It seems likely that low two-year yields may persist for some time yet. With inflation subdued and central banks clearly wanting to be sure that the economy is recovering robustly, policy makers seem in no hurry to raise rates—a development to which two-year yields would be highly sensitive. But over time, and particularly if economic data is strong, the central-bank mantra of "lower rates for longer" should start to lose its grip on markets.

J.P. Morgan JPM forecasts two-year Treasury yields should start to move concertedly higher in the second half of the year, reaching 0.8% in December 2014, even with the Fed Funds rate remaining nailed to the floor. A sustained rise in two-year rates would be a powerful signal to investors that this time the recovery is for real—and that the days of ultra-easy money are numbered.