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Chips lift KOSPI while KOSDAQ slides — two markets, two stories on a volatile Friday morning — Korea Market Midday, Aug 21, 2026

The Silmari
A daily data newsletter on the Korean stock market — silmari, ‘a clue: the loose end that unravels the knot’
③ Midday 12:002026.08.21 Fri · No. 18Sentiment gauge: “Unease” — composite score 0.986; 20-day realized volatility at 5.97% (93rd percentile, confirmed today); leverage ETF share at 13.77% of market turnover (99th percentile, confirmed today). Credit balance and short-surge components are carrying prior-day values (T+1/T+2 publication lag) and have not been updated for today’s session.
③ Midday · published 12:00 KST · session in progress
01 · VerdictRegular session confirmed 15:30 KST

12:00verdict at this hour

Chips lift KOSPI while KOSDAQ slides — two markets, two stories on a volatile Friday morning

The KOSPI closed up 0.42% at 6,881.59 on Friday, August 21 (2026), as SK hynix and Samsung Electronics powered a semiconductor-led advance even as most other sectors retreated; the KOSDAQ, by contrast, shed 5.29% to close at 796.37, the index’s intraday path tracing a steady drift lower from the opening bell through the late morning.The divergence was sharp: the KOSPI’s intraday range spanned 173.67 points (2.58% high-to-low), with a session low of 6,742.44 and a session high of 6,916.11, while the KOSDAQ’s 28.45-point range (3.58%) was set almost entirely in decline, with the high of 824.05 printed at the open and the low of 795.60 touched near 11:05.

Key points
01Prediction scorecard (intraday, Provisional (Intraday) Flow DataInvestor net-buying figures collected before KRX’s official end-of-day reconciliation, typically published between 18:00 and 20:00 KST; the intraday read can differ from the confirmed figure.The Silmari flags provisional data explicitly so readers do not treat midday flow snapshots as final settlement figures.): P1 (KOSPI, up +0.3~+1.5%) hit — actual close +0.42%. P2 (KOSDAQ, range -0.5~+0.5%) missed badly — actual close -5.29%. Final verdicts in the evening edition.
02Japan (as of JST 11:30 close): The Nikkei 225 stood at 66,008.45, down 0.31% from Thursday’s close of 66,216.79 — this is the pre-lunch close value, as the Tokyo market was in its midday recess (11:30–12:30 JST) at time of collection.
03Chip divergence inside the KOSPI: SK hynix (+3.90%, ₩4,262.5bn turnover) and Samsung Electronics (+3.14%, ₩3,749.3bn) pulled the index up, while Samsung Electro-Mechanics slid 5.73% and Kakao dropped 11.11% — illustrating how narrow today’s KOSPI advance is beneath the surface.
04Foreign Net PurchaseThe difference between total shares bought and total shares sold by a given investor group over a period; a positive figure means that group put more money in than it took out.Tracking which group — foreigners, institutions, or retail — is the net buyer or net seller on any given day is the standard first read on demand pressure in the Korean market. in KOSPI, retail selling: As of the midday provisional read (collected 11:52 KST), foreigners were net buyers of ₩374.7bn on KOSPI today; retail investors were net sellers of ₩656.3bn — institutional investors (combined) were net sellers of ₩270.2bn. These are provisional figures; confirmed data is published by KRX after 18:00 KST.
02 · SnapshotUntil 12:00 · Korea Investment & Securities Index 5-min (High/Low based on 5-min close)(May vary slightly from exchange official figures)

12:00Snapshot

A window that records the market at that hour, like a photograph

Foreigners buy ₩374.7bn net on KOSPI; retail investors and institutions both sell as chip gains mask broad-market weakness

KOSPI at 12:00Open6,759.95· High6,935.01(11:55) · Low6,767.34(09:05) · as of 12:006,925.39
KOSDAQ at 12:00Open824.05· High815.82(09:00) · Low795.69(11:00) · as of 12:00800.04
03 · Top 10 checkpointsKorea Investment & Securities 5-min bar · Until 12:00

Top by trading value10— snapshot

A window on how the top trading-value names have moved up to this hour

SK hynix and Samsung Electronics dominate KOSPI turnover as chips absorb the day’s buying interest

Through approximately 11:52 KST, SK hynix printed ₩4,261.4bn in KOSPI turnover — the session’s heaviest — with the stock reaching an intraday high of ₩1,773,000 at 09:52 before easing; Samsung Electronics followed at ₩3,748.2bn, touching ₩281,500 at 10:50 before consolidating.Samsung Electronics preferred shares ranked third on KOSPI by turnover at ₩1,170.5bn, posting the session’s widest percentage move among the turnover leaders (+8.26%), while Samsung Electro-Mechanics generated ₩504.3bn despite falling 5.73% — heavy two-way flow in the semiconductor-component group was a feature of the morning.

