I'm pondering the correct way of calculating the average return of a sequence of trades of a given stock. The simple case is well defined, if I buy X number of shares for $P1/sh and sell them for $P2/sh, then the return is P2/P1. Now, what do you do in the more complex case where I buy X1 shares for $P1/sh, sell X2 of them for $P2/sh, then buy X3 of them for $P3/sh and finally sell all that remain for $P4/sh. What is the formula to calculate the average return for that sequence of trades for that one stock? For example, do you calculate an "average" basis for the stock and the net cash flows generated from the buying & selling? Or, do you treat the sequence as individual trades and then calculate a weighted average return based on the relative of the trades? etc. Don.