Relationship between futures and shares?

[JackJackJack]

Can someone explain to me the relationship between DJIA Futures and the actual DJIA value?
If I see, for example that the DJIA Index futures is currently positive at 2:31 pm does this point to a positive actual DJIA when the US market opens?

 

[Trembling Hand]

only if they stay there :

 

[MRC & Co]

Futures and cash (price of the stocks as an index) move in sync.

So if futures are up, so is cash. Has to be, as they are arbed if not, i.e. if futures move up too fast, they will be sold and stocks bought to bring them back into line and vice-versa.

So if your seeing the futures up, it means stock prices are up too (they will gap up on open), however this is dynamic and always changing, i.e. futures may fall back to to flat by the time the US opens and as such, stocks will not change value.