Looking at the short term chart, risk premiums clearly changed in 2008. Looking at the 30 year chart should give you a keen appreciation for where this relationship has been and, more importantly, where it could go from here.
The lowest level that the spread has achieved in 30 years at the close was -241bp on march 30, 1980. The highest was 275bp on July 29, 2003.
Keith McCullough & Andrew Barber
Research Edge LLC