Credit rating agencies, also called a ratings service, provide investors with an independent evaluation and assessment of debt securities' creditworthiness but has recently catered to issuers of securities who have become their paying customers.
"Participants in the securitization industry realized that they needed to secure favorable credit ratings in order to sell structured products to investors. Investment banks therefore paid handsome fees to the rating agencies to obtain the desired ratings." Ratings were/are vital to "private-label" asset-backed securitiessuch as subprime mortgage-backed securities (MBS), and collateralized debt obligations (CDO), "CDOs squared", and "synthetic CDOs"whose "financial engineering" make them "harder to understand and to price than individual loans". A credit rating agency (CRA, also called a ratings service) is a company that assigns credit ratings, which rate a debtor's ability to pay back debt by making timely principal and interest payments and the likelihood of default. 
