IntroductionSAS Credit Risk Modelling - LGD: A to Z of LGD ModellingLoss Given Default (LGD) is the most end-to-end driven component of credit risk modelling. Unlike PD or EAD, LGD is not a single modelling step-it is a complete lifecycle that starts with raw data and ends with deployment, monitoring, and regulatory defence.Most LGD material available today focuses only on the final estimation technique. It assumes that default definition, recovery construction, discounting, write-offs, restructuring, governance, and deployment are already correct or not critical. In real banks, this assumption is wrong.LGD models fail far more often because earlier steps were incomplete or poorly designed than because of weak modelling techniques.This book exists to close that gap.SAS Credit Risk Modelling - LGD: A to Z of LGD Modelling is written to cover every step of LGD credit risk modelling from start to finish, exactly as it is performed in real banking environments.What "A to Z" Means in This Book"A to Z" in this book is literal.This book documents the entire LGD lifecycle, including steps that are rarely explained together in one place, but are routinely reviewed by validators, auditors, and regulators: LGD foundations and regulatory contextGovernance, ownership, and model lifecycleLGD-specific data architecture and source systemsDefault definition and default event constructionRecovery cashflow identification and validationRecovery timing and present-value discountingWrite-offs, collateral haircuts, and net recoveryRestructuring and forbearance treatmentObserved LGD target constructionObservation and recovery windowsLGD-specific feature engineeringBinning and variable reduction for LGDStability and leakage checksLGD modelling techniques used in banksFull SAS implementation and reproducibilityValidation, calibration, downturn LGD, and stress testingDeployment, monitoring, and recalibrationIntegration with PD, EAD, IFRS 9, and BaselA complete end-to-end bank-style case studyEvery stage that materially affects LGD outcomes is covered.Why This Book Is DifferentThis book does not isolate LGD modelling from the processes around it.It treats LGD as a system, not a formula.It explains not only how each step is done, but why banks do it that way-and what goes wrong when they don't.All examples are synthetic and fictional, but the workflows, controls, and decisions reflect real banking practice.Why This Book Uses SASLGD models in real banks are built and governed in SAS environments because of transparency, auditability, and regulator acceptance.This book therefore uses clear, production-style SAS code throughout, with no black boxes and no unexplained shortcuts.How to Read This BookThis book is designed to be read sequentially.LGD is cumulative-each step depends on earlier decisions. Skipping chapters risks misunderstanding downstream logic, just as in real LGD projects.Final NoteThis book is written for practitioners who want to understand LGD A to Z, not just how to estimate it, but how to build, validate, deploy, monitor, and defend it in real banks.Everything that follows is designed for that purpose.