A Credit rating agency (CRA) is a company that assigns credit ratings for issuers of certain types of debt obligations, corporations and governments.
The big three credit rating agencies are Fitch Ratings, Moody's Investor Service and Standard and Poor's (S&P). All originated in the United States, although Fitch has duple headquarters in New York and London.
Moody's and S&P each control about 40%of the market. Fitch Ratings ranks third in providing ratings and has about a 14% market share, sometimes is used as an alternative to one of the other majors.