Share your insights or perspective on the financial matter presented in the input.

Calculating a simply complicated return?
Since you have the balance at equal periods and the cash flows at the period ends, the best return calculation in this case is the true time-weighted return. See http://en.wikipedia.org/wiki/Time-weighted_return#Formulae  So, notwithstanding some ambiguity about your figures, here is a calculation using the first three periods from your second table. Giving a total return over the three periods of -23.88% If the periods are months, multiply by four to annualise.