Quote from def:
Market makers, traders, brokers, etc.
Scenerio 1: Most markets are electronic. Say I have an offer on the screen of 100. A retail guy enters 99 bid. He then enters 99.5. them 99.8. I say, you had your chance now I'm 101 offer.
2: I'm a market maker, I've got an automated bid/ask in the system for a future. No trades take place but some of the components in the index tick or trade. The underlying cash increases and I just move by spread higher in relation to the fair value of the future.
3: A combo/roll market is entered in for a future. If one month ticks/trades higher, the other months will follow in order to maintain the combo prices. (ie. if I'm willing to pay 5 for the roll then a bid will be made 5 points higher in the second month off of the active front month future.
4: I make a market in 5 different futures. Say SPX and ES to make it simple. If we trade the SPX, we'll move our ES along with our SPX price.
5: Europe rallies, US moves, vice versa
6: etc.