Today’s Verdict
KOSPI surges +5.89% to 6,852.58 as semiconductors rebound sharply — morning call missed by a wide margin
The KOSPI closed at 6,852.58 on Thursday, August 20 (2026), +5.89% — a session-wide reversal following Wednesday’s steep decline, driven by double-digit gains in SK hynix and Samsung Electronics.Foreigners were net buyers of ₩1,706.8bn on the KOSPI, reversing two prior days of selling, while retail investors absorbed ₩2,271.2bn on the other side; the KOSDAQ rose a more modest +1.99% to 840.89.
| Index | Close | Today | 1 week ago 08/13 | 1 month ago 07/21 | 1 quarter ago 05/21 | 6 months ago 02/19 | 1 year ago 08/20 |
|---|---|---|---|---|---|---|---|
| KOSPI | 6,852.58 | +5.89% | +0.58% | +1.55% | −12.32% | +20.70% | +118.93% |
| KOSDAQ | 840.89 | +1.99% | −2.38% | +11.62% | −23.97% | −27.55% | +8.14% |
Did our calls hold?
A window grading the morning’s calls against what actually happened
P1 (KOSPI) missed; P2 (KOSDAQ) correct — the morning Philadelphia Semiconductor IndexA US index tracking the performance of 30 semiconductor companies listed on US exchanges, widely used as a global bellwether for chip-sector sentiment.Korea’s top two KOSPI names by turnover are chip makers; overnight SOX moves are a primary input for the morning KOSPI directional model. signal failed to translate into a Korean down day
Of the two morning calls, P1 — KOSPI to fall –0.5% to –2.5% — missed: the index closed +5.89%, an error of roughly eight percentage points at the midpoint.P2 — KOSDAQ to rise +0.5% to +2.0% — was correct; the KOSDAQ closed +1.99%, near the top of the projected band.
No separate sector-level or individual-stock predictions were filed for today’s session.
The day’s path
A window retracing where the index travelled from open to close
KOSPI opened near 6,672, dropped to 6,600.09 at 09:08, then climbed steadily to a high of 6,904.55 at 13:14 before consolidating to close at 6,852.58 — a recovery arc that spanned the full session.
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 net bought ₩1.71tn on KOSPI today, reversing Wednesday’s selling, while retail investors absorbed the other side with ₩2.27tn in Net SellingThe total value of shares sold by an investor category minus the total value bought in the same session — the mirror of net buying.When retail investors net sell into a foreign net-buying day, it often signals a sentiment divergence worth tracking..
| Investor group | Today | 1 week 08.13~08.20 | 1 month 07.21~08.20 | Quarter |
|---|---|---|---|---|
| Foreign investors | +₩1.71tn | +₩3.47tn | +₩691.6bn | −₩68.56tn |
| Retail investors | −₩2.27tn | −₩1.62tn | −₩1.37tn | +₩53.83tn |
| Pension funds | −₩181.6bn | −₩214.1bn | +₩523.4bn | −₩2.65tn |
| Investment firms | −₩317.7bn | −₩2.79tn | −₩1.77tn | +₩14.89tn |
Foreigners net bought ₩1,706.8bn on the KOSPI today — a reversal from the one-week cumulative position, where they remain net buyers of ₩3,474.5bn over the August 13–20 window.In the futures market, foreign accounts were net sellers of 6,978 contracts on August 20, diverging from their cash-market buying — a split that, in the 2026 dataset (153 sessions), has historically attracted closer scrutiny than either signal alone.
Retail investors sold a net ₩2,271.2bn on the KOSPI today, absorbing the foreign buying; over the trailing one month they are net sellers of ₩1,367.5bn.The cross-lag data for the 2026 regime (153 sessions) shows a same-day correlation of –0.85 between foreign Net PurchaseThe total value of shares bought by an investor category minus the total value sold in the same session.Identifies which investor group is the marginal buyer or seller driving price. and retail net buying — today’s pattern fits that relationship closely.
The National Pension Service sold ₩181.6bn on the KOSPI today and is a net seller of ₩214.1bn over the trailing one month; the one-month picture does show a net purchase of ₩523.4bn from the pension fund.Brokerages sold₩317.7bn today and remain the heaviest institutional sellers over the past month at –₩1,774.4bn and over the week at –₩2,794.4bn.
