One of the best canary’s for the stock market is the high yield index or junk bonds. As a proxy, you can look at the SPDR Barclays High Yield Bond ETF (JNK).
At first glance JNK doesn’t look like it’s down all that much. A closer look will yield a different story.
The index made a high in May of 2013, a lower high in June of 2014 and hasn’t seen those prices since. What this tells me is that there’s trouble lurking.
Keep in mind the junk bonds can be way ahead of stocks in terms of a predictor.
Something to watch for later, nonetheless.