Seoul’s KOSPI surged past 7,000 intraday on AI memory-demand hopes tied to OpenAI’s upcoming ‘Astra’ model, then closed down 0.58% at 6,954.52 as retail investors dumped over 3 trillion won of stock. Oil and a US-Canada trade fight added pressure.
Korea’s KOSPI jumped 4.61% to 6,995.39 as OpenAI ‘Astra’ expectations powered Samsung Electronics and SK Hynix. Foreigners and institutions bought heavily while retail investors sold a near-record 8.26 trillion won.
The KOSPI closed at 6,687.21 (+1.64%) and the KOSDAQ surged 2.95% as foreign and institutional investors bought heavily on Fed rate-pause signals, while retail investors sold about $3.3 billion. Semiconductors and crypto-linked names led; banks and biopharma lagged.
The KOSPI sank 3.99% to 6,562.72 as US-Iran clashes near the Strait of Hormuz pushed Brent above $90 and US yields hit multi-month highs. Samsung Electronics and SK hynix fell over 4%, while biotech names surged to Korea’s 30% daily limit.
US CPI hits at 21:30-22:30 KST, roughly eleven hours before the KOSPI opens. Three channels carry the surprise into Seoul’s 9:00 a.m. session: US index futures and the SOX, the USD/KRW rate, and foreign investor flow direction. Here is how to read each one, with a worked example of reading a multi-session foreign-flow tape from August 2026.
The KOSPI opened down 2.6% and fell over 3% intraday before Samsung Electronics and SK hynix buybacks soaked up foreign and passive selling, lifting the index to close up 0.46% at 6,820. The KOSDAQ lagged as battery names slid.
Korea’s KOSPI fell 1.79% to 6,788.88 as AI chip heavyweights saw post-Nvidia profit-taking, while the KOSDAQ held flat. Retail investors bought the dip as foreigners and institutions sold, with new Fed Chair Kevin Warsh’s first Jackson Hole speech looming after the close.
Korean chip stocks can fall the morning after an Nvidia beat because the move was pre-positioned: the reaction runs through the after-hours print, guidance, overnight US futures and after-hours moves in other chip names before the 09:00 Seoul open. Here is the full transmission chain, with a worked example reading real August 2026 foreign-flow data into a purely hypothetical earnings night — heavy selling that fades to near flat, a de-risking backdrop whose post-result implications can cut more than one way.
The KOSPI rose for a third straight day as Nvidia’s earnings beat lifted chipmakers and battery names surged on ESS tender hopes, but a mid-session Bank of Korea rate hike trimmed the benchmark’s gain to 1.53% at 6,912.37.
The KOSPI reversed an early dip to close at 6,808.21 (+0.97%) as Samsung Electronics (+1.75%) and SK Hynix (+0.60%) advanced on cheaper oil and lower US yields. The KOSDAQ ended flat, with Nvidia earnings, a Bank of Korea rate decision, and Jackson Hole all looming this week.