Credit Risk Stress Testing of Commercial Banks in Tunisia

Stress tests of credit risk is greatly affected by data constraints in Tunisian banking system. Aiming to improve the assessment of credit risk in such conditions, we propose a model to conduct a macro stress test of credit risk for a sample of ten Tunisian commercial banks based on scenario analysis.

The approach consists first in explaining the credit risk for each bank in terms of macroeconomic and bank-specific variables through a static fixed effects model, second in a stress-testing exercise using the Monte Carlo Simulation for generating credit risk losses distributions in case of different scenarios and for determining unexpected losses for each bank.

The panel analysis applied suggests a robust negative relationship between the credit risk of bank loans and real GDP growth, with a lag response of four periods. In addition, return on assets ratio and bank size show significant negative effect on credit quality, while the net loans to total asset ratio is positively associated with it.

The credit risk stress testing results indicate that an adverse scenario of economic downturn produces increase of the frequency of the higher credit loss comparatively to the lower ones for all banks of the sample and that the estimated unexpected losses that would take place in a stress situation can be covered by available capital of these banks.