Results of operations (earnings) · run dated 2026-08-14

Does the SEC's earnings filing code tell you anything about how a stock will react?

What the move actually looks like

The mechanism, before the headline number: when the move happens, whether it started early, and whether it lasts.
QuestionWhat the data says
How much lands before the open? About 55% of the typical move on the filing day happens overnight, between the previous close and the open, rather than during the trading session. By the time the market opens, most of the reaction to this kind of filing has already happened.
Did it move before the filing? +0.13% over the week before filing, against +0.12% over an earlier baseline stretch of the same earnings filings — both small next to the reaction itself, so the filing looks like the moment the information arrives.
Does the first move hold? -0.31% over the two weeks after the initial reaction, against a filing-day move of -0.15% — so the first move largely stands rather than unwinding.

These three are descriptive figures covering every filing in this category (11,235 of them), which is why their sample size differs from the validated figure below — that one is measured on the discovery slice and re-tested on two holdouts. No significance is claimed for the three above, and the pre-filing figure is shown against its own control window rather than as a finding in its own right.

The headline number

-0.15%
average abnormal return on the filing day itself, across 11,241 filings

On average, -0.15% on the filing day itself, across 11,241 filings (run dated 2026-08-14).

This is the thesis of the whole dataset in one comparison. The official code pools opposite reactions into a near-zero average; reading what the filing actually says separates them.

The figures

Average move is direction-sensitive, so opposite reactions cancel out. Typical size ignores direction and measures how big the move was either way — the two answer different questions.
WindowAverage moveTypical size of moveFilings
filing day-0.15%+6.10%11,241
filing day + 1-0.20%+6.62%11,241
filing day + 5-0.36%+7.49%11,241

The same filings, split by what they say

Both of those categories are drawn from the very filings the pooled figure above averages together.

How this was measured

This category is the official SEC item code as the company filed it. No reading of the filing text is involved, so the category rests on filing metadata alone.

For each filing we compare the stock's actual return against what that specific stock would have been expected to return given how the market moved that day. The expectation comes from the stock's own prior trading history, fitted over a window that ends well before the filing, so the filing itself cannot influence its own benchmark. The difference between actual and expected is the abnormal return, and the figures above are averages of that difference, in percentage points.

Many categories are tested at the same time, so the results are corrected for multiple comparisons. Direction and size are corrected as separate families. The windows before the filing are corrected as a family of their own. Figures from different families are not comparable to each other.

Why the holdout columns matter

A pattern found by searching a dataset will often not survive being tested on data it was not found in. Every finding on this page was discovered on one slice, frozen as a written prediction, and then tested on two untouched slices: later filings the discovery step never saw, and a separate set of companies with no overlap. A finding appears here only if it held up on both. Findings that failed this test are kept in the record and reported as refuted rather than deleted.

Limitations you should read before citing this

Cite this

Every figure on this page comes from the run named below. Quote the run date with the number.

FlinchLab. Does the SEC's earnings filing code tell you anything about how a stock will react?. Historical SEC 8-K Market-Reaction Dataset, version 0.1.0, run dated 2026-08-14. https://flinchlab.com/answers/sec-earnings-code-hides-the-reaction

Get the data

This page carries a single finding. The complete historical layer is a non-recurring, dated, versioned file. It holds every validated finding with the out-of-sample holdout columns, classification below the raw filing categories, the full aggregate grid, the data dictionary and the methodology.

Download the free sample — eight rows, all twenty columns, no email address needed. Then decide.

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What is in the file

A forward-looking version — the same classification applied to filings as they arrive — does not exist yet and has no date. If that is the one you would actually use, say so here. What people ask for is how the order of work gets decided.

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