When the Show Daily P&L option is selected via the right-click Menu, you will see the Daily Profit & Loss displayed on the left-hand side of the Price Alerts Window.
The Daily Profit & Loss is based on your Price Alerts. It is calculated by comparing the current price of the stock to the Price Alert Level. The total sum of all triggered Price Alerts is displayed as the Daily Profit & Loss.
The Daily Profit & Loss shows if your Price Alert and the chosen direction, long or short, have worked in your favor or not.