What Korean stocks did after each filing type 2026.09.21
Where this stands: of the 56 cells carrying a number, 41 have a 95% interval spanning zero. Those are not distinguishable from zero. Separately, a baseline-day cell clears zero but cannot be identified as a reaction to the filing, so it is not counted as a finding.
This is an event study of Korean stocks around DART filings — the question usually asked as how a stock reacts to an earnings filing, a rights offering or a buyback. Every filing of the types we track is joined to that company's own daily closes. The baseline is the first trading-day close on or after the receipt date; returns are then measured at +1, +5 and +20 trading days — rows forward in that stock's own series, not a calendar offset, because Korean market closures are irregular. From each return the stock's own index (KOSPI or KOSDAQ) over the identical window is subtracted. What you see is the median market-adjusted return per filing type across 2,813 filings, as of 2026.09.21. The largest sample, Periodic financial report (1446 filings), has a five-day median of -0.37% (95% CI -0.83~+0.09, spans 0), with 48% of cases beating the index. This is a record of what happened, not a claim that filings move prices and not a statement about what comes next.
Machine-readable: disclosure_impact.json · summary only (smaller) · Hugging Face dataset
| Filing type | baseline day | +1 trading day | +5 trading days | +20 trading days |
|---|---|---|---|---|
| Periodic financial report | -0.55% · 95% CI -0.7~-0.4 · beat index 40% · n=1449 | -0.41% · 95% CI -0.6~-0.3 · beat index 44% · n=1450 | -0.37% (spans 0 — not distinguishable from 0) · 95% CI -0.8~+0.1 · beat index 48% · n=1446 | +1.37% · 95% CI +0.7~+1.9 · beat index 55% · n=1412 |
| Supply contract | +0.38% (spans 0 — not distinguishable from 0) · 95% CI -0.2~+1.0 · beat index 54% · n=259 | +0.01% (spans 0 — not distinguishable from 0) · 95% CI -0.5~+0.7 · beat index 50% · n=259 | +0.82% (spans 0 — not distinguishable from 0) · 95% CI -0.3~+1.7 · beat index 54% · n=233 | -1.58% · 95% CI -5.1~-0.2 · beat index 40% · n=123 |
| Preliminary earnings (consolidated) | +0.64% (spans 0 — not distinguishable from 0) · 95% CI -0.1~+1.8 · beat index 56% · n=252 | -0.08% (spans 0 — not distinguishable from 0) · 95% CI -1.1~+1.3 · beat index 49% · n=252 | +0.43% (spans 0 — not distinguishable from 0) · 95% CI -1.3~+2.5 · beat index 53% · n=252 | -2.89% · 95% CI -4.9~-1.4 · beat index 39% · n=251 |
| Preliminary earnings (separate) | +0.76% (spans 0 — not distinguishable from 0) · 95% CI -0.3~+1.1 · beat index 55% · n=202 | -1.31% · 95% CI -2.0~-0.3 · beat index 38% · n=202 | -3.37% · 95% CI -5.0~-1.7 · beat index 36% · n=202 | -3.13% · 95% CI -4.7~-1.3 · beat index 38% · n=202 |
| Dividend decision | -0.42% (spans 0 — not distinguishable from 0) · 95% CI -1.3~+0.6 · beat index 47% · n=116 | -0.55% (spans 0 — not distinguishable from 0) · 95% CI -1.4~+0.9 · beat index 46% · n=116 | -1.12% (spans 0 — not distinguishable from 0) · 95% CI -4.0~+0.2 · beat index 43% · n=112 | -3.61% · 95% CI -7.9~-0.5 · beat index 37% · n=107 |
| Paid-in capital increase | withheld by design, n=59 | withheld by design, n=59 | withheld by design, n=49 | withheld by design, n=9 |
| Treasury stock trust contract | +4.24% · 95% CI +2.2~+5.2 · beat index 80% · n=56 | +1.96% · 95% CI +0.2~+3.4 · beat index 66% · n=56 | +3.63% · 95% CI +0.8~+8.2 · beat index 71% · n=52 | +2.34% (spans 0 — not distinguishable from 0) · 95% CI -3.7~+10.5 · beat index 59% · n=34 |
| Treasury stock trust termination | +0.89% (spans 0 — not distinguishable from 0) · 95% CI -0.0~+2.0 · beat index 61% · n=44 | -0.03% (spans 0 — not distinguishable from 0) · 95% CI -0.8~+0.7 · beat index 50% · n=44 | -0.59% (spans 0 — not distinguishable from 0) · 95% CI -3.3~+3.6 · beat index 43% · n=42 | -1.90% (spans 0 — not distinguishable from 0) · 95% CI -11.5~+9.7 · beat index 48% · n=27 |
