In the hours before the stock exchanges open for the day, financial news reporters often discuss the latest developments in stock index futures.
I'm curious how to interpret the developments they are discussing.
Should I interpret it as: the developments of futures are indicative of where the actual stock indices may be going? How strong is the correlation, generally?
If futures contracts on the S&P 500 fall in value, would that imply that the market believes that the market will develop more positively?
Are the stock index futures usually "rolling" or is a future for a certain upcoming contract month commonly used? How much does it matter when the future was issued?
Is there any other basic knowledge I should have when it comes to this topic? I am familiar with the concept of what a futures contract is, but I'm not entirely sure how futures relate to the interest given to the normal markets.