From the desk of FTN Financial "who owns what" data base, the company revealed the biggest buyers of term fixed-income securities, including Fannie Mae and Freddie Mac bonds, during the last five years.

And the winner is — drum roll, please — households and taxpayers investing via mutual funds and the Federal Reserve.

Coming in a close second were overseas governments and central banks — no surprise there. 

Additionally, despite the Federal Reserve purchasing a large percentage of new mortgage originations since 2009, domestic portfolios have concentrated in mortgages and corporates. 

In regards to volume, these two asset classes could easily be the first on "the firing line" rather than Treasuries, FTN suggested.

"The Fed believes it has erected a firewall against a raging bear market by holding onto a sizeable portfolio of Treasuries and mortgages. The swing vote will be households and overseas investors that look at their fixed-income portfolios as an adjunct to their overall financial goals rather than strictly as assets to be maximized," FTN Financial wrote.