Every quarter a company reports, and the stock does something about it. This tool takes that stock's whole record of reports and turns it into a set of answers you can actually use.
For any ticker it will tell you:
How often it gaps up and how often it gaps down, and the average size of each. AAPL has gapped up after 49 of its 80 reports and down after 31, averaging +4.24% and −4.29%.
What the stock did during the session after the gap, measured open to close. This is a separate number from the gap itself, and often points the other way.
Where it was 5, 10 and 30 days later, and by the time it reported again.
Every one of those forward readings is split two ways: by whether the gap was up or down, and by whether it was large. So you can ask what usually follows a gap up, and separately what follows a gap up as big as the one that just happened.
The rest of this tutorial is those pieces in order. It starts with the gap, because everything else is measured against it.
AAPL opened at $278.86 after closing at $271.35. The whole shaded band is a stretch of price nobody traded at, because the market was shut while it moved.
The gap, and the day after it
The gap
The earnings gap is the last price before the news against the first price after it. It is the market repricing the company while you were asleep, and by definition you could not have participated.
The gap day
The gap day column measures open to close on that first tradeable session. This is the part you could have acted on: what buyers and sellers did once the news was in front of them and the new price was on the screen.
Why the distinction earns its keep
A stock can gap up 5% and then sell off all day. The gap and the gap day would be one number if you measured close to close, and you would never see it. Splitting them is what makes the rest of the tool worth reading.
Everything further out, the 5, 10 and 30 day columns and the run to the next report, is measured from the same opening price. They answer one question: if you had bought at the first price available after the news, what happened next?
Not every company reports at the same time of day, and getting this wrong would corrupt every number on the page.
A company that reports before the open is priced in that same morning. The reaction session is the report day itself.
A company that reports after the close is priced in the following morning. The reaction session is the next trading day.
The tool checks the timing of each individual report and picks the right session for that quarter. A company that has moved its schedule over the years is handled correctly quarter by quarter.
What this buys you
It means before-open reporters are measured properly instead of being dropped or shifted a day. Banks and a good many large caps report in the morning, so a tool that assumed everyone reports after the close would either lose them or misread every gap they ever made.
The most recent quarter may read Pending
Forward columns need the sessions to have actually traded. A report from last week will show its gap and its gap day while the 30-day and next-earnings columns are still filling in.
Chapter 3
The Summary Blocks
Above the log, the page reports what has happened across every quarter it holds. On AAPL that is 80 of them.
Reading
AAPL
Gap up / gap down rate
61.3% / 38.7% (49 up, 31 down)
Average gap up
+4.24%
Average gap down
−4.29%
Biggest gap up
+9.88%, 24 April 2012
Biggest gap down
−12.37%, 22 January 2008
Measured 22 July 2026.
Then four blocks of forward numbers: after all gap ups, after large gap ups, after all gap downs, and after large gap downs. Each gives the share of quarters that finished green and the average return, at every horizon.
The pattern worth knowing about
Read the gap-day row across the two directions and something jumps out.
After a gap
Gap day green
Gap day average
By the next report
Up
39%
−0.48%
65% green, +7.24%
Down
55%
+0.34%
68% green, +3.39%
AAPL, all 80 quarters.
On the day itself the gap tends to give a little back when it was up, and recover a little when it was down. Both directions then finish the quarter green about two thirds of the time. The first session and the following months are describing different things, which is the whole reason they are separate columns.
Extremes
Four outliers are listed with their dates: the biggest gap each way, and the best and worst gap days. They are worth a look before trusting an average, because a single quarter like January 2008 drags the average gap down well below what a normal quarter looks like.
Chapter 4
The Gap Threshold
There is one control on the page. It splits every past quarter into large gaps and small ones, and it drives the two "or more" blocks.
It arrives already set to the size of the most recent gap. AAPL last gapped +2.77%, so the tool opens with the threshold at 2.77 and tells you that 32 up and 20 down gaps of that size or larger have happened before. You are looking at the reaction to a gap like the one that just happened, rather than to gaps in general.
Large gaps behave differently
After a gap up
Gap day green
10 days
By the next report
All of them
39%
59%, +1.40%
65%, +7.24%
2.77% or more
34%
66%, +1.76%
75%, +9.96%
AAPL, all 80 quarters against the 32 with a gap up of 2.77% or more.
The bigger gaps gave more back on the day, 34% green against 39%, and then did better at every horizon after it. By the next report they were green three quarters of the time.
Moving it
Raise the threshold and you are asking about rarer, larger reactions, and the sample behind the two large-gap blocks shrinks accordingly. Lower it and those blocks converge on the all-gaps blocks, because nearly every quarter qualifies. The count beside the threshold tells you how many quarters are still in the sample.
The log gives every quarter the tool holds a row of its own, and every column sorts.
Date of the report.
Earnings Gap, the overnight move from Chapter 1.
Gap Day (O→C), what the first tradeable session did.
5 Days, 10 Days, 30 Days, all measured from that session's open.
Until Next Earnings, the full run from one report to the next.
The summary blocks are the average of this table. The log is where you find out whether an average describes a consistent pattern or a couple of dramatic quarters carrying everything else.
What sorting is for
Sort by Earnings Gap and the biggest reactions in the company's record come to the top, with their aftermath beside them. That is a faster way to answer "what usually happens after a big one" than reading the summary, because you can see whether the outcomes were consistent or scattered.
Sorting by Until Next Earnings does something different: it surfaces the quarters that mattered, whatever the gap did on the day.
A row is one quarter, not one trade
Every number on a row starts from the same opening price. Reading across gives you one quarter's whole arc, from the overnight jump through to the following report.