| Convertible bond issuance | -0.58% (spans 0 — not distinguishable from 0) · 95% CI -2.1~+0.9 · beat index 48% · n=44 | -0.28% (spans 0 — not distinguishable from 0) · 95% CI -1.0~+2.0 · beat index 46% · n=44 | +0.39% (spans 0 — not distinguishable from 0) · 95% CI -2.5~+3.7 · beat index 53% · n=38 | -5.55% · 95% CI -11.4~-2.1 · beat index 19% · n=21 |
| Largest shareholder change | -0.34% (spans 0 — not distinguishable from 0) · 95% CI -2.0~+2.0 · beat index 45% · n=42 | -0.49% (spans 0 — not distinguishable from 0) · 95% CI -1.8~+0.8 · beat index 45% · n=42 | -1.74% (spans 0 — not distinguishable from 0) · 95% CI -5.9~+3.5 · beat index 34% · n=35 | -7.02% (spans 0 — not distinguishable from 0) · 95% CI -13.7~+2.0 · beat index 38% · n=21 |
| Preliminary earnings | -0.08% (spans 0 — not distinguishable from 0) · 95% CI -1.2~+2.3 · beat index 49% · n=39 | +0.12% (spans 0 — not distinguishable from 0) · 95% CI -1.3~+1.1 · beat index 51% · n=39 | -1.29% (spans 0 — not distinguishable from 0) · 95% CI -5.9~+1.9 · beat index 46% · n=37 | -7.33% · 95% CI -11.2~-2.0 · beat index 26% · n=23 |
| Treasury stock disposal | -0.88% (spans 0 — not distinguishable from 0) · 95% CI -2.0~+2.0 · beat index 46% · n=37 | -0.55% (spans 0 — not distinguishable from 0) · 95% CI -1.4~+0.4 · beat index 43% · n=37 | -0.66% (spans 0 — not distinguishable from 0) · 95% CI -4.6~+2.8 · beat index 46% · n=35 | -1.16% (spans 0 — not distinguishable from 0) · 95% CI -10.4~+13.2 · beat index 46% · n=26 |
| Treasury stock acquisition | +2.67% · 95% CI +0.2~+6.0 · beat index 71% · n=34 | +4.51% (spans 0 — not distinguishable from 0) · 95% CI -1.6~+6.0 · beat index 68% · n=34 | +4.35% (spans 0 — not distinguishable from 0) · 95% CI -1.0~+11.9 · beat index 69% · n=32 | -4.58% (spans 0 — not distinguishable from 0) · 95% CI -8.1~+2.9 · beat index 27% · n=22 |
| New facility investment | -0.87% (spans 0 — not distinguishable from 0) · 95% CI -1.9~+0.2 · beat index 36% · n=28 | -1.68% (spans 0 — not distinguishable from 0) · 95% CI -3.7~+0.6 · beat index 39% · n=28 | -2.13% (spans 0 — not distinguishable from 0) · 95% CI -5.3~+3.7 · beat index 36% · n=25 | withheld, n=17 |
| Merger | -0.38% (spans 0 — not distinguishable from 0) · 95% CI -1.5~+0.6 · beat index 33% · n=24 | +2.33% (spans 0 — not distinguishable from 0) · 95% CI -1.3~+5.9 · beat index 67% · n=24 | +3.72% (spans 0 — not distinguishable from 0) · 95% CI -1.0~+5.7 · beat index 71% · n=24 | withheld, n=9 |
| Subsidiary paid-in capital increase | +0.42% (spans 0 — not distinguishable from 0) · 95% CI -2.1~+3.4 · beat index 50% · n=22 | +0.33% (spans 0 — not distinguishable from 0) · 95% CI -2.1~+2.0 · beat index 54% · n=22 | withheld, n=19 | withheld, n=10 |
| Reverse stock split | withheld by design, n=16 | withheld by design, n=16 | withheld by design, n=12 | withheld by design, n=5 |
| Material change in profit/loss structure | withheld, n=7 | withheld, n=7 | withheld, n=7 | withheld, n=3 |
| Capital reduction | withheld, n=5 | withheld, n=5 | withheld, n=2 | not elapsed yet |
| Subsidiary capital reduction | withheld, n=4 | withheld, n=4 | withheld, n=1 | not elapsed yet |
| Subsidiary merger | withheld, n=4 | withheld, n=4 | withheld, n=4 | withheld, n=2 |
| Bonus issue | withheld by design, n=3 | withheld by design, n=3 | withheld by design, n=2 | withheld by design, n=1 |
| Subsidiary company split-off | withheld, n=2 | withheld, n=2 | withheld, n=2 | withheld, n=1 |
| Company split-off | withheld, n=2 | withheld, n=2 | withheld, n=1 | withheld, n=1 |
| Exchangeable bond issuance | withheld, n=1 | withheld, n=1 | withheld, n=1 | withheld, n=1 |
| Paid-in and bonus issue | withheld by design, n=1 | withheld by design, n=1 | withheld by design, n=1 | withheld by design, n=1 |
| Subsidiary exchangeable bond issuance | withheld, n=1 | withheld, n=1 | withheld, n=1 | withheld, n=1 |
| Subsidiary bonus issue | withheld, n=1 | withheld, n=1 | withheld, n=1 | withheld, n=1 |
| Stock split | withheld, n=1 | withheld, n=1 | withheld, n=1 | withheld, n=1 |
