The Standard and Poor's Corporation (also: S&P), a subsidiary of McGraw-Hill, is a company that performs financial research and analysis. It is best known for its S&P 500 stock market index. The company also ranks the credit-worthiness of borrowers using a standardized ratings scale.

The basic ratings are:

  • AAA
  • AA
  • A
  • BBB
  • BB
  • B
  • CCC
  • CC
  • C
  • CI = past due on interest
  • D = default
  • NR

Ratings below BBB are non-investment grade junk bonds.

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