percent to 812,000 won, and Celltrion gained 1.75 percent to 291,000 won after announcing its production expansion plan.

Internet portal giant Naver jumped 2.18 percent to 281,000 won, with its rival Kakao up 0.97 percent to 365,500 won.

Leading chemical maker LG Chem advanced 3.35 percent to 709,000 won, and rechargeable battery maker Samsung SDI gained 1.52 percent to 501,000 won.

Hyundai Motor, the country's largest automaker, fell 1.64 percent to 179,500 won.

The local currency closed at 1,103.8 won per dollar, up 2.8 won from the previous session's close and the highest since 1097.8 on June 15, 2018.

Bond prices, which move inversely to yields, closed higher. The yield on three-year Treasurys lost 1.1 basis points to 0.949 percent, and the return on the benchmark five-year government bond fell 1.7 basis points to 1.280 percent. (Yonhap)