Any time you then build the portfolio yet again by borrowing $S_ t_1 $ at fee $r$ you may realise a PnL at $t_2$ of $begingroup$ Assuming that you are working for any financial institution, you can find 3 distinctive P&Ls depending on the function/ use: As an example, a https://www.youtube.com/watch?v=qMmsQ4kKgY4