Today’s Calls
Bond shock + Philadelphia Semiconductor IndexA U.S. index tracking the share prices of major semiconductor design and manufacturing companies.Moves in the SOX have historically preceded same-direction moves in the KOSPI the following session, given Korea’s heavy semiconductor export exposure. rout arrive together — Wednesday open watches whether foreign buyers return or the August 18 pattern repeats
Wednesday, August 19 (2026) opens under a simultaneous rate and semiconductor shock: the 30-year Treasury yield crossed 5.33% overnight, the SOX fell −4.98% on Tuesday, and the Nikkei 225 CME futures are indicated −2.37% as of 05:00 KST.The prior session (Tuesday, August 18 (2026)) saw KOSPI program non-arbitrage net selling of −₩10,885bn, Samsung Electro-Mechanics close −7.57%, and Samsung SDI −5.43%; the one-week foreign net buying position on KOSPI remains +₩8,129.2bn, but whether that cushion holds today is the session’s central question.
Today’s Calls
Where the day’s calls are placed by number — grading starts with the Early Session edition
Today’s call: KOSPI −1.5% to −3.0%, KOSDAQ −2.0% to −3.5% — SOX, Advance-Decline RatioThe number of rising stocks divided by the number of falling stocks over a given session.A sharp ADR decline signals broad-based selling rather than rotation, and is one of the six inputs in The Silmari’s crash-precursor score., and rate-shock signals all point lower
Two predictions are on record for today (Wednesday, August 19 (2026)), published at 07:30: KOSPI direction down, magnitude −1.5% to −3.0% (P1), and KOSDAQ direction down, magnitude −2.0% to −3.5% (P2).These are pre-open forecasts and carry no score today — scoring will appear in the evening edition once closing data are confirmed.
No sector-level predictions are filed for today; sector-flow data are not collected in real time, and the August 18 (2026) lesson — that directional calls on individual sectors have been among the least reliable outputs in recent sessions — counsels restraint.
The world overnight — how the US session ended
A window on what happened in the US market overnight
S&P 500 −0.69%, Nasdaq −1.33%, SOX −4.98% — 30-year Treasury yield breaches 5.33%, a 19-year high per event data
Wall Street closed lower Tuesday, August 18 (2026): the S&P 500 at 7,691.76 (−0.69%), the Nasdaq at 26,289.71 (−1.33%), and the SOX at 11,992.46 (−4.98%); the event calendar records the 30-year Treasury yield crossing 5.33%, described as a 19-year high, driven by inflation and fiscal spending concerns.The Wall Street scorecard covering the three-day horizon shows a cumulative hit rate of 54% (15/28) across nine brokerages — a reminder that even with a directionally clean overnight signal, forecast reliability in this regime is modest.In 2026 YTD, the KOSPI followed a SOX move of this magnitude (≥ 0.5% in absolute terms, same direction next day) in 39 of 139 sessions — the base rate alone does not make a directional call, but the coincidence of a rate shock, geopolitical noise (Trump-Hormuz comments per the event calendar), and pre-existing battery-sector weakness adds weight to the downside scenario for today.
Korea–U.S. mutual following — overnight grading
A window on which market followed which
SOX −4.98% overnight — in 2026 YTD, Korea has followed U.S. semiconductor moves in 39 of 139 sessions
The Philadelphia Semiconductor Index closed −4.98% on Tuesday, August 18 (2026), while the S&P 500 fell −0.69% and the Nasdaq dropped −1.33%.In the 2026 YTD sample of 139 sessions, Korea followed U.S. direction (SOX ≥ 0.5% move, same-direction KOSPI next day) in 39 cases, while bidirectional co-movement appeared in 46 cases and no follow-through in 24 — making mechanical inference from a single overnight SOX print unreliable on its own.
The 2026 YTD cross-follow tally shows Korea tracking the U.S. in 39 sessions versus the U.S. tracking Korea in 30, with bidirectional alignment the most common outcome at 46 sessions.The structural takeaway is that the relationship is asymmetric but not deterministic: a SOX decline of the magnitude seen Tuesday raises the probability of a negative open, but past samples show non-trivial exceptions — particularly when foreign futures positioning diverges from cash, as occurred on August 18 (2026) when foreign investors were net buyers of 808 contracts in futures even as institutional investors net sold 2,252 contracts.
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
Night window —EWYofficial indicator
A window on what overnight futures foreshadow for the next day’s open
Overnight futures: S&P 500 −0.37%, Nasdaq 100 −1.12%, Nikkei CME −2.37% as of 05:00 KST
As of 05:00 KST, the overnight U.S. and Nikkei futures read: S&P 500 futures at 7,713.25 (−0.37% from the August 18 15:00 KST reference), Nasdaq 100 futures at 29,559.5 (−1.12%), and Nikkei 225 CME futures (yen-denominated) at 66,070 (−2.37%).These are CME-linked proxies for global risk sentiment, not the Korean KOSPI 200 night session; the figures carry an estimated ±1-hour timing error given the hourly-bar approximation, and their translation into a KOSPI open gap is subject to the 39-of-139 follow-through rate described above.
