SF Fed's Yellen: rates may have to burst bubbles

Janet Yellen, the president of the San Francisco Federal Reserve, has acknowledged that rate hikes may be necessary to counter asset-price bubbles, challenging a central tenet of the Greenspan-era Fed and her own previously-held views.

"I can now imagine circumstances that would justify leaning against a bubble with tighter monetary policy," said Yellen in New York on Thursday. "What has become patently obvious is that not dealing with certain kinds of bubbles before they get big can have grave