Seoul shares close at new high on tech rally amid AI optimism

South Korean stocks extended a rally to a fresh all-time high Monday, driven by strong gains in stocks related to artificial intelligence (AI). The local currency rose against the U.S. dollar.

The benchmark Korea Composite Stock Price Index (KOSPI) added 311.85 points, or 3.68 percent, to close at 8,788.38, after hitting a new intraday high of 8,874.16.

The index opened at a record high and extended its gains, prompting the Korea Exchange (KRX) to activate a buy-side sidecar, which suspended program trading of KOSPI stocks for five minutes at around 11:30 a.m.

Trade volume was heavy at 618.17 million shares worth 69.4 trillion won (US$46.1 billion), with losers outnumbering winners 712 to 194.

Institutions and individuals scooped up a net 2.53 trillion won and 377.31 billion won, respectively, while foreigners unloaded a net 2.91 trillion won.

The United States and Iran have been negotiating over a draft agreement aimed at ending the conflict and reopening the Strait of Hormuz, but the lack of a meaningful breakthrough over the weekend helped lift oil prices higher.

Despite the lack of progress in the Middle East talks, chipmakers rallied on expectations that the AI-driven semiconductor boom will continue.

South Korea's exports surged 53 percent from a year earlier to a new monthly high of US$87.8 billion in May, driven by the semiconductor supercycle, government data showed.

Robot and AI-related stocks gained on expectations of potential partnership opportunities ahead of U.S. chip giant Nvidia Corp. CEO Jensen Huang's visit to South Korea later this week.

During a Computex conference in Taipei, Huang said Nvidia's Vera central processing unit (CPU) designed for AI agents will be equipped with high-bandwidth memory (HBM) chips supplied by Samsung Electronics, SK hynix and Micron.

"Huang's announcement on the Vera chip, coupled with expectations surrounding his upcoming visit to South Korea, has boosted investor sentiment toward chipmakers. Samsung Electronics, whose shares had recently underperformed SK hynix, posted a sharp rally," Lee Kyung-min, an analyst at Daishin Securities, said.

"Large-cap AI and robotics-related stocks appear to be leading the broader market gains on expectations of potential cooperation with Nvidia," he added.

Market bellwether Samsung Electronics jumped 10.09 percent to a record high of 349,000 won, while rival chipmaker SK hynix climbed 1.29 percent to 1.36 million won.

Top automaker Hyundai Motor gained 3.73 percent to 750,000 won, and AI investment firm SK Square rose 1.87 percent to 1.25 million won.

LG Electronics skyrocketed 29.86 percent to 380,500 won, and internet portal operator Naver surged 16.03 percent to 271,500 won amid reports that their chiefs could meet Huang to discuss AI partnership.

The Korean won was quoted at 1,504.3 won against the U.S. dollar at 3:30 p.m., up 3.6 won from the previous session.

Bond prices, which move inversely to yields, closed lower. The yield on three-year Treasurys rose 5.9 basis points to 3.790 percent, while the return on the benchmark five-year government bonds added 7.2 basis points to 3.996 percent.

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