Today’s Verdict
KOSPI −5.8%: Bond Shock Swamps Semiconductor Giants
The KOSPI closed at 6,471.17 on Wednesday, August 19 (2026), shedding 5.8% as a surge in long-end U.S. Treasury yields — the 30-year briefly crossing 5.33% — amplified an already-weak overnight Philadelphia Semiconductor IndexA U.S. equity index tracking the 30 largest semiconductor design and manufacturing companies; widely used as a leading proxy for global chip demand.Korean semiconductor giants SK hynix and Samsung Electronics track SOX moves closely — a large SOX swing the prior night often sets the direction for KOSPI the next morning. reading of −4.98% into a broad rout led by SK hynix (−9.75%) and Samsung Electronics (−7.82%).KOSDAQ closed at 824.46, off only 1.17%, as defensive and bio names absorbed less foreign pressure — foreigners were effectively flat on KOSDAQ (net +₩14.7bn) while selling ₩3.47tn on KOSPI.
| Index | Close | Today | 1 week ago 08/12 | 1 month ago 07/20 | 1 quarter ago 05/20 | 6 months ago 02/13 | 1 year ago 08/19 |
|---|---|---|---|---|---|---|---|
| KOSPI | 6,471.17 | −5.80% | −1.64% | −0.69% | −10.23% | +17.51% | +105.33% |
| KOSDAQ | 824.46 | −1.17% | −4.01% | +9.98% | −21.93% | −25.46% | +4.63% |
Did our calls hold?
A window grading the morning’s calls against what actually happened
Both calls got direction right but underestimated KOSPI’s drop at 5.8% and overestimated KOSDAQ’s at 1.17%.
Both morning calls missed on magnitude: KOSPI was projected to fall 1.5%–3.0% but actually fell 5.8%; KOSDAQ was projected to fall 2.0%–3.5% but fell only 1.17%.The directional call on both markets was correct (both verdicts: △), but the bond-yield shock — the 30-year crossing 5.33% during the Korean session — was not in the morning model, and the KOSDAQ’s bio/defensive cushion was underestimated.
No intraday or sector-level predictions were made this morning; the two market-level calls above are the full prediction record for Wednesday, August 19 (2026).
The day’s path
A window retracing where the index travelled from open to close
KOSPI opened at 6,500.88, briefly touched 6,614.39 by 10:22, then declined in two waves to close at 6,471.17.
Who bought and who sold —4 investorgroups ×4periods
A window on how much foreign investors, retail investors, investment firms and pension funds each bought and sold
Foreigners dumped a net ₩3.47tn on KOSPI as the index closed at 6,471.17, off 5.8%.
| Investor group | Today | 1 week 08.12~08.19 | 1 month 07.20~08.19 | Quarter |
|---|---|---|---|---|
| Foreign investors | −₩3.47tn | +₩4.60tn | −₩495.5bn | −₩75.99tn |
| Retail investors | +₩4.64tn | −₩2.54tn | +₩1.25tn | +₩61.73tn |
| Pension funds | +₩73.1bn | −₩60.6bn | +₩779.1bn | −₩2.61tn |
| Investment firms | −₩1.36tn | −₩2.06tn | −₩2.63tn | +₩16.48tn |
Foreign investors net sold ₩3.47tn on KOSPI today — the single largest outflow among investor categories.In the futures market, foreigners also net sold 331 contracts on Wednesday, August 19 (2026), after being net buyers of 808 contracts the prior session — a one-day reversal that aligned with the cash-market direction.
Retail investors net bought ₩4.64tn on KOSPI, absorbing most of the foreign selling.In the 2026 regime (152 sessions), the same-day correlation between foreign net buying and retail net buying runs at −0.849 — today’s pattern is entirely consistent with that structural opposition.
The National Pension Service was a marginal net buyer at ₩73.1bn on KOSPI — a stabilizing posture on a down day, but small relative to foreign outflows.Securities firms net sold ₩1.36tn on KOSPI; in the futures market, institutions net bought 2,175 contracts, with the non-financial-investment sub-group adding 7,108 contracts while financial investment firms sold 5,100 — the two sub-groups moved in opposite directions.
On KOSDAQ the picture was nearly flat: foreigners net bought ₩14.7bn, securities firms net bought ₩57.9bn, and retail net sold ₩66.4bn — all small numbers relative to KOSPI.The contrast with KOSPI’s ₩3.47tn foreign outflow underscores that the sell-off was concentrated in large-cap semiconductor names listed on KOSPI, not in the broader market.
