The KOSPI jumps more than 4 percent in early trade to regain the 5,700 level. Foreign and institutional buying flows in as investor sentiment improves toward artificial intelligence and semiconductor shares, triggering a buy sidecar.

As of 10:15 a.m. on Monday, the KOSPI is up 232.55 points, or 4.25 percent, from the previous session to 5,702.02.

The Korea Exchange triggers a buy sidecar at 10:13:53 a.m. on Monday, temporarily suspending the effectiveness of programme buy orders on the main board.

The move follows a more than 1-minute stretch in which KOSPI200 futures rise 5.05 percent to 893.02 from a reference price of 850.02. Programme buy orders are suspended for 5 minutes.

By investor type, foreign investors and institutions are net buyers of 454.3 billion won and 269.3 billion won, respectively, lifting the index. Retail investors are net sellers of 751.9 billion won.

Among the top market-cap stocks, semiconductor shares stand out. Samsung Electronics is trading at 223,750 won, up 5.05 percent from the previous session, and SK Hynix is up 7.76 percent to 1,374,000 won.

SK Square is also surging 11.31 percent to 856,000 won, while Samsung Electro-Mechanics is up 9.57 percent to 1,225,000 won. LG Energy Solution, Hyundai Motor and Samsung Life are also rising.

Samsung Biologics, however, is down 4.41 percent at 1,388,000 won, while KB Financial Group is off 0.61 percent at 146,300 won.

The KOSDAQ is also strong. At the same time, the KOSDAQ is up 30.39 points, or 4.18 percent, from the previous session at 757.60.

In the Seoul foreign exchange market, the won is trading at 1,325.10 per dollar, up 1.90 won from the previous session.

The domestic stock market is seen as being influenced by improved investor sentiment toward AI and semiconductor shares in U.S. markets the previous day, following the release of an initial public offering filing by AI company Anthropic. Expectations of easing tensions in the Middle East and a moderation in the rise in international oil prices also helped revive risk appetite.

The KOSPI has recently seen sharp volatility. The index, which had slipped to the 5,500 level, has moved back above 5,700 in a short period, and intraday swings have widened. Buying appears to be concentrated in large semiconductor shares rather than small and mid-cap stocks.

Han Ji-young (한지영), a researcher at Kiwoom Securities, said the KOSPI, which held the 5,500 level during last week's roller-coaster market, saw volatility increase after ending the previous session at the 5,400 level following a drop of more than 1 percent. She also said stock price instability in AI shares has eased during the recent correction, and the KOSPI earnings consensus has been maintained without significant damage, with the 2027 operating profit consensus holding in the 1,330 trillion won range for three weeks.