Agency backed mortgage backed securities (MBSs) have interest
rates above Treasury rates because MBSs:
- MBSs are pool of various securities (collateralized asset)
which are subject to various factors unlike treasury
securities.
- MBSs carry risk of negative convexity and carry reinvestment
risk.
- MBSs are backed by the government sponsored agencies like FNMA
and GNMA. Therefore, they offer more returns.
- MBSsreturns are also dependent upon prepayments and
refinancing.