Over the past quarter (May 19 – August 19, 2026), foreigners have net sold ₩75.99tn on KOSPI while retail has net bought ₩61.73tn — a sustained structural transfer.Securities firms have been net buyers of ₩16.48tn on KOSPI over the same period, partially offsetting foreign selling alongside retail, while the pension service has net sold ₩2.61tn on a quarterly basis.
Silmari Fear Gauge — past and present
A window measuring market anxiety through volatility, margin lending and short selling
The sentiment gauge held at 0.963 — “Anxious” stage — on a day when realized volatility hit the 93rd percentile.
The sentiment gauge closed Wednesday, August 19 (2026) at 0.963, placing it in the “Anxious” stage (expanding-window percentile between 65 and 90).Of the components with confirmed today’s readings: realized volatility (vol20) was 5.91 — 93rd percentile; leverage ETF share was 13.31% — 97th percentile; panic-buying-on-down-days (pbuy_down) was 0.0 — 70th percentile; and the no-trigger streak was 0 — 86th percentile.
The credit balance (as of August 18, 2026) stood at 3.6 and the margin ratio at 0.7 — both T+1 lagged figures from the Korea Financial Investment Association.The short-surge sub-signal (value 12.1, as of August 13, 2026) is T+2 lagged from the exchange’s short-interest disclosure; today’s short position data will not be confirmed until August 21 (2026).
| Measure | Today’s value | Basis | Where today sits |
|---|---|---|---|
| Retail buying intensity on down days | 0.0 | Current regime (2026) percentile | 70(top 30%) |
| KOSPI 20-day realised volatility | 5.91 | Current regime (2026) percentile | 93(top 7%) |
| Consecutive no-trigger down days | 0.0 | Current regime (2026) percentile | 86(top 14%) |
| Leveraged-ETF share of turnover | 13.31 | Current regime (2026) percentile | 97(top 3%) |
Today qualifies as a trigger day: the 30-year U.S. Treasury yield crossing 5.33% and the SOX decline of 4.98% provided identifiable external catalysts for the sell-off.The no-trigger streak component therefore reset to 0, meaning no additional anxiety accumulation from that sub-signal — the spike in the overall score came from the volatility and leverage-share components, not from a prolonged streak of unexplained declines.
On days when sentiment is “Anxious” and a clear external trigger is present, the subsequent path depends heavily on whether the trigger resolves — the gauge itself does not distinguish between a one-day shock and the start of a prolonged drawdown.The judgment is each reader’s own.
The sentiment gauge is a weighted composite of eight sub-signals: (1) five-day change in credit balances (weight 13.5%), (2) margin loan ratio (18%), (3) panic buying on down days (9%), (4) short-surge indicator (18%), (5) realized 20-day volatility (22.5%), (6) no-trigger-decline streak (9%), and (7) leverage ETF share of turnover (10%) — each normalized to an expanding-window percentile to prevent look-ahead bias; a planned eighth signal based on news sentiment is excluded from the composite due to the absence of a historical news archive.
The judgement is yours.
Short sellingSelling borrowed shares first, betting the price will fall.A rising balance means more money is betting on a decline.balance — the pattern of surges
A window on the stocks whose short balance rose or fell, and what happened afterwards
Short-selling activity flagged last week in SK hynix now sits inside a current-regime (2026) pattern where 5-day returns averaged −0.43% in 114 comparable episodes.
The most recent short-surge events in the data involve SK hynix (August 11 and 12, 2026) and Simtech (August 10, 2026).Across 381 short-surge events since 2018 (defined as short interest at least doubling in five sessions with a base of 50,000+ shares), the 5-day return in the current 2026 regime averaged −0.43% across 114 events, with stocks declining in 51% of cases — compared with the regime baseline of +2.75%, yielding an excess return of −3.18 percentage points.For SK hynix specifically, the August 11 surge (×12.1) produced a 1-day return of +5.54% and 3-day return of +15.44%; the August 12 surge (×19.1) produced a 1-day return of +5.92% and 3-day of +10.51% — both resolved upward in the short run, though today’s −9.75% drop comes after those rebounds, suggesting the short interest may have reasserted pressure.
