From the summer lows in June of last year to May of this year, the Junk Bond ETF (JNK) and the S&P 500 moved higher together (see green shaded area below), which, if history is a good guide, was a healthy sign.
Since May of this year, junk bonds have been creating a series of lower highs, while the S&P 500 has moved higher.
Joe Friday: "If history is a good guide, the relative weakness of junk bonds compared to the S&P 500 is sending a concerning message about stock prices in the future."