Seoul’s benchmark index closed at its third straight all-time high on April 29, 2026, as a late-session reversal driven by a Financial Times report on AI memory demand erased early losses sparked by OpenAI’s revenue worries. Tokyo was offline for Japan’s Showa Day holiday, focusing the day’s action on Korea — where an Nvidia executive held back-to-back meetings with Samsung Electronics and SK hynix to build out a physical AI partnership, and LG Electronics reported a sharp first-quarter earnings beat.
Why today mattered
Wednesday’s session carried a clear narrative arc: the morning opened on doubt (an OpenAI executive’s reported concerns about revenue and user targets sent Wall Street tech lower overnight), and the afternoon pivoted to confidence (a Financial Times report reaffirmed that investors see memory chipmakers as the durable winners of the AI cycle). That intraday flip — from red to record — is the cleanest illustration yet of how the KOSPI‘s AI-linked rally is being tested and repriced on a day-by-day basis.
Korea: KOSPI logs its third consecutive record close
The KOSPI added 49.88 points, or 0.75%, to close at a fresh all-time high of 6,690.90, after touching an intraday peak of 6,716.20. Trade volume came in at 712.3 million shares worth 31 trillion won (about $21 billion), with advancing issues outnumbering decliners 478 to 362. Foreigners net sold 606.9 billion won — heavy selling concentrated in the electronics sector in the morning — but institutions absorbed 477.7 billion won and retail investors added 167.4 billion won. (Yonhap)
The intraday reversal explained
The KOSPI opened weaker, tracking overnight losses on Wall Street after a report that an OpenAI executive raised concerns over the company’s revenue and user targets. But the index turned higher in the afternoon once the Financial Times reported that investors are betting on a prolonged boom for memory chipmakers amid continued AI demand — at which point foreign net selling in electronics trimmed sharply from over 400 billion won to around 100 billion won. (Yonhap, citing Mirae Asset Securities analyst Seo Sang-young)
Stock movers
Samsung Electronics climbed 1.8% to 226,000 won, paring earlier losses after the afternoon report. SK hynix slipped 0.54% to 1,290,000 won. Beyond the headline chip names, the session’s biggest gainers were in adjacent AI infrastructure and defense:
- AI investment firm SK Square: +2.34% to 830,000 won
- Power equipment maker LS Electric: +4.4% to 273,000 won
- Shipbuilder HD Hyundai Heavy: +3.45% to 690,000 won
- Defense company Hyundai Rotem: +7.98% to 264,000 won
- Battery maker Samsung SDI: +4.71% to 712,000 won
- Chemicals group LG Chem: +3.43% to 407,500 won
On the losing side: Samsung Biologics fell 2.06%, Hanmi Semiconductor dropped 2.59%, and Korea Zinc slipped 1.41%. (Yonhap)
The catalyst behind the catalyst: Nvidia’s Physical AI push in Seoul
The afternoon reversal did not happen in a vacuum. On Wednesday, Madison Huang — Nvidia’s senior director of product and technical marketing for physical AI platforms — held meetings with executives from both Samsung Electronics and SK hynix to discuss cooperation in physical AI. Huang’s team oversees Nvidia Omniverse and robotics platforms that support the company’s push into industrial digitalization. Samsung and SK hynix are Nvidia’s primary memory-chip suppliers for AI training clusters. (Yonhap)
On Tuesday, Huang had already met LG Electronics and Hyundai Motor executives and delivered a lecture at Seoul National University. The signal embedded in this schedule is worth noting: Nvidia is methodically locking in the Korean industrial supply chain for its next platform cycle — chips, appliances, and automotive all in one visit.
LG Electronics: Q1 earnings beat adds to the Korea story
LG Electronics reported that first-quarter net income rose 14.8% year-on-year to 1 trillion won ($680.4 million). Operating profit surged 32.9% to 1.67 trillion won, while revenue grew 4.3% to 23.72 trillion won. The result was released during trading hours on Wednesday, adding a domestic earnings anchor to the broader AI-driven sentiment. (Yonhap)
Japan: Tokyo Stock Exchange closed — Showa Day
The Tokyo Stock Exchange was closed on April 29 for Japan’s Showa Day national holiday, marking the birthday of Emperor Showa. Trading resumes Thursday. The last confirmed close was Monday, April 27, when the Nikkei 225 crossed 60,000 for the first time, reaching a record closing high. (Nikkei Asia)
Investors watching Japan will return Thursday to a full plate: post-BOJ positioning (the central bank held rates in a split vote on April 28 while raising its inflation forecast to 2.8%), yen dynamics around 159, and any follow-through from Nikkei’s record-level positioning. (Nikkei Asia)
Macro variables in play
- AI demand cycle: The FT report on memory chipmaker outlook and Nvidia’s Seoul partnership offensive point in the same direction — the physical AI build-out is accelerating, and Korea is at its supply-chain core.
- OpenAI concern overhang: The early-session sell-off was triggered by a single executive comment. That it was fully reversed by an afternoon report shows the market’s underlying bid remains firm, but also how fragile the sentiment can be if AI capex expectations wobble.
- Won at 1,479 per dollar: The Korean won weakened 5.4 won against the dollar on the day, a modest softening that keeps the export competitiveness case intact but bears watching as it approaches 1,480. (Yonhap)
- Korean bond yields dip: 3-year Treasury yield fell 0.4 bps to 3.525%; 5-year government bond yield fell 1.2 bps to 3.706% — a mild bid for safety that reflects the early-session risk-off before the afternoon reversal.
- Iran war / energy: Japan’s absence from markets today delays but does not resolve the BOJ rate-hike question, which remains tied to oil prices and the Strait of Hormuz situation.
What to watch from here
- Tokyo’s return Thursday: With the Nikkei at 60,000+ and the BOJ signalling a potential June hike, Thursday’s Japan open will be the first full read on how investors re-price post-holiday.
- US big-tech earnings: Meta, Microsoft, and Apple results are due this week. Given Wednesday’s intraday dynamic, any revenue guidance miss could replay the morning dip more severely.
- Nvidia–Samsung–SK hynix follow-through: The Physical AI partnership meetings today were preliminary. Watch for any announcement of joint GPU cluster deployments or HBM supply commitments.
- KOSPI and the 6,700 level: The intraday high of 6,716.20 was turned back. Whether the index can sustainably break through 6,700 on the next session will depend on US earnings and any further AI capex headlines.
- KRW/USD around 1,480: A sustained move above this level could begin to weigh on imported-input cost inflation in Korea.
Related on ECONPLEX
- Indicators — Track KOSPI, USD/KRW, Korean Treasury yields and Nikkei 225 in real time.
- Economic calendar — US earnings dates and Thursday’s Japan market resumption.
- Glossary — Physical AI, Showa Day, BOJ split vote explained.
Three consecutive records, and the Nvidia catalyst is just getting started. Use ECONPLEX Indicators to follow KOSPI, USD/KRW, and Nikkei 225 as Tokyo reopens Thursday, and check the Calendar for US big-tech earnings that will set the tone for next week.
Sources: Yonhap, Nikkei Asia. All figures cross-checked against linked reports as of April 29, 2026 KST.