Glad to hear you like the idea!
It is indeed a rebate paid after because of two reasons:
- We need to wait until the end of the month to see what score you have at the end of the month and
- If we didn't, this would give rise to divergences between trader and investors.
Also, it needs to be made on a look-back basis because otherwise, one could argue that we'd be incentivising traders to trade more based on their score. I.e., if you knew at the beginning of the month that you qualify, you might feel incentivised to trade more that specific month.
I hope this helps!