Stock split charts

When Apple and Tesla split what will happen to the historical charts? I can see a few options…

a) there is a massive gap down where the split happens, in this case all stats like daily, monthly % percentage changes etc & chart indicators will be out a lot and make no sense.

b) the entire history chart is wiped and start again, in this case the history is lost but is clean.

c) some other more complicated option, I’ve seen some sites ( actually divide the historical data then multiply the historical volume to allow analysis to still work on the charts.

does anyone know if there been a split of other stock on T212 and what was done with the charts?

at a deeper thought level I was wondering how google finance chart for instance would display the split

The past is adjusted to the new ratio.

Well that is how it is done, but RTX ticker begs the differ. Not identical “use case” but still causes confusion in T212 charts.

I don’t think T212 does anything well def not historical.

What it should look like is with a 10:1 is the point prior to the split is reduced by 10.


Historical rates, returns, eps and almost all other stats are recalculated for the past and adjusted. This is how it happens on everywhere else, including google charts, so I’m gonno guess T212 will follow.

correction :slight_smile:

just checked and looks like they do nothing, which I believe worthy enough for a bug report.
Someone looking at the following chart will wrongly assume the price jumped from 1$ to 16$ :slight_smile:

So in a 1:5 stock split, is it as simple as just taking the same % off historical prices?

wow that’s interesting thanks, I’ve always been wary of using T212 charts due to the incomplete history for some stocks and now will be extra careful to look at stock splits too.

Yeah where you are given 5 for 1 the historical chart is increased 5x prior the split.

For given 1 for 5 the chart is reduced 5x prior to the split.

Basically the chart should be continuous with no misleading janky sharp jumps.

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you need to adjust volume too. read how stockcharts do it…

At StockCharts, we adjust our historical price data to remove gaps caused by stock splits, dividends and distributions. That may cause our charts to look different from other services that do not perform the same adjustments.

For example, if a stock splits 2-for-1, the price is suddenly half of what it used to be, creating a large gap down on the chart. If you were unaware of the split, the chart would give you the impression that something bearish happened to the underlying company. In addition, most of the technical indicators on that chart would give sell signals because of the big drop in prices. Even though such a split is generally considered a neutral event, an unadjusted chart would contain lots of bearish signals.

In order to prevent these kinds of misleading signals from appearing on our charts, we adjust all the historical data prior to the event. In the case of a 2-for-1 split, we divide all of the historical prices for the stock by 2, then multiply all of the historical volume by 2 so that the bars prior to the split match up smoothly with the bars that appear after the split.

In addition to performing adjustments that remove large gaps caused by splits, we also adjust our historical data to remove smaller gaps caused by dividends and distributions. By making these additional adjustments, we ensure that all price movements on our charts are caused by pure market forces - that is, the forces that Technical Analysis attempts to identify.

While these adjustments are very important for accurate technical signals, they can cause problems in the following circumstances:

  1. Our adjusted historical price data cannot be used to determine the actual buy or sell price for a stock at some point in the past.

  2. Our adjusted historical price data may not match up with unadjusted data from other sources.

  3. Adjusting historical price data can cause P&F reversal points to change if “Traditional” box scaling is used (the default).

Whenever a stock’s historical data is adjusted, we add it to the list of recent adjustments on our Recent Data Adjustments page.

IMPORTANT NOTE: If you want to see an unadjusted chart for a stock, add an underscore character (“_”) to the front of the ticker symbol.

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Does the same principle apply to new share issues?

I’d love to just do stock splits and reverse stock splits at really odd values just to make it more awkward.


May 18 1964 5:4
May 18 1966 3:2
April 23 1968 2:1
May 29 1974 5:4
June 1 1979 4:1
May 28 1997 2:1
May 27 1999 2:1

I have also seen really weird ones but can’t find examples now like: 29:59 :slight_smile:

I wouldn’t have put it past elon to do something a bit crazy like that, maybe a 69:1 or something

so it looks like the splits on T212 aren’t handled well in charts, maybe now that the big guns like Apple and Tesla are splitting and potential future splits of the big players let’s hope they consider adjusting the charts (as if they didn’t have enough work to do!)

22:7 or 7:22
57:125 or 125:57


We adjust the historical data by the split adjustment factor. Some charts are not adjusted because we didn’t have this feature back then.


Thanks for the answer. Nice to know that. Cheers

Thanks @David, good to know. Can you please confirm at which date you implemented the adjustment? The ACB reverse split I posted above is from mid May 2020