It is possible in one circumstance to have a greater loss than anticipated. Because app waits for an order fill message to place the stop loss and target orders, it could place an order entry request, and the order could be filled while the computer running the app was down. That is why is is recommended to run the app on a server or in a HA cloud environment. A home computer could be sufficient as long as it’s power plan is set up to stay awake always, and it’s plugged into an uninterruptable power supply (UPS). Another recommendation to protect your account is to have TD Ameritrade place a max loss per day on it (you have to call them to do set this up). Once you’ve reached your max loss on the day, all future orders that day will be rejected.