Mortgage-Backed Securities: Products, Structuring, and Analytical Techniques, 2nd Edition

Preface xi

About the Authors xv

PART ONE Introduction to Mortgage and MBS Markets 1

CHAPTER 1 Overview of Mortgages and the Consumer Mortgage Market 3

Overview of Mortgages 4

Mortgage Loan Mechanics 12

Risks Associated with Mortgages and Mortgage Products 17

Concepts Presented in this Chapter 22

CHAPTER 2 Overview of the Mortgage-Backed Securities Market 23

Creating Different Types of MBS 24

MBS Trading 35

The Role of the MBS Markets in Generating Consumer Lending Rates 40

Cash Flow Structuring 44

Concepts Presented in this Chapter 46

PART TWO Prepayment and Default Metrics and Behavior 47

CHAPTER 3 Measurement of Prepayments and Defaults 49

Prepayment Terminology 50

Calculating Prepayment Speeds 52

Delinquency, Default, and Loss Terminology 66

Concepts Presented in this Chapter 76

CHAPTER 4 Prepayments and Factors Influencing the Return of Principal 77

Prepayment Fundamentals 77

Factors Influencing Prepayment Speeds 85

Defaults and “Involuntary” Prepayments 92

Concepts Presented in this Chapter 97

PART THREE Structuring 99

CHAPTER 5  Introduction to MBS Structuring Techniques 101

Underlying Logic in Structuring Cash Flows 102

Structuring Different Mortgage Products 103

Fundamentals of Structuring CMOs 106

CHAPTER 6 Fundamental MBS Structuring Techniques: Divisions of Principal 109

Time Tranching 110

Planned Amortization Classes (PACs) and the PAC–Support Structure 116

Targeted Amortization Class Bonds 130

Z-Bonds and Accretion-Directed Tranches 130

A Simple Structuring Example 134

Concepts Presented in this Chapter 140

CHAPTER 7 Fundamental MBS Structuring Techniques: Divisions of Interest 141

Coupon Stripping and Boosting 143

Floater–Inverse Floater Combinations 147

Two-Tiered Index Bonds (TTIBs) 156

Excess Servicing IOs 160

Concepts Presented in this Chapter 166

CHAPTER 8 Structuring Private-Label CMOs 167

Private-Label Credit Enhancement 169

Private-Label Senior Structuring Variations 176

Governing Documents 189

Concepts Presented in this Chapter 191

CHAPTER 9 The Structuring of Mortgage ABS Deals 193

Fundamentals of ABS Structures 194

Credit Enhancement for Mortgage ABS Deals 199

Factors Influencing the Credit Structure of Deals 201

Additional Structuring Issues and Developments 203

Concepts Presented in this Chapter 208

PART FOUR Valuation and Analysis 209

CHAPTER 10 Techniques for Valuing MBS 211

Static Cash Flow Yield Analysis 211

Z-Spread 213

Valuation Using Monte Carlo Simulation and OAS Analysis 214

Total Return Analysis 226

Concepts Presented in this Chapter 229

CHAPTER 11 Measuring MBS Interest Rate Risk 231

Duration 231

Convexity 238

Yield Curve Risk 241

Other Risk Measures 242

Concepts Presented in this Chapter 244

CHAPTER 12 Evaluating Senior MBS and CMOs 245

Yield and Spread Matrices 246

Monte Carlo and OAS Analysis 262

Total Return Analysis 268

Evaluating Inverse Floaters 274

Concepts Presented in this Chapter 279

CHAPTER 13 Analysis of Nonagency MBS 281

Factors Impacting Returns from Nonagency MBS 281

Understanding the Evolution of Credit Performance within a Transaction 284

The Process of Estimating Private-Label MBS Returns 290

Concepts Presented in this Chapter 304

APPENDIX An Option-Theoretic Approach to Valuing MBS 305

Option-Theoretic Models for Valuing MBS 306

An Option-Based Prepayment Model for Mortgages 307

Valuation of Mortgages 311

A Closer Look At Leapers and Laggards 319

Valuation of MBS 323

Index 327