South Korean stocks opened higher Wednesday on US stock gains, following a US drugmaker's announcement that its vaccine turned out effective against the spreading virus variant.

The benchmark Korea Composite Stock Price Index (Kospi) rose 11.25 points, or 0.34 percent, to trade at 3,297.93 points as of 9:15 a.m.

The Kospi got off to a bullish start, taking a cue from Moderna's announcement that its COVID-19 vaccine produced protective antibodies against the highly contagious delta variant.

Overnight, the tech-heavy Nasdaq Composite added 0.19 percent, and the Dow Jones Industrial Average and the S&P 500 both climbed 0.03 percent.

In Seoul, market bellwether Samsung Electronics gained 0.25 percent, while No. 2 chipmaker SK hynix jumped 2.8 percent.

Internet portal operator Naver lost 0.24 percent, while giant pharmaceutical firm Samsung Biologics moved up 0.24 percent.

Top automaker Hyundai Motor decreased 0.21 percent, but leading chemical firm LG Chem increased 2.15 percent.

The local currency was trading at 1,131.25 won against the US dollar, down 2.75 won from the previous session's close. (Yonhap)