Loss Severity

Loss severity, often expressed as a percentage, quantifies the portion of exposure lost after a borrower default once recoveries, sales proceeds, and liquidation costs are considered. In CMBS and CRE lending it measures the realized economic loss on a defaulted mortgage relative to outstanding principal, factoring in recovery timing, disposition expenses, and any deficiency judgments. Loss severity is a core input to credit models and stress testing because it informs expected loss calculations, reserve sizing, and the necessary level of subordination to protect senior tranche investors.

Underwriters, portfolio managers, and securitization analysts use loss severity estimates to stress-test loan pools, set pricing, and determine tranche credit support and reserve accounts. When running sensitivity analyses, practitioners model various severity scenarios to assess impacts on cash flows and tranche recoveries under different market conditions and liquidation timelines. Borrowers and sponsors should be aware that higher assumed severities can limit leverage or increase loan pricing, while lower severities may reflect stronger market fundamentals or enhanced collateral recovery prospects.

Loss severity is important because it directly affects expected and unexpected loss calculations that dictate credit enhancement, pricing, and capital allocation across a CMBS transaction. It drives how much subordinated capital is required to protect senior certificates and shapes investor return expectations in stressed environments. Accurate severity assumptions improve valuation and risk management, while understating severities can lead to inadequate buffers and unexpected losses. For lenders, servicers, and investors, monitoring realized severities over time refines underwriting standards and informs portfolio risk adjustments.