South Korean stocks opened almost flat Thursday after the US Federal Reserve chief hinted at more rate hikes this year.

The benchmark Korea Composite Stock Price Index inched up 3.15 points, or 0.12 percent, to 2,585.78 in the first 15 minutes of trading.

Overnight, all three major US equity indexes ended in negative territory, after Fed Chair Jerome Powell said during his congressional testimony that the central bank remained focused on wrestling down inflation back to its 2 percent target and that there could be two more quarter-percentage-point hikes this year.

"Nearly all FOMC participants expect that it will be appropriate to raise interest rates somewhat further by the end of the year," he said.

The Dow Jones Industrial Average fell 0.3 percent, the S&P 500 went down 0.52 percent and the Nasdaq Composite declined 2.05 percent.

In Seoul, mega-cap shares opened mixed.

Market behemoth Samsung Electronics added 0.85 percent and SK hynix gained 0.43 percent. Top battery maker LG Energy Solution increased 1.25 percent and Samsung SDI climbed 0.14 percent.

Auto stocks lost ground, with Hyundai Motor retreating 1.23 percent and Kia falling 0.83 percent.

The local currency was trading at 1,288.4 won against the US dollar at 9:15 a.m., up 3.6 won from the previous session's close. (Yonhap)