KOSDAQ investor-flow data is not available from today’s collection — the data source supports KOSPI only for the daily and weekly periods.The KOSDAQ’s +1.99% gain against the KOSPI’s +5.89% suggests the semiconductor-driven bounce was a KOSPI-specific event; Alteogen (+11.86%) and Jusung Engineering (+3.32%) were among KOSDAQ advancers.
Over the quarter (May 20 – August 20, 2026), foreigners are net sellers of ₩68,556.3bn on the KOSPI — a structural outflow that makes today’s single-session reversal of ₩1,706.8bn a small offset against the quarterly trend.Retail investors have purchased ₩53,826.3bn net over the same quarter, effectively absorbing the foreign selling; institutional accounts are collectively net buyers of ₩11,874.9bn over the quarter, led by brokerages at +₩14,891.1bn.
Silmari Fear Gauge — past and present
A window measuring market anxiety through volatility, margin lending and short selling
The sentiment gauge held at Neutral (score 0.715) even as the KOSPI surged +5.89% to 6,852.58, with the 20-day volatility reading at the 94th percentile.
The sentiment gauge scored 0.715 today, placing it in the Neutral stage (expanding-window percentile thresholds: 10/35/65/90).The only confirmed today-dated input is vol20 at 6.05%, which sits at the 94th percentile — the single component with the highest weight in the composite (0.225).
The credit-balance five-day change was 4.24% (as of August 19, T+1 release); margin ratio was 0.6 (as of August 19); short-surge ratio was 19.06% (as of August 14, T+2 release) — all inputs reflect prior-period data, not today’s confirmed figures.The panic-buying-on-down-day and no-trigger-streak inputs are marked not applicable because today was an up day (+5.89%).
| Measure | Today’s value | Basis | Where today sits |
|---|---|---|---|
| Retail buying intensity on down days | 0.0 | Current regime (2026) percentile | 69(top 31%) |
| KOSPI 20-day realised volatility | 6.05 | Current regime (2026) percentile | 94(top 6%) |
| Consecutive no-trigger down days | 0.0 | Current regime (2026) percentile | 86(top 14%) |
Today is a trigger day — the KOSPI rose +5.89%, snapping what had been a down sequence; the no-trigger streak resets to zero.The crash-precursor score of 3 (Advance-Decline RatioThe number of advancing stocks divided by the number of declining stocks in a given market on a given day.An extreme ADR reading — very high or very low — is one of the five sub-signals in the crash-precursor score. contributing 2, short-surge 1) reflects lagged data: the ADR reference is the US session of July 28 (2026) at –16.7%; sell-acceleration draws on August 18–19 confirmed flows.
The gauge’s Neutral reading on a +5.89% day illustrates that a sharp rally does not by itself reduce the structural risk flags embedded in the vol20 and short-surge inputs — both reflect conditions that predate today’s session.The judgment is each reader’s own.
The eight inputs to the gauge are: (1) five-day change in credit-balance loans (weight 0.135), (2) margin ratio (0.18), (3) panic-buying on down days (0.09), (4) short-surge ratio (0.18), (5) 20-day realised volatility (0.225), (6) no-trigger-streak count (0.09), and (7) single-stock Single-Stock Leverage ETFAn ETF that delivers a multiple (typically 2×) of the daily return of a single underlying stock, used here to gauge retail speculative activity.The share of leverage ETF turnover in total market turnover is one of the seven inputs to the sentiment gauge. share of turnover (0.10) — scores are combined as a weighted average of expanding-window z-scores to prevent look-ahead bias; a news-fear keyword count is computed as reference only and is not included in the composite.
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
SK hynix’s short-surge signal from August 13–14 sits within a 2026-regime sample where 117 such events averaged –0.22% over the following five days, with a 50% probability of a down move.
The most recent short-surge signals in the data involve SK hynix (surged 4.7× on August 13 and 15.4× on August 14) and Kumho Construction (surged 2.3× and 5.1× on August 12–13).In the current 2026 regime, across 117 short-surge events (defined as short balance doubling in five sessions with a base of at least 50,000 shares), the average five-day return was –0.22% with a 50% probability of a down move; the 2026 baseline for any five-day period is +2.76%, so the excess return from a short-surge event in this regime is –2.98 percentage points — short-surge signals have historically underperformed the regime base rate in 2026.
