THE SMART TRICK OF PNL THAT NOBODY IS DISCUSSING

Helpful seriously. How can a bank use these each day PnL calculations? All things considered the prices will swing everyday and there'll be either revenue or decline as per the calculation. So, How does a bank use these day-to-day PnL calculations? $endgroup$$begingroup$ For a possibility with value $C$, the P$&$L, with regard to modifications in t