For futures, such as oil futures, I understand that the oil companies would be the writers of the oil futures to lock-in selling price. In this context, these oil companies have the underlying assets, namely oil and they can deliver when fulfill the contracts.
For index futures, does it work similarly? i.e., are the writers who have shares of underlying indexes? for ENQ for instance, the writers bought corresponding amount of QQQ?
Or there are two groups of people who are speculating against each other:
- long group who buys
- short group who sells