Final answer:
Non-conforming loans are not sold to FNMA & FHLMC mainly because of their high-risk nature, as exemplified by subprime loans with features like low down-payments and minimal income scrutiny.
Step-by-step explanation:
Two main reasons a loan is non-conforming and not sold to Fannie Mae (FNMA) and Freddie Mac (FHLMC) are related to the subprime loans and their features which include low down-payments, minimal scrutiny of the borrower's income, and risky loan structures such as NINJA loans - No Income, No Job, or Assets. These types of loans were attractive to lenders in the mid-2000s because they could be securitized and sold off, thus the lenders did not bear the financial consequences when the borrowers defaulted. However, for a loan to be sold to FNMA & FHLMC, it must meet certain criteria which these subprime loans do not fulfill due to their high risk.