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SOX +2.56% Lands on Monday — Does Seoul Follow? — Korea Market Pre-Open, Aug 10, 2026

The Philadelphia Semiconductor Index closed up 2.56% on Friday, August 7 (2026), while the S&P 500 added 0.62% and the Nasdaq rose 1.30% — giving Korean equities a constructive overnight backdrop as Monday’s session, August 10 (2026), approaches.At the same time, the 2026-regime day-of-week record f

The Silmari
A daily data newsletter on the Korean stock market — silmari, ‘a clue: the loose end that unravels the knot’
① Pre-Open 07:302026.08.10 Mon · No. 8Crash-precursor score 2/active signals 1 (ADR only) — sentiment gauge reading not yet confirmed for August 10 (2026)
① Pre-Open · published 07:30 KST · before the open
01 · VerdictRegular session confirmed 15:30 KST

Today’s Calls

Philadelphia Semiconductor IndexA U.S. index tracking roughly 30 companies involved in semiconductor design, distribution, and manufacturing.Its overnight move is the single most-cited external input for Korean chip-stock direction at the morning open. +2.56% Lands on Monday — Does Seoul Follow?

The Philadelphia Semiconductor Index closed up 2.56% on Friday, August 7 (2026), while the S&P 500 added 0.62% and the Nasdaq rose 1.30% — giving Korean equities a constructive overnight backdrop as Monday’s session, August 10 (2026), approaches.At the same time, the 2026-regime day-of-week record for Mondays shows an average KOSPI move of –0.5% with a 57% up-rate across 28 sessions, and foreign net selling on 75% of those days — a structural headwind that tempers the positive U.S. close.

Key points
01SOX rose +2.56% on August 7 (2026); in the current 2026 regime, the KOSPI has risen the following session in 77% of cases after SOX gains of that magnitude (n=52 per P1 basis).
02Monday seasonality in 2026 works against the bulls: average KOSPI return of –0.5%, foreigners net-selling on 75% of Mondays (n=28), with an average foreign net outflow of ₩1,241.4bn per Monday session.
03The crash-precursor score stands at 2 out of a possible higher reading, with only the Advance-Decline RatioThe ratio of rising stocks to falling stocks on a given exchange over a session.An extreme negative ADR reading is one of four sub-signals feeding the crash-precursor composite score used in this letter. signal active at –16.7% (U.S. session, July 28 (2026)); short-surge, forced-selling, and sentiment signals are all at zero.
04The won strengthened to ₩1,407.33 per dollar (–1.05% as of August 9 (2026)), and iShares MSCI South Korea ETFA U.S.-listed exchange-traded fund that tracks large- and mid-cap Korean equities.EWY’s after-hours move provides a real-time proxy for foreign sentiment toward Korean equities before the Seoul open. closed up +1.2% on August 7 (2026) — two external signals broadly consistent with a firmer open, though Monday-regime flows and multi-cause overlap warrant caution.
02 · Prediction2 calls · posted 07:30 KST

Today’s Calls

Where the day’s calls are placed by number — grading starts with the Early Session edition

Two calls on the board: KOSPI +1.0~+2.0%, KOSDAQ –0.3~+0.5% — scoring pending close

Two predictions were logged for today, Monday, August 10 (2026): P1 calls for KOSPI +1.0% to +2.0%, and P2 calls for KOSDAQ flat to slightly positive (–0.3% to +0.5%).These are pre-open calls made at 07:30; scoring will be applied after the close once confirmed data are available.

calls placed today
posted 07:30 KST
Direction grading
from the 10:00 Early Session edition
Magnitude grading
settled in the 20:00 Final Edition
Call ① KOSPIThe KOSPI is more likely to rise
Band +1.0~+2.0% · full day
Morning rationaleSOX +2.56% Next-day avg +2.15%·Upside probability 77% (n=52) + Morgan Stanley positive pivot report fuels foreign investor inflow shift expectations
Call ② KOSDAQKOSDAQ is more likely to finish flat
Band -0.3~+0.5% · full day
Morning rationaleLeverage product regulation impact reduces trading volume·weakens short-term flows + Semiconductor mega-caps capital reinflow risks sidelining KOSDAQ vs biotech defense

No prediction was entered for individual sectors or foreign net-flow direction, as the Monday-regime structural headwind and multi-signal overlap made directional conviction on sub-indices insufficient to warrant a call.