Where the money moved —12sectors
A window on where money moved from and to, by sector
Semiconductors surged +6.6% as the sector’s dominant names — SK hynix (+12.73%) and Samsung Electronics (+9.49%) — carried the KOSPI to a +5.89% close at 6,852.58, even as financials (−1.69%), construction (−2.00%), and energy/chemicals (−1.51%) declined.
| Sector | Today | Flows | Relative (1w) | Leaders |
|---|---|---|---|---|
| Semiconductors | +6.60% | Buying | — | SK hynix+12.73%· Samsung Electronics+9.49%· Samsung Electro-Mechanics+0.65%· SK Square+11.85%· Jusung Engineering+3.32% |
| AI & Software | +3.80% | Buying | — | NAVER +5.53%· Kakao+3.48%· DearU+2.39% |
| Power & Electrical | +0.03% | Selling | — | LS ELECTRIC −1.39%· Doosan Enerbility−0.39%· HYOSUNG Heavy Industries−1.75%· HD Hyundai Electric−0.80%· Gaon Cable+4.50% |
| Electronics & Components | +3.32% | Buying | — | Samsung Electronics (Pref.)+10.07%· Samsung SDI+2.57%· LG Electronics+0.50%· LG Energy Solution+0.14% |
| Autos | −0.32% | Buying | — | Hyundai Motor+0.85%· Kia−1.43%· Hyundai Mobis−0.39% |
| Defense & Aerospace | −0.91% | Buying | — | Hanwha Aerospace−0.85%· LIG Defense & Aerospace−1.13%· Korea Aerospace Industries (KAI)−0.74% |
| Shipbuilding & Shipping | −1.21% | Buying | — | Hanwha Ocean+0.45%· HD KSOE (Korea Shipbuilding & Offshore Engineering)−1.77% · HMM −2.30% |
| Financials | −1.69% | Selling | — | KB Financial Group−3.85%· Hana Financial Group−3.22%· Shinhan Financial Group−3.71%· Mirae Asset Securities+4.03% |
| Bio & Healthcare | −0.65% | Buying | — | Alteogen+11.86%· Kolon TissueGene−16.41%· Samsung Biologics+1.94%· Celltrion+0.00% |
| Construction & Infrastructure | −2.00% | Selling | — | Hyundai E&C−2.32%· Daewoo E&C−2.85%· DL E&C−0.84% |
| Energy & Chemicals | −1.51% | — | — | SK Innovation−2.33%· LG Chem−0.75% · S-Oil −5.94%· Lotte Chemical+2.98% |
| Consumer & Entertainment | +0.56% | Selling | — | SK Telecom−1.43%· HYBE+0.70%· CJ CheilJedang+2.61% · JYP Ent. +0.38% |
The stocks that moved the market — top by turnover10
A window on which investor groups backed the most heavily traded stocks
SK hynix (₩910.96bn turnover, +12.73%) and Samsung Electronics (₩696.07bn, +9.49%) together accounted for the top two KOSPI turnover slots by a wide margin.
SK hynix (₩910.96bn) and Samsung Electronics (₩696.07bn) together accounted for approximately half the total KOSPI turnover implied by the top-ten list, with Samsung Electro-Mechanics a distant third at ₩106.28bn.On the KOSDAQ, Alteogen led at ₩336.7bn, followed by Ingenium Therapeutics (Reg.S) at ₩297.0bn and HPSP at ₩251.5bn — the KOSDAQ list shows more dispersion than the KOSPI, which was heavily concentrated in two names.
