Have a look at the individual default estimates per risk grade sub-category. F1 offers the highest return @ 32.26% and after that the returns decline; I guess because Harmoney has limited itself to charging under 40% and thus the loan rates are squeezed in F Grade to the extent that F2-F5 don't generate the net return warranted by the risk. They'd have to charge 50% to cover the estimated F5 default risk. That suggests that retail investors seeking to maximise return should leave F2-F5 to the wholesale players.