The South Korean stock market extended its winning streak to a seventh session on Tuesday, as investor appetite for risk strengthened over better-than-expected efficacy of a COVID-19 vaccine by US pharmaceutical giant Pfizer.

The Korean won fell against the US dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) rose 5.63 points, or 0.23 percent, to close at 2,452.83.

Trading volume was moderate at about 1.4 billion shares worth some 17.7 trillion won (US$15.9 billion), with gainers outnumbering losers 546 to 297.

Foreigners bought a net 157 billion won, with retail investors purchasing a net 189 billion won, while institutions offloaded a net 329 billion won.

Stocks traded choppy after the KOSPI's weeklong gains.

Index rebounded to close at an over 2-year high, marked by strong advances by travel and fuel stocks that followed Pfizer's vaccine test results. Contact-free tech, chemical and pharmaceutical stocks slumped, after having soared amid the global COVID-19 resurgence.

Local stocks were affected by US top infectious disease expert Anthony Fauci's statement that the Pfizer vaccine shot will have a "major impact," fueling investor optimism that the vaccine could be deployed by the end of the year.

"Pfizer's third-phase clinical test results seem to have raised hopes for a normal business year in 2021, increasing investor appetite for risky assets," Kiwoom Securities analyst Seo Sang-young said.

In Seoul, most large caps closed lower.

Market bellwether Samsung Electronics closed flat at 60,200 won, while No. 2 chipmaker SK hynix gained 0.58 percent to 86,500 won.

Internet portal giant Naver sank 5.03 percent to 283,000 won, with its rival Kakao dropping 4.17 percent to 356,000 won.

Leading chemical maker LG Chem retreated 4.36 percent to 702,000 won, and rechargeable battery maker Samsung SDI closed flat at 533,000 won.

Top pharmaceutical firm Samsung Biologics shed 1.18 percent to 752,000 won, and Celltrion dipped 2.98 percent to 276,500 won.

Hyundai Motor, the country's largest automaker, climbed 0.58 percent to 173,500 won, while top steelmaker Posco advanced 1.28 percent to 237,000 won.

The local currency closed at 1,115.1 won per dollar, down 1.2 won from the previous session's close.

Bond prices, which move inversely to yields, closed lower. The yield on three-year Treasurys rose 1.7 basis points to 0.976 percent, and the return on the benchmark five-year government bond added 3.4 basis points to 1.306 percent. (Yonhap)