| Stock | Close | Change | Turnover | Foreign investors | Institutions | Investment firms | Pension funds | Retail investors |
|---|---|---|---|---|---|---|---|---|
| SK hynix | ₩1,691,000 | +12.73% | ₩9.11tn | +₩539.3bn | −₩24.1bn | −₩211.8bn | +₩20.1bn | −₩1.55tn |
| Samsung Electronics | ₩271,000 | +9.49% | ₩6.96tn | +₩1.14tn | +₩159.3bn | −₩86.3bn | −₩23.5bn | −₩1.27tn |
| Samsung Electro-Mechanics | ₩1,396,000 | +0.65% | ₩1.06tn | −₩230.9bn | −₩104.0bn | −₩53.5bn | −₩49.8bn | +₩327.8bn |
| SK Square | ₩1,123,000 | +11.85% | ₩927.6bn | +₩77.1bn | −₩18.7bn | −₩8.5bn | +₩3.6bn | −₩56.5bn |
| Samsung Electronics (Pref.) | ₩191,200 | +10.07% | ₩674.5bn | +₩49.3bn | +₩71.3bn | +₩16.1bn | +₩11.5bn | −₩121.7bn |
| SK eternix | ₩56,000 | −3.11% | ₩394.2bn | −₩13.8bn | −₩16.9bn | −₩7.0bn | +₩2.5bn | +₩32.1bn |
| Kumho E&C | ₩15,650 | +24.21% | ₩390.6bn | +₩6.5bn | +₩0.9bn | +₩0.3bn | +₩0.1bn | −₩6.2bn |
| Hanwha Aerospace | ₩1,167,000 | −0.85% | ₩295.9bn | +₩16.4bn | +₩7.1bn | +₩13.0bn | −₩4.3bn | −₩22.4bn |
| NAVER | ₩219,500 | +5.53% | ₩210.5bn | +₩41.7bn | +₩16.3bn | −₩0.1bn | +₩14.6bn | −₩57.4bn |
| KB Financial Group | ₩160,000 | −3.85% | ₩206.9bn | −₩13.8bn | −₩43.0bn | −₩23.9bn | −₩11.7bn | +₩56.3bn |
Gainers5· Decliners5 — KOSPI & KOSDAQ
A window on the biggest gainers and decliners, and the reasons behind them
KOSPI breadth data was not collected for August 20; the prior session (August 19) showed 171 advancers against 703 decliners, making today’s broad-based advance a sharp reversal in character.
KOSPI breadth data for August 20 was not collected due to a data-availability issue; the prior session (August 19) showed only 171 advancers against 703 decliners (ADR 0.24), with a top-10 concentration ratio of 67.5%.On the KOSPI leaderboard today, the up-move list is dominated by semiconductor and broker names (SK hynix +12.73%, SK Square +11.85%, Samsung Electronics +9.49%), while the decliners list is led by DN Automotive (–13.77%) and financials/energy stocks — suggesting the rally was not uniformly broad.
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
The KOSDAQ rose +1.99% to 840.89, gaining ground but lagging the KOSPI’s +5.89% by 3.90 percentage points — a significant divergence on a strong up day.
The KOSDAQ closed at 840.89 (+1.99%), lagging the KOSPI’s +5.89% by 3.90 percentage points — the gap reflects the KOSPI’s heavy concentration in large-cap semiconductor names that drove most of the index gain.KOSDAQ investor-flow data was not collected for today; on a stock-by-stock basis, Alteogen (+11.86%) and Ingenium Therapeutics (+30.00%) were notable advancers, while Kolon TissueGene (–16.41%) was the session’s most active decliner.
Semiconductors → defensives, and back — by regime
A window on the pattern in sector rotation — money circulating from one sector to another
Today does not qualify as a defensive rotation day: semiconductors surged (+12.73% SK hynix, +9.49% Samsung Electronics) rather than declining the required 2.0%+.
| 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 does not qualify as a defensive rotation event under the data definition (semiconductor average down ≥2.0% plus defensives outperforming by ≥2.0pp): SK hynix rose +12.73% and Samsung Electronics +9.49%.For reference, in the 2026 regime, the 32 past rotation events were followed three days later by an average return of +2.05% with a 69% up-probability — but that base rate does not apply today as the trigger condition was not met.
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 crash-precursor score stood at 3 out of a possible maximum, driven by two ADR sub-signals and one short-surge sub-signal, with sell-acceleration and sentiment sub-signals at zero.
The crash-precursor score of 3 reflects two ADR sub-signals (referenced from the US session of July 28, 2026, at –16.7%) and one short-surge sub-signal (short-balance data as of August 14, T+2 publication); the sell-acceleration and extreme-sentiment sub-signals are both zero.A score of 3 is a partial reading — two of the five signal categories are active — and should be interpreted alongside the lagged data dates: the ADR input is now more than three weeks old, and the short-surge input is six sessions old; neither is a fresh confirmation.
Tonight — the U.S. session about to open
S&P 500 futures +0.21% and Nikkei futures +0.58% point to a steady open, but the SOX’s prior –2.12% and hawkish FOMC minutes leave the direction of US semiconductor stocks as tonight’s primary watch.
