Is it a common practice for banks to set a minimum net gain of contract price for a secondary market loan? If management has set a net gain target, and then the bank receives a higher net gain on some loans, could that be perceived as a fair lending risk?

It could very well be. If a greater proportion of protected class applicants make up the (for example) FHA applicants and FHA is priced higher than other products without compelling and fully documented reasons, it could trigger the "effects test", a/k/a disparate impact.

HUD takes the longstanding position that liability may arise under the FHA from a racially neutral practice that has a discriminatory effect, even if there is no evidence that the practice was motivated by discriminatory intent.