With the artificial intelligence (AI) bubble theory resurfacing, the KOSPI index fell below the 4,100 level on the 15th for the first time in seven trading days. By contrast, the KOSDAQ index inched up and closed around the 930 level.
The KOSPI on the day closed at 4,090.59, down 76.57 points (1.84%) from the previous trading day. After opening at 4,053.74, a sharp drop of 113.42 points (2.72%) from the day before, the index trimmed some losses on intraday individual buying but ultimately failed to hold 4,100.
In the main board, individual investors alone supported the index with a net purchase of 1.25 trillion won. Foreigners and institutions, on the other hand, showed selling dominance with net sales of 960 billion won and 300 billion won, respectively.
Semiconductor shares struggled on worries over AI profitability. A candid remark by Broadcom CEO Hock Tan that "the gross margin on AI revenue is lower than on non-AI revenue" shook investor sentiment toward the AI industry. In addition, Oracle's comments raising the possibility of rejecting imports of Nvidia's H200 chips into China weighed on semiconductor stocks across the board.
Samsung Electronics (-3.76%), SK hynix (-2.98%), DB HiTek (-3.25%), and EO Technics (-6.67%) all closed lower.
Lee Kyung-min, a researcher at Daishin Securities Co., said, "The crux of the current AI bubble and profitability deterioration debate is 'separating the wheat from the chaff,'" adding, "A strategy of selectively increasing exposure to corporations in the Alphabet value chain and those with solid financial soundness and margins remains valid."
Space-themed stocks were strong on the day. The Wall Street Journal (WSJ) reported that SpaceX, the space exploration company led by Tesla CEO Elon Musk, has begun the process of selecting advisers for an initial public offering (IPO). SeAH Besteel Holdings (9.39%) and Spear (5.99%), cited as potential suppliers of special alloys, finished higher.
Of the top 10 stocks by market capitalization on the main board, nine fell. Except for Samsung Biologics (4.73%), Hyundai Motor (-2.65%), HD Hyundai Heavy Industries (-3.84%), and Doosan Enerbility (-3.26%) all ended the session at lower prices than the previous day.
The KOSDAQ index closed at 938.84, up 1.50 points (0.16%) from the previous trading day. Opening at 925.60, down 11.74 points (1.25%) from the previous session, the KOSDAQ index at one point threatened to top 940 on individual net buying during the session.
In the KOSDAQ market, individuals were net buyers of 200 billion won. Foreigners and institutions showed net selling of 23 billion won and 130 billion won, respectively.
Among the top 10 KOSDAQ stocks by market cap, six closed higher. Alteogen (0.69%), EcoPro BM (2.1%), and ABL Bio (3.05%) rose, while Kolon TissueGene (-1.23%) and HLB (-2.18%) closed lower.
The won-dollar exchange rate in the Seoul foreign exchange market closed weekly transactions at 1,471 won as of 3:30 p.m., down 2.7 won from the previous day.