Profit and Loss (PnL) is calculated using the limit price or fill price once a position is opened or closed.
At any point in time while the trade is active, your profits and losses are calculated using the mark price. The mark price is derived from an index to track the price of the underlying asset.
Once you open a position on Interdax, PnL will be shown in the positions tab. A position in a loss will be in red while a profitable position will be displayed in green.
The realised PnL shows the profit or loss of your position. The return on equity percentage (ROE%) is also displayed which is your profits (or losses) as a percentage of your used margin.
You can instantly use any profits gained from a position to leverage another trade. Trading fees are also automatically included in the realised PnL.
Example
Suppose you open a position for 50,000 BTC-PERP contracts and the price of bitcoin is 10,000 USDT. If you place a limit order to buy at 10,000 USDT and it is filled, then your position value will be 5 BTC.
If the mark price rises to 10,500 USDT, then your position value will be 12,500 USDT and your realised PnL will be 0.238 BTC (2,500 USDT). You can then use the 0.238 BTC profit from the trade to immediately open a new position. Until you exit the position, its value will be the difference between the entry price and the mark price.
You can book profits by closing the position and setting a limit order to sell 50,000 BTC-PERP contracts at 10,500 USDT. However, suppose the limit price was 10,500 USDT when your order was filled, but the mark price was 10,505 USDT, your realised profits are still 0.238 BTC or 2,500 USDT. Therefore, once you exit the trade, your profits or losses are calculated using the fill price of your order.
Balances of each cryptocurrency are isolated from one another, meaning that liquidation of bitcoin positions will not affect the balances of any other cryptocurrencies. For example, if you entered a trade that generated a profit in USDT, but also entered a losing trade on ETH, then your profits will be paid in USDT and losses deducted in ETH.
For perpetual swaps on Interdax, an interest rate is continuously calculated for each position and is deducted (or added) to your realised PnL. When interest rates are positive, long positions pay short positions, while the opposite is true when interest rates are negative.