Here’s the total size of the fixed income market (including money market accounts). Click to enlarge:
And here’s the annual growth rate of the fixed income market. Click to enlarge:
And here’s gross private savings. Click to enlarge:
And finally, personal saving. Click to enlarge:
Clear enough: supply and demand. Supply of fixed income instruments of all kind is flat (because private issuance, mainly private-label mortgages, has fallen while Treasury issuance has risen). Savings have jumped (as well they should).
This doesn’t count bank demand for securities, by the way. Click to enlarge:
That’s why bond yields are low.