Seoul — August 13, 2026. Published after the market close; index values are official closes, while individual-stock figures are intraday readings and the exchange rate is a same-day market reading rather than an official close.
The 30-second version
- The KOSPI surged 3.56% to 6,813.34, its fourth consecutive gain, retaking the 6,800 line. The KOSDAQ barely participated, up 0.29% to 861.37.
- The trigger was overnight: US July CPI matched forecasts, boosting bets on a Fed hold in September and lifting Nvidia (+3.03%), Micron (+4.92%) and the Philadelphia Semiconductor Index (+2.49%).
- Foreign investors net bought roughly 1.49 trillion won (about $1.05 billion) of KOSPI shares as of the 3:30 p.m. snapshot, concentrated in large-cap chip names, while retail investors sold about 1.73 trillion won.
- The oddity: despite the equity surge, the won weakened roughly 0.8% to around 1,423 per dollar.
An American CPI print lit the fuse; Seoul supplied the powder
The story starts in New York. July US consumer inflation came in right on expectations, easing fears of further Fed tightening ahead of the September FOMC meeting. The broad US indexes were mixed — Dow -0.04%, S&P 500 +0.26%, Nasdaq +0.54% — but the semiconductor complex ran hard, with Nvidia up 3.03%, Micron up 4.92%, and AI-infrastructure names rallying alongside a 2.49% jump in the Philadelphia Semiconductor Index.
Seoul took the baton at the open. The KOSPI gapped up 194.88 points (+2.96%) to 6,773.92 at 9 a.m., pushed toward the 6,860 area by around 1 p.m., then gave back some ground into the close at 6,813.34 — still a 3.56% gain on top of yesterday’s 3.68% advance. The local accelerant was mounting expectation of large shareholder-return programs at Samsung Electronics and SK Hynix, the duo Korean media have collapsed into the portmanteau “Samjeonnix.”
One milestone: the combined market capitalization of Korea’s three equity venues (KOSPI, KOSDAQ, and KONEX, the small third board) reached 611.58 trillion won at midday — roughly $430 billion at today’s exchange rate — back above the 600 trillion mark for the first time in 15 sessions, since July 23.
A $1 billion handoff: foreigners bought what retail sold
The flow picture, taken from the 3:30 p.m. pre-close snapshot for the KOSPI market (final settled figures can differ slightly and are confirmed by the exchange the next morning): foreigners net bought 1.4891 trillion won (about $1.05 billion), institutions added a modest 262.2 billion won (about $180 million), and individual investors net sold 1.7271 trillion won (about $1.2 billion) — classic profit-taking into a vertical move.
The buying was unmistakably aimed at the chip complex. Based on intraday-range figures from mid-session reports (not confirmed closes): Samsung Electronics traded up 4.5-5.5% around the 267,000-won level; SK Hynix gained 5.9-7.3% into 1.6-million-won territory; component maker Samsung Electro-Mechanics ripped 9.9-12.1%; and SK Square, valued largely as a semiconductor holding company, rose 8.4-10.4%. Equipment suppliers Jusung Engineering (+4.9%) and Wonik IPS (+3.9%) followed, while Hyundai Motor and LG Energy Solution each added 2.4% as the large-cap tide lifted most big boats.
The fine print: a narrow rally and a weaker won
Underneath the headline number, this was a strikingly lopsided session. Large caps rose 4.03%, mid caps just 1.02%, and small caps actually fell 0.27%. By sector, electricals/electronics (+5.41%) and manufacturing (+4.28%) did the heavy lifting. The KOSDAQ sank as low as -0.52% around noon, dragged by telecom equipment (-2.74%) and software (-2.62%), with game developer Wemade down around 11.9%, before a late recovery pulled it to +0.29%. In short: the index soared, but the rally has not yet broadened.
Then there is the currency puzzle. Heavy foreign stock buying normally involves selling dollars for won, which supports the Korean currency. Today, both stocks and USD/KRW rose — the won weakened roughly 0.8% to around 1,423 per dollar. That is an unusual combination, and currency volatility is worth watching as a variable for whether foreign inflows persist. Add the speed of the move past 6,800, and some debate about overheating in large-cap chips is inevitable.
| Metric | Close / Level | Change |
|---|---|---|
| KOSPI | 6,813.34 | +3.56% |
| KOSDAQ | 861.37 | +0.29% |
| USD/KRW (intraday reading, not an official close) | around 1,423 | roughly +0.8% (won weaker) |
| Foreign net flow (KOSPI, 3:30 p.m. snapshot) | +1.4891 trillion won (~$1.05B) | Net buy |
| Institutional net flow (same snapshot) | +262.2 billion won | Net buy |
| Individual net flow (same snapshot) | -1.7271 trillion won | Net sell |
| Combined market cap (KOSPI+KOSDAQ+KONEX, midday) | 611.58 trillion won (~$430B) | Above 600T for first time in 15 sessions |
What to watch next
- Settled investor-flow data tomorrow morning from official KRX sources — today’s flow figures are a 3:30 p.m. snapshot and may be revised.
- Whether the rally broadens: small caps fell today, so watch for rotation into mid and small caps as a health check.
- USD/KRW: continued won weakness alongside foreign equity buying would be an unusual mix worth monitoring.
- Any concrete shareholder-return announcements from Samsung Electronics or SK Hynix — expectations, not confirmed plans, powered part of today’s move.
- Fed messaging into the September FOMC after the in-line July CPI.
FAQ
Why did the KOSPI rise more than 3% today?
Three reasons stacked: US July CPI came in as expected, easing Fed-tightening fears; US chip stocks rallied hard overnight; and expectations of major shareholder returns at Samsung Electronics and SK Hynix drew concentrated foreign buying into Korean semiconductor large caps.
Why is the Korean won falling while stocks are surging?
It is an atypical pairing. Foreign equity inflows usually support the won, yet USD/KRW rose roughly 0.8% to around 1,423 today. The session data does not pin down a single cause, but the divergence is flagged as a risk factor for the durability of foreign buying.
How much did foreign investors buy?
About 1.49 trillion won (roughly $1.05 billion) net in the KOSPI market as of the 3:30 p.m. pre-close snapshot, focused on large-cap semiconductor names. Final settled figures are confirmed the next morning.
Is this rally broad-based?
Not yet. Large caps gained 4.03% while small caps fell 0.27%, and the KOSDAQ added just 0.29%. The advance is concentrated in a handful of semiconductor heavyweights — a fact to weigh when judging its staying power, though we make no buy or sell calls here.
Disclaimer: This is an information and analysis publication, not investment advice. See our Methodology for data sources, standards, and our corrections policy.