Government bonds rallied around the world as monetary policy makers in Europe, the U.K., and Canada assume more-stimulative postures amid concern that falling prices for oil and other goods pose a growing threat to economic growth.

Longer-maturity debt gained, with yields in Germany, Spain, and Switzerland reaching record lows after the European Central Bank (ECB) announcement of a larger-than-forecast bond purchase plan, the Bank of Canada's unexpected lowering of its benchmark rate, and Bank of England policy makers dropping a call for a rate increase. U.S. yields also approached all-time lows with the Federal Reserve forecast to hold interest rates at virtually zero next week.

“The central banks have been pushed to justify their existence,” said Richard Gilhooly, an interest-rate strategist in New York at Toronto-Dominion Bank's TD Securities unit, one of 22 primary dealers that trade with the Fed. “They've gone into no-man's land.”