Top 10 by Trading Value — Prior Close · Open · Gap · Values as of 12:00 (may differ slightly from exchange official figures)
StockPrior closeOpenGapHigh (time)12:00 Current PriceChangeLow (time)
Samsung Electronics271,000267,000−1.48%281,500 (10:50)280,500 (12:00)+3.51%266,000 (09:03)
SK hynix1,691,0001,675,000−0.95%1,773,000 (09:52)1,767,000 (12:00)+4.49%1,671,000 (09:01)
Samsung Electronics (Pref.)191,200190,100−0.58%208,500 (10:50)207,000 (12:00)+8.26%190,200 (09:01)
Samsung Electro-Mechanics1,396,0001,345,000−3.65%1,348,000 (09:11)1,328,000 (12:00)−4.87%1,306,000 (10:10)
SK Square1,123,0001,096,000−2.40%1,141,000 (09:48)1,128,000 (12:00)+0.45%1,079,000 (09:01)
Kumho E&C15,65015,650+0.00%18,200 (09:25)15,890 (12:00)+1.53%14,810 (09:02)
Kakao38,70038,150−1.42%38,650 (09:04)34,250 (12:00)−11.50%33,600 (10:52)
Samsung Life Insurance296,989291,500−1.85%320,000 (11:22)317,500 (12:00)287,000 (09:01)
SK Securities2,8102,920+3.91%3,555 (09:05)3,015 (12:00)+7.30%2,965 (11:02)
Kumho Electric7,4608,000+7.24%9,690 (09:24)8,840 (12:00)+18.50%7,810 (09:02)

Kakao’s intraday path stood out for the opposite reason: the stock opened at ₩38,600 and reached its session high of ₩38,750 at 09:00, then declined steadily to a low of ₩33,600 at 10:52, generating ₩165.9bn in turnover on sustained selling pressure throughout the morning.Kumho Construction was the turnover outlier in a different sense: ₩408.2bn changed hands in a stock that swung from ₩14,810 (low, 09:02) to ₩18,200 (high, 09:25) before retreating — the 22.9% intraday spread reflects the short-selling surge flagged in the prior session’s data (surge ×5.1 recorded on August 13).

04 · Up · DownReason labels: [News] confirmed · [Pattern] inferred

Gainers5· Decliners5— snapshot

A window on the biggest gainers and decliners, and the reasons behind them

KOSPI closes up +0.42% as chip giants surge; KOSDAQ drops 5.29% on broad-based selling across biotech and defense names.

On the KOSPI, gainers were concentrated in semiconductors and financials: Samsung Electronics preferred shares surged 8.26% with ₩1,171.2bn in turnover, SK hynix rose 3.96%, and the financial complex (Hana Financial Group +3.81%, Shinhan Financial +2.67%, KB Financial +1.59%) added to breadth.Decliners were broader and deeper: Kakao fell 11.24%, LIG Defence & Aerospace dropped 11.05%, OCI Holdings shed 8.79%, Hanwha Solutions fell 8.66%, and GS Engineering & Construction lost 8.85% — defense, construction, and clean-energy names bore the brunt of selling.On the KOSDAQ, the picture was almost uniformly red: Algeonomics fell 17.23%, Kido Industries dropped 15.49%, Ingenium Therapeutics (Reg.S) lost 11.95%, and Simtec slid 11.14%; Alteogen gave back 8.25% with ₩79.3bn in turnover — the biotech and semiconductor-equipment groups that had outperformed in recent sessions were among the day’s sharpest losers.

Gainers —12:00as measured at this hour
Komico * (KOSDAQ)+27.06%· turnover ₩43.8bn
Coocon (KOSDAQ)+23.17%· turnover ₩17.9bn
Uri Technology Investment * (KOSDAQ)+19.96%· turnover ₩137.7bn
IndiEF+18.26%· turnover ₩19.2bn
Galaxia Moneytree (KOSDAQ)+12.61%· turnover ₩85.5bn
Losers —12:00as measured at this hour
Gidosan Industries * (KOSDAQ)−34.58%· turnover ₩213.4bn
Alginomics * (KOSDAQ)−18.18%· turnover ₩24.4bn
Enchem (KOSDAQ)−15.98%· turnover ₩14.7bn
Ingenia Therapeutics (Reg.S) * (KOSDAQ)−13.97%· turnover ₩415.3bn
Gigavis (KOSDAQ)−13.40%· turnover ₩17.9bn
Historical contextSelection: turnover of ₩10bn or more · machine ranking by percentage change.
Sources: Korea Exchange · NXT · own measurements · regular session confirmed 15:30 KST · The Silmari editorial desk.
This edition organises and explains publicly available market data. It is not investment advice. Predictions and their scores are preserved without revision — the judgement is yours.