The Silmari

A daily data newsletter on the Korean stock market — silmari, ‘a clue: the loose end that unravels the knot’

⑤ After-Hours 18:002026.08.28 Fri · No. 25Caution — KOSPI closed at -1.79% with foreign investors selling a net -KRW 1,756.4bn. KOSDAQ held at +0.09%, so the two indices parted ways, and after hours more names are higher than lower. The flow figures are provisional and are settled this evening.

⑤ After-Hours · published 18:00 KST · after the regular session · Note: flow figures are preliminary as published just after the close; the exchange’s confirmed figures appear in that day’s Final Edition (20:00 KST).

① Pre-Open07:30 ② Early Session10:00 ③ Midday12:00 ④ Closing16:00 ⑤ After-Hours18:00 ⑥ Final20:00

01 · VerdictRegular session confirmed (2-source reconciliation)

verdict at evening

A day staked to the upside closed at -1.79% — the two indices parted ways

KOSPI closed at 6,788.88, down -1.79% on the day, while KOSDAQ closed at 838.41, up +0.09%. Both closing levels are exchange-confirmed, with the two sources in agreement.This morning both indices were staked to the upside. KOSPI went the other way; KOSDAQ held on to a narrow gain.Production constraints meant the 12:00 midday edition and the 16:00 closing edition could not be published today. What those two would have carried — the closing path and the end-of-day scoring — is set down in this edition instead.

Key points

01The close is settled — KOSPI 6,788.88 (-1.79%) and KOSDAQ 838.41 (+0.09%), confirmed against both sources. Yesterday the figure would not narrow to one by evening; today it has closed.

02All five calls landed inside their bands; two had the direction right — KOSDAQ at +0.09% and Samsung Electro-Mechanics at +2.6% were staked to the upside and rose, while KOSPI -1.79%, SK hynix -4.45% and Samsung Electronics -3.38% went the other way. Inside the band and right on direction are different things.

03The most heavily staked call was wrong — KOSPI was placed at an advance probability of 77% (based on 207 similar cases) and closed at -1.79%. This morning’s pages stated that 77% means the outcome went the other way two or three times in ten; today fell among those.

04Foreign investors sold heavily — on KOSPI they sold a net -KRW 1,756.4bn, with institutions at -KRW 284.2bn and investment firms at -KRW 306.5bn, while retail investors absorbed it with +KRW 424.3bn of net buying. These figures were collected before 19:00 and are settled in the evening.

02 · NXTNextrade (NXT)An alternative trading system opened in 2025 alongside the Korea Exchange, running pre-market and after-market sessions around regular hours.It shows the temperature of flow after the main session closes, but it is not a main session figure, so values from the two venues must not be mixed for the same name.NXT intraday — 20-minute delay · as of 17:25 KST

Evening disclosures —Short sellingShort sellingSelling borrowed shares first, betting the price will fall.A rising balance means more money is betting on a decline.balance

A window on whether the regular session’s move carried into the evening alternative venue

More names are higher after hours — yet the two carrying the turnover are lower

The Nextrade snapshot is a 20-minute delayed reading as of 2026-08-28 17:25. It is not a settled figure for the day, and it is not a Korea Exchange main-session number.Of the 606 names covered, 347 rose, 237 fell and 22 were unchanged, with total turnover of KRW 10,748.0 bn. By count, the advancing side is larger.The turnover leaders run the other way — SK hynix at -4.28% (KRW 2,564.4 bn) and Samsung Electronics at -3.38% (KRW 2,031.2 bn) remain lower as they were in the main session, while Samsung Electro-Mechanics +1.73% (KRW 806.4 bn), Doosan Enerbility +2.1% and NAVER +1.15% are higher.No settled tally exists for today yet — the most recent settled day is 27 August, when Nextrade turnover totalled KRW 16,530.9 bn for a market share of 12.39%.

03 · Gap risksRisk → same condition in the past → outcome distribution

Tomorrow morninggap risks 4names

A window naming in advance what could shake tomorrow’s opening price

The two names that weighed on the main session are still lower after hours

ADRAdvance Decline Ratio (ADR)The number of advancing issues divided by the number of declining issues over a period, measuring how the whole list of stocks moved rather than the index. Above 1 means more names rose than fell.When the index rises while this ratio sits below 1, as it did yesterday, a few large names carried the index while the rest fell.

Signal Score Total 2pts

signal 2 points

Short-interest surge

Signal Score Total 2pts

signal 0 points

Selling acceleration

Signal Score Total 2pts

signal 0 points

Sentiment 90+

Signal Score Total 2pts

signal 0 points

05 · Principleas of 18:25 KST on 2026-08-28

Evening Trading Principles

A window recording the trading principles to hold to on the evening of a crash day

Market breadth turned first yesterday — the count of names moved ahead of the index

Yesterday the KOSPI index rose while 317 names advanced against 539 declining, an advance-decline ratio of 0.59. The two sessions before that read 2.86 and 2.13, with far more names rising.The count of names turned down on a day the index rose, and the index followed a day later. That ordering is not a rule — it is one instance, and there are no grounds here to join the two as cause and effect.The crash-precursor score reads 2 today, down from 3 yesterday. One item remains lit, the American depositary receipt item, and its basis is a figure from the US session of 28 July — not a signal lit by today’s data.The sentiment gauge reads 0.291, within the neutral band.