The Impact of PD-LGD Correlation on Bank Capital Adequacy in Nongranular Loan Portfolio
The Central Banks discuss bank recapitalization arrangements. Markup to capital is needed because the current Basel approach is insensitive to some risks. As the Basel Committee moves from comprehensive risk modelling towards a revised, simplified, standardised approach, where one-two triggers measure risk, banking regulators increase demand for a capital add-on to meet unaccounted risks. The paper suggests the add-on estimates for the joint effect of the concentration and PD-LGD correlation risks leaving other unaccounted ones out-of-scope. The previous studies estimated add-ons for each risk separately. We show their joint impact on capital can be higher up to 5.3 times than the sum of two taken apart. Then previous results do not provide sufficient capital for a bank. We obtain that Basel underestimates the joint risk in 1.9 times on average. We expect that our contribution will be useful at least but not last for specialised lending (e.g. real estate and project finance), where the joint effect of concentration and PD-LGD correlation risks is the most observable.