The KOSPI is strong in early trade as it extends gains after breaking above the 6,600 level for the first time. It also reset its 52-week intraday high.

The KOSPI stood at 6,648.90 as of 9:21 a.m. on April 28, up 33.87 points, or 0.51 percent, from the previous session.

The index opened up 31.77 points, or 0.48 percent, at 6,646.80 from the previous close and held its gains. It rose to as high as 6,672.32, setting a new 52-week high again.

Retail investors were net buyers of 202.1 billion won, supporting the index. Foreigners were net sellers of 218.6 billion won, and institutions were net buyers of 43.6 billion won.

Among the top stocks by market capitalisation, chipmakers were mixed. Samsung Electronics fell 1.00 percent to 222,250 won, while SK Hynix rose 1.39 percent to extend gains.

Other heavyweight stocks were mixed. LG Energy Solution rose 1.72 percent, Hyundai Motor gained 2.29 percent and SK Square climbed 2.53 percent. Doosan Enerbility fell 0.78 percent, Hanwha Aerospace slipped 1.51 percent, Samsung Biologics eased 0.20 percent and HD Hyundai Heavy Industries dropped 2.82 percent.

The KOSDAQ was down 14.68 points, or 1.20 percent, at 1,211.50 at the same time, as profit-taking emerged.

In the foreign exchange market, the won-dollar exchange rate fell 1.90 won, or 0.13 percent, from the previous session to 1,473.10 won.