Where the money moved —12sectors
A window on where money moved from and to, by sector
Semiconductors fell 6.11% as a sector while construction and infrastructure rose 2.56%, the sharpest intra-day divergence recorded today.
| Sector | Today | Flows | Relative (1w) | Leaders |
|---|---|---|---|---|
| Semiconductors | −6.11% | Selling | +1.40%p | Samsung Electronics−7.82%· SK hynix−9.75%· SK Square−11.54%· Samsung Electro-Mechanics−3.68%· Jusung Engineering−4.29% |
| AI & Software | −2.89% | Buying | −4.80%p | NAVER −4.15%· Kakao−2.22%· DearU−2.29% |
| Power & Electrical | −3.03% | Buying | −2.50%p | Doosan Enerbility−2.18% · LS ELECTRIC −3.35%· HYOSUNG Heavy Industries−2.55%· HD Hyundai Electric−4.20%· Gaon Cable−2.89% |
| Electronics & Components | −2.31% | Selling | +8.90%p | Samsung Electronics (Pref.)−7.75%· LG Energy Solution+1.85%· Samsung SDI−0.20%· LG Electronics−3.13% |
| Autos | −3.21% | Selling | +0.70%p | Hyundai Motor−4.83%· Kia−3.06%· Hyundai Mobis−1.74% |
| Defense & Aerospace | −0.08% | Selling | +5.20%p | Hanwha Aerospace+2.71%· LIG Defense & Aerospace+0.13%· Korea Aerospace Industries (KAI)−3.07% |
| Shipbuilding & Shipping | −3.09% | Buying | −3.00%p | Hanwha Ocean−3.08%· HD KSOE (Korea Shipbuilding & Offshore Engineering)−2.00% · HMM −4.19% |
| Financials | −2.41% | Selling | −2.10%p | KB Financial Group−1.25%· Shinhan Financial Group−1.41%· Hana Financial Group−2.45%· Mirae Asset Securities−4.54% |
| Bio & Healthcare | −1.04% | Buying | −6.00%p | Samsung Biologics+0.85%· Celltrion−0.72%· Alteogen+1.85%· Kolon TissueGene−6.16% |
| Construction & Infrastructure | +2.56% | Selling | +1.80%p | Hyundai E&C+5.81%· Daewoo E&C+0.17%· DL E&C+1.70% |
| Energy & Chemicals | −2.13% | — | +5.10%p | SK Innovation−1.98%· LG Chem−1.66% · S-Oil −1.30%· Lotte Chemical−3.59% |
| Consumer & Entertainment | −0.46% | Selling | −6.20%p | SK Telecom−1.80%· HYBE+0.23%· CJ CheilJedang−1.80% · JYP Ent. +1.52% |
The stocks that moved the market — top by turnover10
A window on which investor groups backed the most heavily traded stocks
SK hynix and Samsung Electronics together accounted for ₩1.21tn of KOSPI turnover as both shed more than 7%.
SK hynix (₩6,408.3bn turnover) and Samsung Electronics (₩5,682.9bn) together accounted for the bulk of KOSPI activity, with foreign investors selling ₩1,817.6bn in SK hynix and ₩1,037.2bn in Samsung Electronics alone.The only gainer in the KOSPI top-ten by turnover was Hanwha Aerospace, which rose +2.71% on ₩486.8bn of volume despite foreigners net selling ₩92.6bn of the stock — domestic institutional and retail buying absorbed the foreign supply.
| Stock | Close | Change | Turnover | Foreign investors | Institutions | Investment firms | Pension funds | Retail investors |
|---|---|---|---|---|---|---|---|---|
| SK hynix | ₩1,500,000 | −9.75% | ₩6.41tn | −₩1.83tn | −₩471.9bn | −₩567.8bn | +₩28.7bn | +₩2.22tn |
| Samsung Electronics | ₩247,500 | −7.82% | ₩5.68tn | −₩1.04tn | −₩733.5bn | −₩665.1bn | +₩3.3bn | +₩1.69tn |
| Samsung Electro-Mechanics | ₩1,387,000 | −3.68% | ₩1.02tn | −₩149.9bn | +₩1.2bn | +₩18.4bn | −₩4.5bn | +₩140.5bn |
| SK Square | ₩1,004,000 | −11.54% | ₩635.5bn | −₩216.5bn | −₩23.3bn | −₩2.1bn | −₩6.4bn | +₩233.4bn |
| Samsung Electronics (Pref.) | ₩173,700 | −7.75% | ₩541.6bn | −₩133.8bn | −₩41.6bn | +₩2.9bn | −₩9.8bn | +₩166.3bn |
| Hanwha Aerospace | ₩1,177,000 | +2.71% | ₩486.8bn | −₩92.8bn | +₩55.4bn | −₩1.3bn | +₩43.7bn | +₩36.8bn |
| SK eternix | ₩57,800 | −1.20% | ₩229.9bn | −₩4.3bn | +₩13.5bn | +₩5.6bn | +₩0.0bn | −₩8.6bn |
| Hyundai Motor | ₩414,000 | −4.83% | ₩228.2bn | −₩22.6bn | −₩23.1bn | −₩11.7bn | −₩3.5bn | +₩44.5bn |
| Samsung SDI | ₩487,000 | −0.20% | ₩192.5bn | +₩8.0bn | −₩4.7bn | −₩1.9bn | −₩7.1bn | −₩3.1bn |
| LG Electronics | ₩201,500 | −3.13% | ₩174.1bn | +₩2.3bn | −₩15.6bn | −₩8.6bn | +₩6.4bn | +₩12.7bn |
Gainers5· Decliners5 — KOSPI & KOSDAQ
A window on the biggest gainers and decliners, and the reasons behind them
Only 171 KOSPI issues advanced versus 703 decliners, yielding an ADR of 0.24 — the breadth of a broad-market rout.
