June contract will get 'locked' around 10:30 ish, so for...

June contract will get 'locked' around 10:30 ish, so for example, it can be 2000 contracts on the bid at 39 and 3000 on the ask at 41, so it never moves between 39 and 41, and expires at 40. When it expires, index futures are cash settled, so you just have to pay the loss, or receive the profit, unlike 'physical delivery' futures where you end up with a barrel of crude oil on your driveway.