IMF chief economist says ‘maybe' financial markets are in midst of irrational exuberance

"To some degree, asset prices are being supported by very, very low interest rates. They are supported by growth expectations that could be disappointed. Our assessment that longer-term growth rates, particularly in advanced economies, are subdued, feeds into that," Obstfeld said.

"So, our concern is simply that, if interest rates were to rise faster than expected or growth outcomes not validate these high asset prices, there could be abrupt repricing that could be disruptive."