On KOSPI, 171 issues rose, 703 fell, and 68 were unchanged — an advance-decline ratio of 0.24, well below the prior comparable session (August 14: ADR 3.32 on a strong up day).On KOSDAQ, 396 issues rose against 1,275 declines (ADR 0.31), confirming a market-wide down day despite the index’s relatively mild −1.17% close; the top-ten concentration on KOSPI was 67.5% of total KOSPI turnover — the day’s pain was heavily concentrated in the largest names.
The SilmariDecouplingWhen two markets that used to move together break apart and move separately.The wider the gap, the less any single index can tell you about the market.Gauge
A window on the pattern in the KOSPI–KOSDAQ decoupling
KOSDAQ closed at 824.46, off 1.17% — a far shallower loss than KOSPI’s 5.8% decline.
KOSDAQ’s −1.17% close against KOSPI’s −5.8% represents a gap of 4.63 percentage points — unusually wide, reflecting the fact that the day’s damage was concentrated in large-cap semiconductor names that weigh heavily on KOSPI but less so on KOSDAQ.KOSDAQ also traced a different intraday shape: it touched its low of 804.02 at 09:01, recovered to a high of 840.50 by 10:10, and then drifted gradually lower into the close — suggesting early risk-off selling was quickly absorbed by buyers who rotated from semiconductor names into KOSDAQ-listed bio and mid-cap growth stocks.
Semiconductors → defensives, and back — by regime
A window on the pattern in sector rotation — money circulating from one sector to another
Construction and infrastructure rose 2.56% while semiconductors fell 6.11%, meeting the quantitative definition of a defensive rotation day.
| Regime | Reversion rate · sample |
|---|---|
| ① Old order (2018–24) | Average−0.84%· rose 45% of the time · 69 past cases |
| ② Transition (2025) | Average+1.70%· rose 71% of the time · 17 past cases |
| ③ Current regime (2026–) | Average+2.05%· Up 69% · 32 times previously |
A day when semiconductors (the average of SK hynix and Samsung Electronics) fall 2.0% or more while defensives (bio, food & beverage) outperform by 2.0%p or more = rotation (a flight)
Today qualifies as a rotation day under the stated definition: the semiconductor proxy (SK hynix −9.75%, Samsung Electronics −7.82%, average approximately −8.8%) fell well beyond the −2.0% threshold, and the construction/infrastructure sector rose +2.56% — more than 2.0 percentage points above the semiconductor proxy’s move.In the current 2026 regime, the 32 past rotation days produced an average 3-day KOSPI return of +2.05% with an up-probability of 69%; over the most recent six months (28 events), the average was +1.71% with 64% up — past rates are not a guarantee.
The night makes the morning —American Depositary Receipt (ADR)A twin of a Korean stock, listed on a U.S. exchange.It prints overnight, showing how U.S. investors price Korean stocks before Seoul opens.crash detection
A window on how U.S.-listed Korean stocks moved overnight
The pre-crash signal score came in at 3 of 4 on Wednesday, August 19 (2026), with ADR and short-surge sub-signals both lit.
The pre-crash signal score was 3 out of a possible 4 on Wednesday, August 19 (2026): the ADR sub-signal was lit (reference date: July 28, 2026 U.S. session, ADR −16.7%), the short-surge sub-signal was lit (short-interest data as of August 13, 2026), and the selling-acceleration and sentiment-90+ sub-signals were not triggered.A score of 3 indicates elevated caution, but the system does not specify a threshold at which a crash is called as certain — the score is a summary of concurrent warning signals, not a prediction; and the signal components carry different reference dates, so they do not all describe the same moment in time.
Tonight — the U.S. session about to open
U.S. markets open with S&P 500 futures at 7,713.25 (−0.37%) and FOMC minutes due tonight.
