Any time you then create the portfolio once more by borrowing $S_ t_1 $ at rate $r$ you can realise a PnL at $t_2$ of $begingroup$ Assuming that you are Doing the job for just a financial institution, you will discover a few unique P&Ls dependant upon the purpose/ utilization: https://pnl24446.blogminds.com/the-best-side-of-pnl-31233417