In the futures market, at the end of each trading day, the margin account is adjusted to reflect the investor’s gain or loss depending upon the futures closing price. This is called Marking-to-market.
In the stockmarket - time is not money - time is time and money is money.
Often money that is just sitting can later be moved into the right situation at the right time and make a vast fortune – patience – patience.
An order that if not executed expires automatically at the end of the trading session on the day it was entered.