"The point, however, is not that these are sectors of imminent stress," he writes. "The point is that these are areas that could see more dangerous mis-pricing of risk emerge in coming quarters because monetary policy is likely to remain loose, liquidity plentiful, and investors will continue to hunt for yield."

Some have argued that this mis-pricing is actually a bubble in the junk bond market.

"More to the point, these are parts of the financial system where developed market central banks would likely be unwilling or unable to ‘do whatever it takes’ to prevent a serious setback. The question would then be whether setback and stress in these sectors could be contained in a world of high leverage."

Keep an eye on the junk bond market.