The Greenspan Put
Tightening aimed (indirectly, of course!) at asset bubbles will be
reversed, big time, if and when those bubbles pop.
This is the Greenspan Put !
-- Paul McCulley.
As explained at Pimco:
Put more technically, the value of the Greenspan Put will rise
exponentially if the curve inverts, while the cost of "buying"
that Put will actually become negative: in an inverted curve,
a duration-equal barbell of cash and long bonds yields more than
a bulleted portfolio. Such is the weirdness of an inverted curve:
the less volatile, convex barbell structure actually yields more
than the more volatile, less convex bullet. Rather than paying
for insurance, you get paid for taking it!