Korean stocks extended gains Thursday morning, led by a rally in big-cap semiconductor shares.

After opening 2.96 percent higher, the benchmark Korea Composite Stock Price Index (KOSPI) rose 275.96 points, or 4.19 percent, to 6,855 as of 11:20 a.m.

Overnight, U.S. stocks tied to the artificial intelligence technology sector rose. The S&P 500 gained 0.26 percent, closing just shy of a record high, while the Nasdaq composite advanced 0.54 percent. In contrast, the Dow Jones Industrial Average edged down 0.04 percent.

In Seoul, blue-chip shares led the advance.

Market bellwether Samsung Electronics rose a sharp 5.48 percent, while its chipmaking rival SK hynix also jumped 7.55 percent.

SK Square, the parent of SK hynix, shot up 8.98 percent, and Samsung Electro-Mechanics, an electronics component affiliate of Samsung Electronics, surged 12.73 percent.

The Korean won was trading at 1,415.1 won against the U.S. dollar as of 11:20 a.m., up 3.4 won from the end of stock trading the previous day.