The PnL among $t$ and $T$ is definitely the sum of all incrementals PnLs. That's if we denote by $PnL_ uto v $ the PnL among instances $u$ and $v$, then $begingroup$ The pnl calculation is completed in two techniques. By definition, you value your portfolio as of nowadays, you https://www.youtube.com/watch?v=qMmsQ4kKgY4