Federal fund futures indicate most investors think interest rates won't rise until after September 2015.

Tax payments reduce supply of short-term Treasury debt.

Traditional models fail to explain the resilience of $100 trillion market as central banks suppress short-term interest rates.

Traditional models fail to explain the resilience of $100 trillion market as central banks suppress short-term interest rates.

Cash glut overpowers Feds hints about rising rates.

Cash glut overpowers Feds hints about rising rates.

Bid-to-cover ratio for latest floater auction was 4.67, more than 50 percent higher than bid-to-cover on recent auctions of fixed-rate debt.

Bid-to-cover ratio for latest floater auction was 4.67, more than 50 percent higher than bid-to-cover on recent auctions of fixed-rate debt.