The unprecedented amount of cash the Federal Reserve has pumped into the financial system is proving more powerful for money-market rates than Chair Janet Yellen's signals she will start turning off the spigot.

At a time when Treasury bond yields are climbing on speculation that Yellen will raise interest rates sooner than expected, the three-month London interbank offered rate is going the other way. The cost of three-month loans in dollars between banks, or Libor, fell to 0.22810 percent yesterday, setting a record low for the second straight day, according to the ICE Benchmark Administration in London.

Libor, a benchmark for more than $3 trillion of global contracts and loans, has fallen about 0.02 percentage point since the end of last year despite the Fed pulling back on its bond purchases and Yellen signaling she may raise borrowing costs next year. While yields on debt that matures in 2016 or later have increased, the shortest-term rates are sliding as investors search for a place to park their record amounts of cash and reduce interest-rate risk.