When you set up your Live Account with TD Ameritrade, Choice Trade or other Brokerage you may notice account value differences on the Positions summary tab.
The Trade Tool Positions Account Values are tied to the Bid price (if you own a stock or option) and Ask price (if you are short a stock or option). Were you to close the position, you would receive the corresponding price – or better, since you are able to try to get a better price than Bid/Ask. This method ensures you will get at least the listed value – or better.
Choice Trade Accounts can be set up to have the price shown in the Positions Summary tied to the Bid/Ask or the default, “Last Trade Price“. Last Trade Price differs from Bid/Ask in that it shows the most recent transaction price, but does not always reflect the price you will receive if you were to buy or sell the security.
TD Ameritrade ties trade values to Mark – the point between Bid and Ask. Some trades will be closed at this price, but not all. Mark does not take into account if you own or are short a position, it is simply the halfway point between the two.