Securitisation

Securitization is the financial practice of pooling various types of contractual debt such as residential mortgages, commercial mortgages, auto loans or credit card debt obligations (or other non-debt assets which generate receivables) and selling their related cash flows to third party investors as securities, which may be described as bonds, pass-through securities, or collateralized debt obligations (CDOs). Investors are repaid from the principal and interest cash flows collected from the underlying debt and redistributed through the capital structure of the new financing. Securities backed by mortgage receivables are called mortgage-backed securities (MBS), while those backed by other types of receivables are asset-backed securities (ABS).

Critics have suggested that the complexity inherent in securitization can limit investors' ability to monitor risk, and that competitive securitization markets with multiple securitizers may be particularly prone to sharp declines in underwriting standards. Private, competitive mortgage securitization played an important role in the U.S. subprime mortgage crisis.

In addition, off-balance sheet treatment for securitizations coupled with guarantees from the issuer can hide the extent of leverage of the securitizing firm, thereby facilitating risky capital structures and leading to an under-pricing of credit risk. Off-balance sheet securitizations also played a large role in the high leverage level of U.S. financial institutions before the financial crisis, and the need for bailouts.

The granularity of pools of securitized assets can mitigate the credit risk of individual borrowers. Unlike general corporate debt, the credit quality of securitized debt is non-stationary due to changes in volatility that are time- and structure-dependent. If the transaction is properly structured and the pool performs as expected, the credit risk of all tranches of structured debt improves; if improperly structured, the affected tranches may experience dramatic credit deterioration and loss.

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