ThetaBank has extended substantial financing to two mortgage companies, which these mortgage lenders use to...

ThetaBank's default risk assessment involves calculating the joint probability of default for the two mortgage companies and comparing it to the independent risk model.

Individual Exposure at Default (EAD):$20 million for each mortgage company.

Loss Given Default (LGD):100%

Probability of Default (PD):10% for each mortgage company.

Joint Probability of Default:5%

For independent risks, the joint probability of default for two independent events is the product of their individual probabilities:

\text{Joint Probability (Independent)} = PD_1 \times PD_2 = 0.10 \times 0.10 = 0.01 \text{ (or 1%)}

Given that ThetaBank predicts the joint probability at 5%, the independent model would have underestimated the actual probability by:

5%−1%=4%5%−1%=4%

Therefore, the underestimated probability is:

4%−2%=2%4%−2%=2%

References

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