Withheld by design — Paid-in capital increase, Reverse stock split, Bonus issue, Paid-in and bonus issue. These filing types break the price series itself: an ex-rights date or a share consolidation resets the quoted price mechanically. Closes here are not adjusted for corporate actions, so if that date falls inside the window the number measures the break, not a market reaction. No sample size will unlock these. The individual values stay in the JSON, flagged price_break — not hidden, just not averaged.
The columns do not cover the same filings. baseline day 2026-08-03 to 2026-09-14 · +1d 2026-08-03 to 2026-09-14 · +5d 2026-08-03 to 2026-09-11 · +20d 2026-08-03 to 2026-08-21. A longer horizon excludes recent filings that have not had time to elapse, so its sample clusters earlier. If the market behaved differently across those windows, reading two columns side by side as “what happened N days later” is wrong — they are not the same set of events.
The baseline day column is the move from the previous trading
day's close into the baseline close, and it mixes filings received during the session
with those received after the close. For an after-close filing the whole baseline-day
move precedes it, so that part of this column is not a reaction. OpenDART's public API has
the receipt date only; we collect the receipt time from DART's recent-filings page and
carry it on every filing, and the baseline-day figure with after-close filings removed
is in by_session in the
summary JSON. A filing made
mid-session is already partly reflected in that day's close, and that part disappears into
the baseline. This column exists to make the missing piece visible, not to remove it.
Of the 56 cells with a number, 41 have a 95% interval spanning zero — those are not distinguishable from zero. The intervals narrow as the sample grows. A bold figure is not automatically a finding.
About the baseline-day (h0) column as a whole. Receipt times were resolved for the 2,813 filings in this table (19 unknown). The whole day follows the filing only when it arrived before the open, and that is 63 of them (2.2%). 1,251 arrived intraday, so part of the day precedes them; 1,480 arrived after the close, so the whole day precedes them. h0 is not an estimate of a reaction — it is a diagnostic column that makes the window swallowed by the baseline visible.
About the cell that clears zero — Periodic financial report · +1 trading day. The interval may move as the sample grows. n=1450, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Periodic financial report · +20 trading days. The interval may move as the sample grows. n=1412, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Supply contract · +20 trading days. The interval may move as the sample grows. n=123, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Preliminary earnings (consolidated) · +20 trading days. The interval may move as the sample grows. n=251, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Preliminary earnings (separate) · +1 trading day. The interval may move as the sample grows. n=202, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Preliminary earnings (separate) · +5 trading days. The interval may move as the sample grows. n=202, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Preliminary earnings (separate) · +20 trading days. The interval may move as the sample grows. n=202, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Dividend decision · +20 trading days. The interval may move as the sample grows. n=107, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Treasury stock trust contract · +1 trading day. The interval may move as the sample grows. n=56, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Treasury stock trust contract · +5 trading days. The interval may move as the sample grows. n=52, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Convertible bond issuance · +20 trading days. The interval may move as the sample grows. n=21, among the smallest samples here. Do not read this cell as a finding.
About the cell that clears zero — Preliminary earnings · +20 trading days. The interval may move as the sample grows. n=23, among the smallest samples here. Do not read this cell as a finding.
