Yeah but, the variability of returns (ie risk) goes up as the grade increases. An expected return of 15% on a D grade is better than 15% on a E grade, you need a higher return to compensate for the higher risk. There's a difference between maximising and optimising return. Harmoney's pricing of loans should take this into account but to me feels, admittedly from a position of relative ignorance, under-cooked at the lower and upper ranges.