Korea–U.S. mutual following — overnight grading
A window on which market followed which
SOX fell 4.98% in the prior U.S. session and KOSPI followed with a 5.8% decline — a textbook Korea-follows-America day.
The prior U.S. session saw SOX fall 4.98%, Nasdaq fall 1.33%, and S&P 500 fall 0.69% — all negative, with the semiconductor index carrying the largest loss.KOSPI then fell 5.8% — exceeding even the SOX decline — consistent with the Korea-follows-America pattern; the Nikkei 225 on Wednesday also fell 3.16% (full-day) to 65,326.42, confirming a pan-Asian response to the U.S. yield and semiconductor shock.
Year-to-date in 2026 (139 sessions), Korea followed the prior night’s U.S. SOX direction in 39 sessions, the U.S. followed Korea in 30 sessions, both moved together in 46 sessions, and neither tracked the other in 24 sessions.The bidirectional count of 46 is the largest single category, suggesting that on most active days the two markets reinforce each other — today’s Korea-follows-America pattern is the more common directional relationship when SOX moves exceed 0.5%.
Overnight SOX ↔ same-day KOSPI in the same direction (|SOX| ≥ 0.5%) = Korea following · same-day KOSPI ↔ that night’s SOX in the same direction (|KOSPI| ≥ 0.5%) = the U.S. following
The won — the signal is the speed of the move, not its direction
A window on the pressure the won-dollar rate puts on foreign flows
The won stood at ₩1,390 per dollar while the dollar index eased 0.29% to 99.36.
The won stood at ₩1,390 per dollar as of the latest strip reading, while the dollar index (DXY) eased 0.29% to 99.36 — a modest dollar softening that did not materially offset the risk-off pressure on Korean equities.The yen-won cross stood at ₩873.88 per 100 yen; the Nikkei’s 3.16% decline suggests yen safe-haven flows may be limited, keeping the yen-won rate relatively stable.
Rates — a weaker link than commonly assumed
A window on the burden rates and bonds place on equities
The 30-year U.S. Treasury yield briefly topped 5.33% — an event that preceded Wednesday’s Korean sell-off — before pulling back ahead of FOMC minutes.
The U.S. 10-year Treasury yield was at 4.71% as of August 18, 2026 (−0.38% on the day); the 30-year briefly crossed 5.33% — cited by multiple news sources as a multi-decade milestone — before retreating ahead of FOMC minutes.The combination of a surging long end and a weaker dollar is an unusual mix that raises questions about fiscal credibility rather than simple rate-differential flows; Korean market participants are watching whether FOMC minutes tonight provide guidance that stabilizes the long end.
Reference — brokerages, Wall Street and the windows
A window collecting brokerage research and overseas news
No brokerage reports were retrievable for Wednesday, August 19 (2026); the Naver Research archive does not surface same-day reports after the fact.
No brokerage research reports were retrieved for Wednesday, August 19 (2026) — the Naver Research platform surfaces only currently available reports, and same-day reports are not recoverable retroactively unless collected in real time (which was not done for this session).
15 of 28 calls correct (54%) — measured three trading days after publication.
The Wall Street Scoreboard tracks directional calls from nine named brokerages over a 3-session horizon; as of the current cumulative record, the aggregate hit rate stands at 54% (15 correct out of 28 total calls), with Nomura leading at 4/6 and Goldman Sachs at 3/5; JP Morgan and Barclays are each at 0 correct from their respective call counts.
The day’s wire headlines overlap with several themes already covered in this edition: the 30-year Treasury yield spike, the KOSPI −5.8% close led by semiconductors, SK hynix’s announced ₩40tn share buyback and cancellation program (cited as the largest by a domestic listed company, per Yonhap), and Nvidia chip export controls to China.The Trump-Canada tariff pause (50% tariffs deferred three days, a ‘deal’ announced) was active during the Korean session at 12:18 KST and may have contributed to the intraday bounce seen around 13:00–14:10 KST.
Individual stock detail pages for all names mentioned in today’s edition — including SK hynix, Samsung Electronics, Hanwha Aerospace, Alteogen, and Jusung Engineering — are accessible via the Silmari stock-code links in the Top Ten and Sector blocks above.
Closing today, on to tomorrow
A window that closes today and hands over to tomorrow
Both directional calls (KOSPI −1.5%~−3.0%; KOSDAQ −2.0%~−3.5%) got the direction right but badly underestimated the magnitude — KOSPI fell 5.8% and KOSDAQ fell only 1.17%, suggesting the model captured the semiconductor-led sell-off thesis but did not price in the bond-yield shock amplifier, while simultaneously over-weighting semiconductor drag on KOSDAQ where defensive and bio names cushioned the blow.