New York

AS the job market gains steam, US Federal Reserve chairwoman Janet Yellen faces a massive challenge to adjust her monetary levers just right: she wants to keep the recovery going without stoking a bubble or spurring inflation. It's a delicate balance that has bedevilled many central bank chiefs in the past.

A dramatic drop in US bond yields over the past year might be just what Ms Yellen needs to strike that balance, according to two International Monetary Fund (IMF) economists.