The Mortgage-Backed Securities Workbook

The book might be old but the material is still relevant. It is considerably easier to read than most other books on mortgage products and covers prerequisite topics on top of valuation frameworks. Best resource on the topic that I have found.

This workbook was written as a companion to "Mortgage-Backed Securities" by Davidson and Herskovitz. Frankly, I think this book works much better on its own and I would recommend Fabozzi's "Handbook of Mortgage-Backed Securities" instead as a general guide to the subject. The workbook confines itself to a limited number of topics but it covers these very well. Beginning with simple cash flow and yield calculations, the authors move on to provide guidance on (simple!) prepayment modelling, basic structuring, the yield curve and regulatory tests. The approach is attractively practical, and I think of this text as a useful secret weapon to have up one's sleeve.