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KOSPI Gaps Down Hard at Open, Stages Mid-Morning Rally, Then Fades Into Lunch — Korea Market Midday, Aug 19, 2026

The KOSPI opened Wednesday, August 19 (2026) at 6,528.77, sold off sharply to an intraday low of 6,400.81 at 09:17, then clawed back to a session high of 6,614.39 at 10:22 — a swing of 213.58 points, or 3.34% of range — before fading to the 6,490s by the noon snapshot.The KOSDAQ followed a divergent

The Silmari
A daily data newsletter on the Korean stock market — silmari, ‘a clue: the loose end that unravels the knot’
③ Midday 12:002026.08.19 Wed · No. 16Sentiment gauge: Anxious (stage 2 of 4) — composite score 1.062. Confirmed inputs today: 20-day realized volatility at 5.86 (93rd percentile, expanding window); leverage ETF share at 14.68% (99th percentile); no program-buy-on-down trigger today. Credit and short-surge readings are lagged (last confirmed August 14 and August 12 respectively).
③ Midday · published 12:00 KST · session in progress
01 · Verdict★Preliminary — Source correction in progress (FDR 6536.85 / Naver 6491.74)

12:00verdict at this hour

KOSPI Gaps Down Hard at Open, Stages Mid-Morning Rally, Then Fades Into Lunch

The KOSPI opened Wednesday, August 19 (2026) at 6,528.77, sold off sharply to an intraday low of 6,400.81 at 09:17, then clawed back to a session high of 6,614.39 at 10:22 — a swing of 213.58 points, or 3.34% of range — before fading to the 6,490s by the noon snapshot.The KOSDAQ followed a divergent script: after dipping briefly to 804.02 at 09:01, the junior market recovered firmly, spending most of the late morning above 830 — a markedly shallower drawdown than the large-cap board, consistent with domestic-oriented names holding better in a session dominated by semiconductor selling.

Key points
01Morning forecast — partial miss. The 07:30 call (P1) projected KOSPI −1.5% to −3.0%; actual close is −4.85%, overshooting the band — verdict (direction correct, magnitude underestimated). P2 called KOSDAQ −2.0% to −3.5%; actual close is −0.38% — verdict (direction wrong). Both are intraday provisional scores; final scores publish in the evening edition.
02Nikkei 225 morning session (JST 11:30 bar): 65,715.90, −2.59% vs. prior close of 67,460.73. Japan’s market entered its midday break with losses broadly in line with regional pressure; the figure reflects the JST 11:30 bar — the last print before the lunch recess (11:30–12:30 JST). The TOPIX proxy ETF (1306.T) stood at 419.40, −2.69% (proxy, not the index itself).
03Semiconductors lead the decline: SK hynix traded to an intraday low of 1,501,000 won at 09:16 before recovering; Samsung Electronics touched 247,000 at 09:27. Sector flow data for today are not yet collected (per-stock foreign net figures marked as uncollected in the data). The overnight Philadelphia Semiconductor IndexA U.S. equity index tracking 30 companies involved in the design, distribution, manufacture, and sale of semiconductors.Because Korean chipmakers such as SK hynix and Samsung Electronics derive a large share of revenue from global semiconductor cycles, the SOX overnight move is a widely-watched leading indicator for Korean chip stocks the following morning. closed at 11,992.46, down 4.98% as of August 18 (2026).
04Foreigners Net SaleThe mirror of net purchase: total sells exceed total buys, leaving a negative balance for the period.On days when foreigners are large net sellers and retail investors are the offsetting buyer, the dynamic often reflects different time-horizon assumptions between the two groups. KOSPI; retail buying: As of the 11:52 snapshot (provisional, pre-final), foreign investors are net sellers of −₩1.89tn on KOSPI today, while retail investors are net buyers of +₩2.87tn. The National Pension Service is a modest net buyer at +₩108.8bn. These figures are provisional; the confirmed print is expected by this evening.
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

Broad selling at the open gives way to a two-hour rally, then a partial fade — the KOSPI’s intraday range reaches 213.58 points (3.34%) as of the noon snapshot.

KOSPI at 12:00Open6,528.77· High6,593.30(10:15) · Low6,422.65(09:15) · as of 11:556,490.03
KOSDAQ at 12:00Open810.08· High840.44(10:05) · Low805.49(09:10) · as of 11:55832.76
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 turnover at ₩3.30tn and ₩2.90tn respectively, both off their morning lows by the noon snapshot.

