New Members: Be sure to confirm your email address by clicking on the link that was sent to your email inbox. You will not be able to post messages until you click that link.
Why does the "Open" price change for symbols when changing the "Period" range?
I've just noticed that when viewing the "Open" price, it is different depending on the "Period" selected. I understand that High/Low/Close would change by changing the period but shouldn't the Open be the same at 9:30 ET whether you use 5 min, 30 min, 2 hours, or daily? There are some days where the open for say the 1 hour period is not even within the daily H-L range in the daily period. I've noticed that the closer you get to the 1 min period the more accurate it becomes, however the open for the daily period can be off by as much as 2-3%.
For example, SPY : GLD yesterday (2/3/15) on a daily "period" shows an open of 1.6770 at 9:30 ET. However, if you change it to a 5 min period it shows an open of 1.6701 at 9:30 ET (which is much closer to what it actually was). That is nearly a 1/2% error. And this happens on everything that uses SYMBOL : SYMBOL format from what I can tell so far, not just SPY : GLD.
(Note: It also happens on just one SYMBOL but the error is extremely small or even non-existent compared to SYMBOL : SYMBOL. For example, GLD had an open of 121.74 for a daily period on 2/3/15, yet with a 5 min period the open is shown as 121.72, in case this provides any clues.)
Anyone know the reason why this is? Any help is much appreciated!