One exception runs the other way: Preliminary earnings (consolidated) · baseline day has a median interval spanning zero, but its beat rate of 56% has an interval of 50–62%, which excludes 50%. The size is not credible; the direction is not a coin flip. The asterisk counts medians only.
One exception runs the other way: Treasury stock acquisition · +1 trading day has a median interval spanning zero, but its beat rate of 68% has an interval of 51–81%, which excludes 50%. The size is not credible; the direction is not a coin flip. The asterisk counts medians only.
One exception runs the other way: Treasury stock acquisition · +5 trading days has a median interval spanning zero, but its beat rate of 69% has an interval of 51–82%, which excludes 50%. The size is not credible; the direction is not a coin flip. The asterisk counts medians only.
One exception runs the other way: Treasury stock acquisition · +20 trading days has a median interval spanning zero, but its beat rate of 27% has an interval of 13–48%, which excludes 50%. The size is not credible; the direction is not a coin flip. The asterisk counts medians only.
One exception runs the other way: Merger · +5 trading days has a median interval spanning zero, but its beat rate of 71% has an interval of 51–85%, which excludes 50%. The size is not credible; the direction is not a coin flip. The asterisk counts medians only.
The 95% CI shows how far the median moves with the sample (order-statistic based, no randomness, so it is identical on every publish). An interval spanning zero means that median is not distinguishable from zero — the table says so where that happens. Publishing a bold number without its interval would be the dishonest option.
Each cell is a median, not a mean — one extreme move would drag a mean around. “Beat index” is the share of cases that rose more, or fell less, than the stock's own index over the same window.
What "market-adjusted" means here — the stock's return minus its index's return, subtracted directly, which assumes beta = 1. Individual market sensitivity and size or sector effects are not removed. A KOSDAQ small cap is measured against all of KOSDAQ, so part of what is called market-adjusted here may be a size factor.
How it is computed
- Baseline = the first trading-day close on or after the filing receipt date.
- Return is taken to the close 1, 5 and 20 trading days later — trading days, not calendar days.
- The same-window return of that stock's own index (KOSPI or KOSDAQ) is subtracted. Rising 3% while the market rose 5% is underperformance, and should read as such.
- When one company files several documents on the same day, the baseline and the
price path are identical across them. Those count once per filing type.
Counting each receipt number separately inflates the sample and lets a single company's
day pull the median. The receipt count is published alongside as
n_filings. - Results are grouped by filing type and reduced to a median plus the share that beat the index.
- Amended filings are dropped — they duplicate the original. Filings whose horizon has not elapsed are excluded from that horizon only, which is why each cell carries its own n.
- Fewer than 20 observations gets no number at all. A median over a handful of cases turns coincidence into a statistic.
Questions you should ask
Did the filing cause this?
No, and nothing here claims it did. Earnings, sector moves and the market itself sit inside the same window. This is a record of what accompanied each filing type, nothing more.
Why the median instead of the mean?
One stock moving 40% would drag a mean far from the typical case. The median shows the middle case, which is what “what usually happened” should mean.
Is the stock's own index the right benchmark?
It is the honest available one, and it has a known weakness: a small-cap is compared against all of KOSDAQ, so part of what is called market-adjusted may be a size factor. Matching on size or sector would be better, but the buckets get thin at this sample size and no sector classification exists in this data. That question is open for discussion.
Can I check an individual case?
Yes. Per-filing values in the JSON are keyed by DART receipt number, so any single case can be joined back to the original document and verified.
This page is an after-the-fact tally of public data. It is not investment advice and does not recommend buying or selling any security.
What is not here
- No real-time or intraday prices. Closing prices only, published the next business day (T+1) by the government source. If you need live quotes, this is the wrong dataset.
- No target prices or analyst ratings. Those are brokerage-derived; this project
publishes only public-sector data. (PER and PBR are here where the inputs exist —
computed by us from DART financials and FSC closing prices:
valuation.pe_ttm,valuation.pbin/data/public/s/{code}.json.) - No investor-type flows (foreign / institutional / retail).
- No sector classification yet.
- Filing explanations are written in Korean. Field names and structure are English-friendly; the prose is not translated.
This site publishes public data as fact. It is not investment advice and does not recommend buying or selling any security. Source: Financial Services Commission open data portal (prices) and DART, the Financial Supervisory Service filing system. Terms: Non-commercial use with attribution; commercial redistribution is not permitted. (aiksd-public-1.1)