In other words, profits are transferred from Unrealised PnL to Realised PnL using the Mark Price. Her Entry price (avgCostPrice) is still 1,000 (this is the number you will see on the BitMEX website). He thinks ETHUSDT (Mark Price 1,000) and XBTUSDT (Mark Price 20,000) will diverge with XBTUSDT moving up more than ETHUSDT. Traders’ PnL figures are constantly changing – this is why the Mark Price is used to ensure that the unrealised PnL is calculated correctly. The Mark Price is the price at which a derivatives contract is marked for Unrealised PNL and Liquidation purposes.