Running profit/loss represents the continuously updated profit or loss on open trading positions based on current market prices. This real-time measure fluctuates constantly with price movements, providing immediate feedback on position performance. Running P&L helps traders monitor position status and make timely decisions about holding or closing positions.

Running P&L differs from realized P&L as it represents unrealized gains or losses that could change before positions are closed. Understanding running P&L helps manage trading psychology by providing objective performance measures and preventing emotional decision-making based on fear or greed.

Real-world example: A trader holding long EUR/USD positions shows +$5,000 running profit when the currency pair rises from 1.1000 to 1.1050, but this unrealized gain fluctuates continuously with exchange rate movements until positions are closed.