What a nightmare it’s been over recent months for those attempting to hedge interest-rate risk. After trading to 4.10% in November, benchmark MBS yields were down to 3.02% near the end of March. MBS yields then rose to 3.34% in April, before reversing lower to trade all the way down to 2.51% by late June. Yields were back up to 2.91% in mid-July – only to then reverse to a three-year low of 2.30% on September 4th. Collapsing MBS yields spur waves of refinancings, shortening the lives (“duration”) of existing MBS securities trading in the marketplace (as old MBS are replaced with new lower-yielding securities).