While I'm not as analytical this evening as earlier posters (the Merchant of Venice
bit wore me out a little
), interest rates across the real yield curve are no more constrained to move in parallel than interest rates across the nominal yield curve.
I don't have to tell you
; I hope I don't have to tell anybody
; but to be sure it is clear to anyone who might later come surfing bogleheads.org:
1) Bond funds are not bank accounts; and a short-term bond fund does not bear the same relationship to a longer-term fund that a short-term CD bears to a longer-term CD; and
2) In funds one owns shares. One does not own dollars.