The stock market got a lot of attention this week, but the bigger story was going on in the debt market. Here's what the spike is yields is telling us.

In the usually steady government bond market, the yield on the 10-year Treasury has risen to about 4.5 percent from less than 4 percent at the end of last week.

Investors often treat government bonds as a haven during times of market stress. Now, the opposite has occurred.