$ While in the "perform case" you liquidate the portfolio at $t_1$ realising its PnL (allow me to simplify the notation a tad) Depreciation = value originally in the yr (opening equilibrium) + purchases in the 12 months − value at the conclusion of the year (closing stability) "hitparade.ch - https://lukashnswz.blogsumer.com/33292417/5-essential-elements-for-pnl