Helped by a sharp drop in international oil prices and semiconductor tailwinds from Nvidia, the KOSPI index regained the 5,600 mark after four transactions.
On the 17th, the KOSPI index closed at 5,640.48, up 90.63 points (1.63%) from the previous transaction day. The index opened above 5,700 points and moved between the 5,630–5,710 range during the session. Although the gains narrowed somewhat just before the close, the market rose for a second straight transaction day.
Institutions led the index higher. Institutions were net buyers of 736 billion won, with brokerages buying a net 425.7 billion won and investment trusts and the National Pension Service buying a net 235.3 billion won and 84.5 billion won, respectively.
By contrast, individuals were net buyers of nearly 200 billion won early in the session but turned sellers after 9:30 a.m. and ultimately sold a net 570.8 billion won. It was the first day of net selling by individuals in three transactions. Foreign investors extended their net selling for a fifth straight transaction day. They also showed a selling advantage of 177.5 billion won on the day.
As international oil prices stabilized, risk asset investor sentiment recovered. Although the Middle East war continues, reports that some ships passed through the Strait of Hormuz and repeated emphasis by U.S. President Donald Trump on lifting the blockade, including asking five countries to dispatch forces to the strait, sent international oil prices lower. On the New York Mercantile Exchange (NYMEX), West Texas Intermediate (WTI) April futures settled at $93.5, down $5.21 (5.28%) from the previous day.
Nvidia's annual event, "GTC 2026," also provided a warm tailwind for the domestic stock market. On news that Nvidia Chief Executive Jensen Huang mentioned Samsung Electronics as a production partner for the next-generation artificial intelligence (AI) chip "Grok 3" at "GTC 2026," Samsung Electronics rose more than 2%.
Hyundai Motor, which Nvidia revealed as a collaborator on Autonomous Driving, also jumped 3% to close. Kia (3.27%), Hyundai WIA (6.28%), Hyundai AutoEver (0.6%), and SAMHYUN (13.64%) were also strong.
Meanwhile, as geopolitical risks eased, defense stocks fell, with Hanwha Aerospace down 5.42% and LIG Nex1 down 3.42%. Korea Aerospace Industries (KAI) alone rose 5.65% on news of an equity acquisition by Hanwha Group.
The KOSDAQ index closed at 1,136.94, down 1.35 points (0.12%). It rose to the 1,150 level during the session, but slid to the 1,130 level as sell orders emerged just before the close. By investor type, individuals were net buyers of 139.7 billion won, while foreigners and institutions were net sellers of 57.8 billion won and 36.4 billion won, respectively.