Simple Dietz method
The simple Dietz method is a means of measuring historical investment portfolio performance, compensating for external flows into/out of the portfolio during the period. The formula for the simple Dietz return is as follows: R = B − A − C A + C / 2 {\displaystyle R={\frac {B-A-C}{A+C/2}}} where R {\displaystyle R} is the portfolio rate of return, A {\displaystyle A} is the beginning market value, B {\displaystyle B} is the ending market value, and C {\displaystyle C} is the net external inflow during the period (flows out of the portfolio are negative and flows into the portfolio are positive).