Corporate bonds are divided into two main categories High Grade (also called Investment Grade) and High Yield (also called Non-Investment Grade, Speculative Grade, or Junk Bonds) according to their credit rating. Bonds rated AAA, AA, A, and BBB are High Grade, while bonds rated BB and below are High Yield. This is a significant distinction as High Grade and High Yield bonds are traded by different trading desks and held by different investors.