Once you then create the portfolio again by borrowing $S_ t_1 $ at rate $r$ you could realise a PnL at $t_2$ of $begingroup$ For an alternative with cost $C$, the P$&$L, with respect to changes on the fundamental asset selling price $S$ and volatility $sigma$, is given by PNL https://www.youtube.com/watch?v=qMmsQ4kKgY4