03 · OvernightOvernight, confirmed abroad

The world overnight — how the US session ended

A window on what happened in the US market overnight

SOX +2.56% leads Wall Street higher on August 7 (2026); sell-side scorecard at 54% over 28 calls

EWY (Korea ETF)166.09 (+1.20%· as of 2026-08-07)
Nikkei 22565606.71 (−0.12%· as of 2026-08-07)
Dollar index99.62 (+0.02%· as of 2026-08-09)
U.S. 10-year Treasury4.66 (−0.21%· as of 2026-08-07)
KRW/USD1407.33 (−1.05%· as of 2026-08-09)
Nasdaq26690.62 (+1.30%· as of 2026-08-07)
SOX semiconductors12356.79 (+2.56%· as of 2026-08-07)
S&P5007757.64 (+0.62%· as of 2026-08-07)

Wall Street’s sell-side scorecard stands at 54% directional accuracy over 28 calls (horizon: 3 days); individual desk records range from 0-for-3 (JP Morgan, Barclays) to 4-for-6 (Nomura), cautioning against treating any single house view as authoritative.Friday’s SOX gain of +2.56% is the primary overnight input; in the 2026 regime, the KOSPI has posted a positive follow-through session after SOX moves of that magnitude in 77% of cases (n=52, per the P1 basis recorded in the prediction log), though Monday-regime seasonality and multi-signal overlap mean several forces are pulling simultaneously.

04 · Cross-followingMeasured in 2026

Korea–U.S. mutual following — overnight grading

A window on which market followed which

Korea followed the U.S. in 39 of 139 sessions year-to-date (2026); both directions active in 46

On Friday, August 7 (2026), the SOX rose +2.56%, the Nasdaq +1.30%, and the S&P 500 +0.62%, providing a positive overnight read-across into Monday’s KOSPI open.EWY, the U.S.-listed Korea ETF, closed up +1.2% on the same day, broadly corroborating the directional signal.

In 2026 year-to-date across 139 sessions, Korea followed the U.S. (prior-night SOX ≥ 0.5% move, same-direction KOSPI) on 39 occasions; the U.S. followed Korea on 30; both moved in the same direction on 46 days; and neither followed on 24 days.The data do not establish a mechanical lock-step — on 54 of those 139 sessions, at least one market did not mirror the other.

Days Korea followed the U.S.39 days
Days the U.S. followed Korea30 days
Both ways46 days
Sample139 days

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

05 · Night windowOvernight indicators

Night window —EWYofficial indicator

A window on what overnight futures foreshadow for the next day’s open

S&P 500 +0.62%, Nasdaq +1.30%, SOX +2.56% — Nikkei 225 edges down 0.12% (all August 7, 2026)

EWY (Korea ETF)166.09 (+1.20%· as of 2026-08-07)
Nikkei 22565606.71 (−0.12%· as of 2026-08-07)
Dollar index99.62 (+0.02%· as of 2026-08-09)

U.S. and Nikkei futures advanced overnight — as of 5 a.m. (Korea time) following the close of Korea markets, S&P 500 futures were +0.54%, Nasdaq 100 futures were +0.95%, and Nikkei 225 CME futures (yen-based) were +0.91%.No separate sample data is publicly available on the frequency of Kospi moving in the same direction on days following overnight closes when both U.S. and Nikkei futures ended in positive territory on a 2026 current basis, and the judgment of how Korean markets will open today is each investor’s responsibility.

06 · Pre-openPre-open check

Pre-open08:00~09:00single-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

Opening GapThe difference between today’s opening price and the prior session’s closing price, expressed in points or percentage.Gap direction and magnitude at the 09:00 open are the immediate test of whether the overnight SOX rally has been priced into Korean equities. direction hinges on SOX +2.56% vs. Monday’s 75% foreign net-selling rate (n=28, 2026)

With the simultaneous-bid session (08:30–09:00) not yet open at publication time (07:30), the key question for the gap direction is whether the SOX +2.56% tailwind outweighs Monday’s structural foreign net-selling tendency — the data assign a 75% probability to foreign outflow on Mondays in 2026 (n=28).Sector leadership to watch: power/electric infrastructure outperformed KOSPI by +13.9%p over the past week and defense/aerospace by +24.7%p; whether semiconductor names reclaim leadership after the SOX move is a secondary read-across to monitor at the open.

