Do Tick Charts change historical indicator values and times of bars?

Hi,

I am calculating a MACD indicator for a Tick Chart and many, many price bars after any point I care to choose, a number of the historical / previous MACD values have changed.

Does anyone know why this happens?

(For reference, I have also loaded the cTrader MACD and and my values are the same as the system generated values in both scenarios i.e. the “current” / “latest” MACD values and the previous / historical values that were different.)

Also, the same 100 tick chart will change the Start/Open time of price bars when the chart is reloaded.

I wouldn't have expected this chart behaviour as I thought that once ticks have been logged / captured, they are pretty much set (except for some “data corrections” that can be resubmitted but this is on a different scale of differences altogether).

Can anyone help please?

Thanks,

Mark