I apologize if I offended. Someone else asked if you had been drinking and I just suggested the supplement in case you drink. I am afraid I am too stupid to know exactly what you were after.
Overnight news and events mostly, money never sleeps, Asian and European traders are determining the price, they are equally smart and active.
They trade based on supply and demand. However if the overnight futures didnt trade, there would still be some sort of gap open most days in the cash index. So the overnight futures are the markets best estimate at any time on what the opening gap in the cash market will be.
Indexes also gap most days ... because not all the constituent parts are open exactly at 9:30am for various reasons.
Yes... and based mostly upon the reaction to "overnight news/developments" which in the minds of players might affect price. That is... some positive news overnight from anywhere, and the futures likely to bid up.. vice versa for negative news.... Japan, China, Europe raised/cut rates... loosened/tightened reserves... money-pumped into their system, etc. And of course AH reaction to earnings reports/guidance from important companies.
As you might already know, I only follow what I see on the chart. Nothing else matters. Everything else is like you say: proprietary shit.
It is called speculating. It is why stocks open gap up or down at the Wall street bell in NY every trading day at 0930 hours ET.