This is reflected in the NOB spread as it measures the difference, or spread, between T-bonds and T-notes.

FORBES: Are Bond Pros Nervous Again?

The NOB spread has stayed in a broad range since June but has made higher highs, line a.

FORBES: How Do Bond Pros Like Stocks?

In April 2012, the NOB spread formed diverged from stocks as they were peaking and this warned of the correction that lasted until early June.

FORBES: Should Bond Holders Be Worried?

The NOB spread now appears to have bottomed and the technical action of two key bond ETFs is also consistent with a further decline in yields.

FORBES: Are Bond Pros Nervous Again?