Dwarf

What Does Dwarf Mean?
A slang term used to describe a pool of mortgage backed securities (MBSs) that have been issued by Fannie Mae and have a maturity of 15 years. 

Investopedia explains Dwarf
Fannie Mae is short for the Federal National Mortgage Association. It is one of the governing bodies that are able to issue MBS that are guaranteed by the U.S. government or by an independent governing body in the secondary market. The other official bodies are Freddie Mac and Ginnie Mae. Ginnie Mae has the authority to guarantee MBS issues from qualified private lenders which meet a set of stringent criteria.