Credit ratings are an evaluation of a debtor's ability to repay debt and likelihood of default. Credit rating agencies assign ratings to institutions that issue debt. The big three international agencies are Moody's, S&P, and Fitch. Credit ratings benefit investors by indicating risk and returns, companies by lowering borrowing costs, and financial intermediaries by aiding investment decisions. However, ratings may be inaccurate and not guarantee soundness. During the financial crisis, agencies were criticized for overrating complex securities based on risky subprime mortgages.