$ Within the "function case" you liquidate the portfolio at $t_1$ realising its PnL (allow me to simplify the notation a tad) Depreciation = value in the beginning of your 12 months (opening equilibrium) + purchases from the year − worth at the end of the yr (closing balance) For https://pnl92456.creacionblog.com/33898922/5-simple-statements-about-pnl-explained