Hi, I tried some things.
One was creating a virtual stock like mintos or grupeer and changing the value of the stock with the value of money I had in the p2p site. Not good because if you add money to the account… the value goes up but is not performance, is adding.
Secondly I tried giving to this stock the value of 1 euro and buying as much stocks as money I had in every moment… Still you cannot track the performance because if you „sell“ some stocks because you withdraw money the calculation is going to false…
At the end, I’m doing deposits/removals and interest when the money moves up and interest charge when down.