When a company, government agency or municipality issues any debt security, a credit rating is usually sought. The rating is published so investors can judge the creditworthiness of the issuer and determine more effectively the risks associated with investing in debt from that issuer. There are several credit rating agencies that provide a thorough analysis of an issuer's finances and assign a rating according to their findings. The rating is reviewed and restated quarterly in most instances, with full analysis annually for higher volume issuers.

There are three main credit rating agencies followed by investors around the globe. Moody's, Standard & Poor's and Fitch all provide objective opinions on an issuer, so investors can make wise decisions. The process of rating a bond begins with an initial meeting between an analyst at the credit rating agency and management of the issuer to go over basic financial statements of the company. Financial strength ratios are calculated to help the analyst determine the likelihood of the indenture being repaid. The initial review and rating process can take around four weeks, according to Moody's. After the analyst judges the financial strength of the company, a board of ratings analysts meets to collaborate on finding an appropriate rating for the issuer's current state. The final rating is revealed to the issuer and the public via press release.

After the initial rating, the assigned analyst keeps in contact with the issuing company's finance team and reviews its rating periodically. Ratings are most often reviewed, upgraded or downgraded each quarter, after a company releases quarterly earnings information.