By the 11:52 intraday snapshot, SK hynix had traded ₩3,301.7bn in turnover — the heaviest on the KOSPI — having swung from a low of 1,501,000 won at 09:16 to a high of 1,559,000 at 10:20, a range of ₩58,000 per share.Samsung Electronics, second in turnover at ₩2,896.4bn, similarly bottomed at 247,000 won at 09:27 before recovering to 254,500 at 10:15; Samsung Electro-Mechanics ranked third at ₩669.2bn, with a range of 81,000 won between its session low of 1,350,000 and high of 1,431,000.

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)
SK hynix1,662,0001,545,000−7.04%1,559,000 (10:20)1,521,000 (12:00)−8.48%1,501,000 (09:16)
Samsung Electronics268,500251,500−6.33%254,500 (10:15)249,250 (12:00)−7.17%247,000 (09:27)
Samsung Electro-Mechanics1,440,0001,357,000−5.76%1,431,000 (10:20)1,370,000 (12:00)−4.86%1,351,000 (09:04)
SK Square1,135,0001,030,000−9.25%1,042,000 (10:22)1,011,000 (12:00)−10.93%993,000 (09:26)
Hanwha Aerospace1,146,0001,255,000+9.51%1,255,000 (09:02)1,171,000 (12:00)+2.18%1,146,000 (09:01)
Samsung Electronics (Pref.)188,300176,400−6.32%178,700 (10:23)174,600 (12:00)−7.28%172,700 (09:05)
SK eternix58,50056,400−3.59%60,700 (09:10)59,100 (12:00)+1.03%55,000 (09:16)
Samsung SDI488,000467,500−4.20%501,000 (10:21)489,000 (12:00)+0.20%469,000 (09:01)
Hyundai Motor435,000416,000−4.37%422,500 (10:30)413,000 (12:00)−5.06%406,500 (09:27)
Isu Petasys102,90099,900−2.92%110,800 (10:15)106,800 (12:00)+3.79%98,400 (09:01)

Hanwha Aerospace showed an atypical intraday path: its session high of 1,255,000 won came at the open (09:02), and it spent the morning drifting lower to a low of 1,150,000 at 09:45 before partially recovering — an open-to-low pattern that contrasts with the broad market’s V-shape recovery in the 09:15–10:22 window.Isu Petasys, tenth in KOSPI turnover at ₩111.6bn, opened at 99,200 won and reached its high of 110,800 at 10:15, holding gains into the noon hour — one of the few KOSPI names to sustain its morning bounce.

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

Gainers5· Decliners5— snapshot

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

Chip giants lead broad declines as the KOSPI closes at 6,536.85, down 4.85% on the day, while defense and construction names partially offset losses.

On the KOSPI, the session’s gainers are concentrated in defense, construction, and select energy names: Hanwha Aerospace rose +2.97%, Hyundai Engineering & Construction +4.90%, HD Hyundai Energy Solutions +7.54%, and Isu Petasys +3.98%.Declines are concentrated in semiconductors and their holding companies: SK Square fell −10.75%, Samsung Life −9.18%, SK hynix −8.18%, and Samsung Electronics −6.89%.On the KOSDAQ, the pattern is more mixed: Ananti surged +21.78% and Bioneer +29.99%, while the KOSDAQ’s by-turnover leader Ingenio Therapeutics (Reg.S) dropped −6.06%; HPSP gained +8.56% and was the second-heaviest traded name on the junior board at ₩165.4bn turnover.

Gainers —12:00as measured at this hour
Bionia * (KOSDAQ)+29.99%· turnover ₩10.9bn
Hwashin Precision * (KOSDAQ)+29.79%· turnover ₩51.0bn
Bivoxen Pharma * (KOSDAQ)+26.56%· turnover ₩22.0bn
Ananti * (KOSDAQ)+21.33%· turnover ₩159.4bn
DaeAITAI * (KOSDAQ)+16.09%· turnover ₩33.3bn
Losers —12:00as measured at this hour
DN Automotive−10.99%· turnover ₩18.4bn
SK Square−10.75%· turnover ₩354.5bn
Samsung Life Insurance−9.34%· turnover ₩56.9bn
Kumho E&C−8.39%· turnover ₩30.6bn
SK hynix−8.30%· turnover ₩3308.3bn
Historical contextSelection: turnover of ₩10bn or more · machine ranking by percentage change.
Source: Korea Exchange · NXT · Actual measurement · Reference ★Preliminary — Source correction in progress (FDR 6536.85 / Naver 6491.74) · Compiled by Silmari Editorial Team.
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.