If you recently transferred to TD Ameritrade / ThinkorSwim, you may see a field called Position Equity appears under your account.
Position equity represents the current market value of your portfolio positions. In other words, it’s how much your stock portfolio is worth based on the stock price of each company combined.
If you have multiple positions, you can repeat the calculation for each stock and then add them all up.
Position Equity vs. Cash
The position equity is not the right figure to look at if you want to know how much money you have accessible in your account for trading.
Instead, look at Day Trading Buying Power, Options Buying Power, and Cash Available for Trading.
All of these options are available under your Account Info gadget in ThinkorSwim.