I would argue that a critical step in getting ready for CECL is to review the vintage curves of the segments that have been identified. Not only do the resulting graphs provide useful information but the process itself also requires thought on how to prepare the data.
Consider the following graph of auto loan losses for different vintages of Not-A-Real-Bank bank:
While this is a highly-stylized depiction of vintage curves, its intent is to illustrate what information can be gleaned from such a graph. Consider the following:
- A clear end to the seasoning period can be determined (period 8)
- Outlier vintages can be identified (2015Q4)
- Visual confirmation that segmentation captures risk profiles (there aren’t a substantial number of vintages acting odd)
But that’s not all! To get to this graph, some important questions need to be asked about the data. For example:
- Should prepayment behavior be captured when deriving the loss rates? If so, what’s the definition of prepayment?
- At what time period should the accumulation of losses be stopped (e.g., contractual term)?
- Is there enough loss behavior to model on the loan level?
- How should accounts that renew be treated (e.g., put in new vintage)?
In conclusion, performing vintage analysis is more than just creating a picture with many different colors. It provides insight into the segments, makes one consider the data, and, if the data is appropriately constructed, positions one for subsequent analysis and/or modeling.
Jonathan Leonardelli, FRM, Director of Business Analytics for the Financial Risk Group, leads the group responsible for model development, data science, documentation, testing, and training. He has over 15 years’ experience in the area of financial risk.
 Originally I called this bank ACME Bank but when I searched to see if one existed I got this, this, and this…so I changed the name. I then did a search of the new name and promptly fell into a search engine rabbit hole that, after a while, I climbed out with the realization that for any 1 or 2 word combination I come up with, someone else has already done the same and then added bank to the end.
 You can also build vintage curves on defaults or prepayment.
CECL—Questions to Consider When Selecting Loss Methodologies
CECL—The Caterpillar to Butterfly Evolution of Data for Model Development