The credit quality of the securities in a portfolio is assigned by a nationally recognized statistical rating organization (NRSRO) such as Standard & Poor’s, Moody’s, or Fitch, as an indication of an issuer’s creditworthiness. Ratings range from ‘AAA (highest) to ‘D’ (lowest). Bonds rated ‘BBB’ or above are considered investment grade. Credit ratings ‘BB’ and below are lower-rated securities. High yielding, non-investment-grade bonds involve higher risks than investment-grade bonds. Adverse conditions may affect the issuer’s ability to pay interest and principal on these securities.