I translate my total investment amount into virtual "units".
f.e. you start with 100.000. That's 1000 units with value 100.
Suppose the value of the portfolio rises 20%.
Total value will be 120.000 or the same 1000 "units" will have value 120.
If at that point I add 60000, I virtually buy 500 units with value 120.
So then I have total investment of 180.000, or 1500 units with value 120.
Another 10% rise would take us to 198.000, or 1500 units with value 132.
etc.
Based on the value of the units, you can calculate your total and annualised return. The system takes correctly into account the additions or extractions of capital. I suppose that's also the way funds calculate their returns.
