"For example, if a stock goes up 10% up pre-market because it beats earnings, it usually stays at that price level during the day. Just because people see the p

"For example, if a stock goes up 10% up pre-market because it beats earnings, it usually stays at that price level during the day. Just because people see the price up in pre-market." 1) No, it is not just because people see the price pre-market. It is because it beat earnings. Futures are not an arbitrary marker price. 2) There is so much arbing going on that I don't agree with you.