Considered among the highest quality bonds based on safety of principal and dependability of interest payments. Investment grade bonds are generally divided into four rating categories, lead by bonds issued by the most stable governments and the largest, most financially-secure corporations.
A bond rated AAA by Standard & Poor's or Aaa by Moody's considered of high quality having little risk.
These are generally regarded as high quality bonds. There are two main bond rating agencies, Standard & Poor's and Moody's. Their investment grade rating will range from, AAA/Aaa to BBB/Bbb.