STORY: Rathbun also sees a possible warning sign for stocks coming from the bond market.
"The other thing is that there are some defaults happening in the corporate bond market," Rathbun explained. "In fact, the corporate bankruptcy rate is now the highest year-to-date since 2009. So when we see these things, it is very difficult to think that the market can continue to go up given the high valuation and the potential challenges for the fundamentals of the stock market in the rest of the year."
