The benchmark Korea Composite Stock Price Index increased 23.61 points, or 0.99 percent, to 2,409.68 as of 11:20 a.m., after soaring to as high as 2,410.58 at one point.
On Friday, US stocks closed at fresh record highs, with the S&P 500 inching up to surpass the 2,500-point mark for the first time.
Most large caps improved, with market kingpin Samsung Electronics adding 2.38 percent and SK hynix, a major chipmaker, advancing 3.24 percent.
Naver, South Korea's top Internet portal operator, also gained 2.63 percent.
LG Chem, the country's top chemicals firm, meanwhile, lost 1.25 percent.
The local currency was trading at 1,127.50 won against the US dollar, up 4.20 won from the previous session's close. (Yonhap)