KOSPIClose6,258.77· same-day−0.60%
KOSDAQClose798.81· same-day−0.36%
Historical contextIn 2026, Mondays have averaged a KOSPI swing range of ±3.46%p intraday — wider than Tuesday through Thursday averages — across 28 sessions.
07 · ReviewConfirmed, previous session

Previous-Day Review

A window that retraces what happened in the previous session

Monday, August 10 (2026): SOX tailwind meets Monday-regime foreign selling headwind

KOSPIClose6,258.77· same-day−0.60%
KOSDAQClose798.81· same-day−0.36%
08 · Fear gaugeStanding gaugeSilmari Fear Gauge reference time — not yet set

The Silmari Fear Gauge

A window measuring market anxiety through volatility, margin lending and short selling

Crash-precursor score holds at 2 — ADR the sole active signal

Volatility percentile
To be compiled
Silmari Fear Gauge percentile basis — to be stated

The sentiment gauge reading for today is not yet available (the dashboard value reflects August 7 (2026) as the latest confirmed input).The crash-precursor composite scores 2: the ADR sub-signal is active at –16.7% (U.S. session, July 28 (2026)), while the short-surge, forced-selling-acceleration, and sentiment-above-90 sub-signals each read 0.

Historical base rates for the current regime (2026–): after a short-surge event, the KOSPI averages –1.89% over five sessions, with a 54% down-probability (n=96); in the 2025 transition regime the equivalent average was +1.35% (n=111), illustrating how regime context materially shifts the distribution.

No fresh crash-precursor trigger is active today beyond the pre-existing ADR signal; the short-surge and forced-selling signals remain at zero as of the most recent confirmed data (short-position disclosure current through August 6 (2026), flow data through August 7 (2026)). The judgment is each reader’s own.

09 · FX windowFX window · reference time to be set

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 firms to ₩1,407.33 per dollar, a –1.05% move as of August 9 (2026)

USD/KRW (Aug 9, 2026)₩1,407.33 (–1.05%)
Dollar Index (Aug 9, 2026)99.62 (+0.02%)
U.S. 10-yr yield (Aug 7, 2026)4.66% (–0.21%)

The won traded at ₩1,407.33 per dollar as of August 9 (2026), a move of –1.05% (won strengthening).The dollar index stood at 99.62 as of the same date, up 0.02%, while the U.S. 10-year Treasury yield was 4.66% as of August 7 (2026), down 0.21% on the day — a backdrop that has historically been associated with emerging-market currency firming, though the causal path runs through multiple channels.

10 · KOSDAQ windowKOSDAQ flow and price data for August 10 (2026) are not yet available pre-open; figures below reflect the trailing week (August 3–10, 2026) and longer windows.

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 net-flow data unavailable pre-open; sector relative strength the only guide

KOSPI · KOSDAQ close6,258.77 · 798.81
Today’s change−0.60% · −0.36%
Today’s gap (KOSPI − KOSDAQ)−0.24%p— below the 2pp promotion threshold
Year to date+45.23% · −15.52%
Silmari Decoupling Gauge — year-to-date gap+60.75%p
Foreign net buying — KOSPI · KOSDAQ+₩0.0bn · +₩0.0bn
Retail net buying — KOSPI · KOSDAQ+₩0.0bn · +₩0.0bn
Investment firms’ net buying — KOSPI · KOSDAQ+₩0.0bn · +₩0.0bn
Pension funds’ net buying — KOSPI · KOSDAQ+₩0.0bn · +₩0.0bn
11 · WarningToday omen score 2 pts = CAUTION — Criteria: 3+ pts crash alert·2 pts caution (small sample)

Warning

A window flagging in advance where today’s session calls for caution

Crash-precursor score 2; short-surge window for Samsung Electronics and SK hynix not yet elapsed

The crash-precursor score is 2, with only the ADR sub-signal active; in past sessions where this score was in the low single digits, the market did not systematically sell off, but the data do not establish immunity either.Samsung Electronics and SK hynix both registered short-surge events between July 23–28 (2026); in the current 2026 regime, five sessions after a short-surge event the KOSPI averaged –1.89% with a 54% down-probability (n=96) — that window is not yet fully elapsed.Monday foreign net-selling probability in 2026 stands at 75% (n=28); on days with concurrent negative foreign flow and a high-volatility backdrop, forced-selling pressure can concentrate in the 14:00–15:00 window — a pattern visible in the 2026 sample but not guaranteed to repeat.

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.