Spreads on corporate bonds are normally priced above the treasury note or bond of the same maturity. These spreads on yield are quoted in basis points.
1 percentage point in yield or interest rates equals 100 basis points. If the 5 year treasury note is at 4% and AA corporate bonds are priced at 50 basis points over the treasury - the yield on the bond would be 4.50%.
Spreads on corporate debt securities are different based on the rating of the bond. AAA rated fixed income debt would trade at a lower or thinner spread than a BBB rated bond - over the same treasury maturity.
Since private equity debt like corporates are of lesser credit quality than US Government securities, they will always have spreads over them. During times of lower interest rates and yields - these spreads can tighten.
Yield To Maturity
