Case 033Model risk and validationCore
A bank's LGD model predicts 40% for secured SME loans. A typical default in the workout data recovers 60% after three years, with collection costs at the end. Compute the realised LGD and judge the model.
1The situation
Omkarth Bank's loss given default (LGD) model predicts 40% for secured loans to small and medium businesses. You are validating it against the bank's workout records.
A typical case: a loan with Rs 100 crore outstanding at default. After three years of legal process the bank sells the collateral and recovers Rs 60 crore. It pays Rs 5 crore of legal and collection costs, all at the end. The bank discounts recoveries at 10% a year.
2Your task
What is the realised LGD on this case, how far is it from the model, and what would you conclude and recommend as the validator?
Quick check
What is the realised LGD on the typical case?
Worked solution
Try it on paper, then open one step at a time.
30-second answerThe answer to give first
The realised LGD is about 58.7%, not 40%. Net of Rs 5 crore of costs the bank recovers Rs 55 crore, but only after three years; discounted at 10% that is worth Rs 41.3 crore at default. The model's 40% equals the headline recovery exactly, which suggests it ignores both cost and time. The model fails on this evidence: expected losses are understated by about a third, and it needs recalibrating with an overlay meanwhile.
Step 1Why is a 60% recovery not a 40% loss?
Lend a friend Rs 1,000, and get Rs 600 back three years later after paying Rs 50 in reminders and bus fares. You did not lose Rs 400. You lost the Rs 50 as well, and the Rs 550 you finally got was worth less than Rs 550 would have been on the day the friend stopped paying. LGD is the economic loss measured at the date of default, so costs come off and the net recovery is discounted back. Rs 55 crore received in three years at 10% is worth Rs 55 divided by 1.1 cubed, Rs 41.3 crore.
| R | recoveries, Rs 60 crore |
| C | workout costs, Rs 5 crore |
| d | the discount rate, 10% a year |
| t | years from default to recovery, 3 |
| \text{EAD} | exposure at default, Rs 100 crore |
Step 2What does the gap tell you about the model?
The model's 40% is exactly one minus the headline recovery. That match is the clue: the model appears to have been calibrated on nominal recoveries, leaving out cost and time. The size of the error follows. Expected loss is probability of default times LGD times exposure, so an LGD of 58.7% instead of 40% raises expected loss by about 47% for every loan in the segment, and the capital and provisions built on it are short by the same proportion.
Step 3What would you check before signing the finding?
One typical case proves the method, not the calibration. Run the calculation across the whole workout sample, including curedA defaulted loan that returns to paying normally, usually with a very small loss. Leaving cures out of the sample overstates LGD. loans, which lower the average, and open cases still in court, which raise it if they are excluded. Check that losses in bad years are represented, because LGD rises when collateral values fall across a downturn. Check the discount rate too: 10% is a policy choice, and a validator reports how the answer moves if it is 8% or 12%.
The recommendation: the model fails validation for this segment. Until it is rebuilt on discounted, cost-inclusive recoveries, apply an overlay that lifts its output toward the realised level, and report the understated expected loss to the model risk committee with its capital impact.
Where candidates lose it
The usual error is to take one minus the recovery rate and say 40%, agreeing with the model. That is the same shortcut the model seems to have made.
The second is to subtract the costs but forget the three years. Time is the largest single adjustment here, Rs 13.7 crore against Rs 5 crore of costs, and it grows with every year the courts take.
What the interviewer asks next
- How would the answer change if costs were paid evenly over the three years?
- Which discount rate should an LGD model use, and why does it matter more for long workouts?
- How would you estimate LGD for a segment with very few completed workouts?
Company names and figures are illustrative.
