In this book, the authors provide an overview of the sub-prime mortgage securitisation process and the seven key informational frictions that arise. They discuss the ways that market participants work to minimise these frictions and speculate on how this process broke down. They continue with a complete picture of the sub-prime borrower and the sub-prime loan, discussing both predatory borrowing and predatory lending. They present the key structural features of a typical sub-prime securitisation, document how rating agencies assign credit ratings to mortgage-backed securities, and outline how these agencies monitor the performance of mortgage pools over time.