DislikedFrom what the guy I talked to told me here is the answers to why they trade. Depends on department. They have people who trade just trying to fill large orders at good prices by buying smaller chunks at lower prices. By them feeding them the demand and suddenly pulling it away it creates a price vaccum for price to fall back through and they can then buy more of the product at a lower price
He was in a department of pure speculating of price moves and worked off of daily and 1hr charts to find pricing points. So they traded as they found trades...Ignored