What it is:
How it works (Example):
Municipal and corporate bonds are rated by credit agencies, such as Standard & Poor's and Moody's, based on the creditworthiness of the issuer. Investment grade indicates that a bond is a safe, low-risk debt instrument on which the issuer is unlikely to default.
Ratings of BBB- or higher by Standard & Poor's or ratings of Baa3 or higher by Moody's designate a bond as investment grade. Ratings are subject to change depending of the financial health of the issuer.