Korea–U.S. mutual following — overnight grading
A window on which market followed which
The prior night’s SOX fell –2.12% yet the KOSPI closed +5.89%, making today a clear divergence from the prevailing US-leads-Korea pattern seen in 39 of 139 sessions year-to-date in 2026.
The SOX fell –2.12% on August 19, which our morning model read as a bearish signal for Korea; the KOSPI instead gained +5.89%, making today a case where Korea diverged from, rather than followed, the prior night’s US semiconductor signal.The Nikkei 225 closed at 66,216.79 (+1.36% as of August 20), providing a partial regional tailwind; the iShares MSCI South Korea ETFA US-listed exchange-traded fund tracking MSCI’s South Korea index, used as a proxy for how foreign investors price Korean equity risk in real time.EWY’s prior-day move often anticipates or confirms the direction of foreign net buying in the KOSPI the following session. (Korea ETF) closed at 174.43 (+2.58%) as of August 19, suggesting foreign positioning had already begun to shift before today’s session.
In 2026 year-to-date (139 sessions), Korea has followed the US 39 times, the US has followed Korea 30 times, bidirectional follow-through occurred 46 times, and 24 sessions showed no clear follow-through in either direction.Today falls into the no-follow or Korea-leads category — the prior SOX signal did not translate into the expected KOSPI direction, which has now happened in at least 24 sessions this year where neither market led the other cleanly.
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-dollar rate stood at ₩1,394.3 and the dollar index at 98.58, while the yen-won cross was 880.57 per 100 yen, as of the latest accumulated reading.
The won-dollar rate stood at ₩1,394.3 and the dollar index (DXY) at 98.58, with the yen at 880.57 won per 100 yen, according to the accumulated strip data; a separate intraday won-dollar reading for today was not collected.The dollar index (spot) was 98.64 as of August 20, down 0.19% on the day — a mild dollar softening that is consistent with a risk-on environment, though the data does not establish a causal link to today’s equity move.
Rates — a weaker link than commonly assumed
A window on the burden rates and bonds place on equities
The US 10-year Treasury yield was 4.65% as of August 19, down 1.13% on the day, after the July FOMC minutes flagged that a majority of officials discussed the possibility of further rate hikes if inflation does not cool.
The US 10-year Treasury yield was 4.65% as of August 19, down 1.13% on the day after the Treasury announced a debt-buyback programme that provided some relief to the long end.The July FOMC minutes, released Wednesday night KST, showed a majority of officials discussed the possibility of rate hikes if inflation does not cool — a hawkish nuance that limited the yield rally; after-hours reporting noted yields edged higher as traders continued to digest the buyback plan.
Reference — brokerages, Wall Street and the windows
A window collecting brokerage research and overseas news
No brokerage reports were retrievable for today; the Wall Street scoreboard stands at 15 hits in 28 tracked calls (54%) across nine banks over a 3-session horizon.
No brokerage research reports were retrievable for today’s session — the data source (Naver Research) provides only current-window reports, and no same-day reports were captured during the collection run.
15 of 28 calls correct (54%) — measured three trading days after publication.
The Wall Street scoreboard tracks directional calls published by nine banks over a rolling three-session horizon; a call is scored as a hit if the market moved in the predicted direction within three sessions of the publication date. The current tally stands at 15 hits out of 28 tracked calls (54% overall), with Nomura leading at 4/6 and Goldman Sachs at 3/5; JP Morgan and Barclays have each recorded zero hits in their tracked calls.
Today’s event calendar items overlap with the macro and rates blocks above — the July FOMC minutes (majority discussed rate hikes), the Treasury debt-buyback plan (yields lower initially, then edging higher after hours), and Google’s AI-chip alliance with Marvell (up to ₩17tn in share warrants) were the pre-market headlines most relevant to today’s session.
For individual company details — SK hynix, Samsung Electronics, Samsung Electro-Mechanics, NAVER, Alteogen, Jusung Engineering — see the Top Ten and Up-Down blocks; no analyst report data is available for today.
Closing today, on to tomorrow
A window that closes today and hands over to tomorrow
The morning call on the KOSPI (P1: –0.5% to –2.5%) missed decisively — the index closed +5.89% — a reminder that a prior-night SOX decline does not override short-covering momentum after an extreme drawdown day; the KOSDAQ call (P2: +0.5% to +2.0%) was correct at +1.99%.