KOSPI extended gains on the 17th. Despite weakness on Wall Street and uncertainty over South Korea–U.S. negotiations, it closed slightly higher and again set a record closing high. Expectations that the expansion of artificial intelligence (AI) infrastructure will benefit not only semiconductors but also energy storage systems (ESS) spread to secondary batteries, sending battery stocks broadly higher and helping defend against a pullback in the index.
On the 17th, the KOSPI closed at 3,748.89. It opened lower at 3,732.76, down 15.61 points (0.42%) from the previous session, but turned higher intraday to set a new all-time closing high. In the morning, it successively topped 3,760 and 3,780 and touched 3,794.87, raising hopes of breaking 3,800. It surrendered much of its gains with just 6 points to go, leaving a bit of disappointment.
The KOSPI opened lower on the day on spillover weakness from Wall Street amid concerns over U.S. regional banks, but turned higher during the session. Foreign investors switched to net buyers intraday, purchasing a net 299.8 billion won and leading the index higher. Institutions and individuals were estimated to have net sold 233.6 billion won and 85.2 billion won, respectively.
The KOSPI appears to be soaring on expectations for a semiconductor "supercycle," the possibility of U.S. rate cuts, a South Korea–U.S. tariff deal, and hopes for a MoneyMove driven by real estate market regulations. In particular, since breaking above the 3,300 level in mid-September, it has been hitting fresh highs day after day.
By stock, semiconductor shares such as Samsung Electronics and SK hynix, buoyed by the AI frenzy, also surged on the day. SK hynix closed up 2.87% at 462,500 won. It was the third straight session of gains. Samsung Electronics also rose slightly for a second day, closing at 97,900 won.
In addition, secondary battery stocks rebounded across the board, adding momentum to the index. As ESS is cited as an essential device to stabilize data center power grids, buying concentrated in secondary batteries. Combined with news of a rise in global electric vehicle sales in September, shares of No. 3 by market cap LG Energy Solution rose more than 3% on the day.
Beyond LG Energy Solution, shares of Samsung SDI, considered a leading KOSPI secondary battery stock, also rose more than 8% on the day. Shares of L&F, a company specializing in secondary battery materials, climbed 12.8%. In contrast, shares of Samsung Biologics, Doosan Enerbility, and Hanwha Aerospace fell.
Kim Kyung-min, an analyst at Daishin Securities Co., said, "As investor buying has concentrated in large-cap KOSPI names at the top of market capitalization, such as semiconductors and secondary batteries, the index has risen in tandem," adding, "Overall, 690 decliners outnumbered 210 gainers by more than three to one, showing a pronounced skew."
The KOSDAQ index fell. It closed at 859.54, down 5.87 points (0.68%) from the previous day. The index opened at 862.71, down 2.70 points (0.31%) from the day before, and briefly turned higher intraday, but gave back all afternoon gains. Institutions net sold 131.7 billion won, dragging the index lower.
With the electric vehicle industry rebounding and an AI tailwind, shares of ECOPRO BM and Ecopro jumped 12.59% and 27.04%, respectively, but pharmaceutical and biotech stocks, which account for a large share of KOSDAQ market capitalization, fell. Shares of Peptron, PharmaResearch, LigaChem Biosciences, and Sam Chun Dang Pharm all declined.
Meanwhile, in the Seoul foreign exchange market, the won-dollar exchange rate stood at 1,421.50 won as of 4 p.m., up 0.23% from the previous session.