Pre-open08:00~09:00 — single-price auction (open/close)The single-price auction window (before the open and just before the close), where orders are pooled and matched at once.When large volume crowds into this window, a gap is created.forecast
A window on where the pre-open auction is pulling the opening price
Pre-open watch: gap direction on Samsung Electronics and SK hynix the key tell at 08:30
At 07:30, the simultaneous-bid auction (08:30–09:00) has not yet begun — gap direction should be read from how Samsung Electronics and SK hynix open, given that those two names accounted for ₩87,733bn and ₩66,169bn of KOSPI turnover on Tuesday respectively and the NXT after-market snapshot showed both indicated lower.A secondary watch is whether the battery-sector selling that hit Samsung SDI (−5.43% in regular trade Tuesday) and Samsung Electro-Mechanics (−7.57%) extends or stabilises at the open — in past sessions where multiple large-cap names gapped sharply on an SOX decline, program selling in the non-arbitrage book has amplified the move, as seen on August 18 (2026) when KOSPI non-arbitrage program net selling reached −₩10,885bn.
Previous-Day Review
A window that retraces what happened in the previous session
Tuesday’s lesson: program non-arbitrage selling of −₩10,885bn dominated while foreign futures buyers held 808 contracts — cash and derivatives diverged
The Silmari Fear Gauge
A window measuring market anxiety through volatility, margin lending and short selling
Crash-precursor score at 3 — ADR and short-surge signals both active ahead of Wednesday’s open
The composite crash-precursor score stands at 3 this morning, with two sub-signals lit: the ADR component (based on the U.S. session reading of −16.7% dated July 28 (2026)) and the short-surge component (based on short-interest data as of August 12 (2026), the most recent T+2 publication reflected in the system).The sentiment composite for today (Wednesday, August 19 (2026)) has not yet been computed — the gauge’s inputs require the day’s closing data, so the live reading will appear in the evening edition.
In the current regime (2026), when a short-surge event has been recorded, the KOSPI’s five-day-forward average return has been −0.50% with a 51% probability of a down move — essentially coin-flip odds, but with a negative skew against the regime baseline of +2.87% (excess: −3.37%p), based on 111 events since 2026.The most recent surge events on record involve SK hynix (August 10–11 (2026), surge multiples of 7.8× and 12.1×), where the five-day return after the August 10 event was +17.04% — a reminder that surge events in this name have resolved to the upside recently, complicating any mechanical bearish read.
Today carries multiple concurrent inputs: the SOX fell −4.98% on Tuesday, August 18 (2026); the 30-year U.S. Treasury yield crossed 5.33% overnight, per event-calendar data; and the Nikkei 225 CME futures are indicated down −2.37% as of 05:00 KST.Per the letter’s standing rule, no single cause is assigned when several events overlap — all three pressures are live simultaneously and their combined weight on today’s open cannot be disentangled from the data available at 07:30.The judgment is each reader’s own.
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
Won at ₩1,413/$ with the dollar index at 99.65 — yen cross at ¥885.09 per ₩100
The won stood at ₩1,413 per dollar as of the data snapshot, with the DXY dollar index at 99.65.The yen-won cross is quoted at 885.09 yen per ₩100, a level that bears watching given the Nikkei 225 CME futures are indicated −2.37% overnight — yen strength accompanying a Nikkei decline historically compresses the yen-funded carry trades that have supported Korean equity inflows in 2026.
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 closing data not yet confirmed — prior session saw battery and electronics names lead declines
Warning
A window flagging in advance where today’s session calls for caution
Crash-precursor score 3, SOX −4.98%, 30yr Treasury at 5.33% — three concurrent pressure signals at the open
The crash-precursor score entering today’s session is 3 out of a possible 6 scored signals, with ADR and short-surge both active; the sell-acceleration and sentiment sub-signals are either at zero or not yet updated.In the current regime (2026), short-surge events have preceded a five-day KOSPI average of −0.50% with a 51% down probability across 111 events — statistically near-neutral but with a negative skew vs. the regime baseline.The lesson from August 18 (2026) is also live: the prior session saw Samsung Electro-Mechanics fall −7.57% and Samsung SDI fall −5.43% in regular trading, while the NXT after-market snapshot showed Samsung Electronics indicated at −4.37% and SK hynix at −1.82% — concentrated selling in large-cap tech that, in past sessions with multiple overlapping signals, has carried over to the next open more often than not in 2026.