Threshold Effect in the Bank Lending Channel of Monetary Policy Transmission and the Role of Bank Portfolio Deterioration: A PSTR Specification in the WAEMU Zone

The objective of this paper is to analyse the influence of monetary policy on credit supply in the WAEMU zone over the period 1996-2017. The study focuses on the WAEMU countries, except for Guinea-Bissau, due to the unavailability of sufficient data. We apply the Panel Smooth Transition Regression (PSTR) model of Gonzalez et al. (2005). The results reveal the non-linearity of the link between monetary policy and credit supply. There is a threshold of credit risk exposure of 8.726% above which monetary policy loses its effectiveness. Indeed, monetary policy has a positive effect on the supply of credit when the value of the gross bank portfolio deterioration rate is less than or equal to the threshold of 8.726% and an insignificant effect above this threshold. Above this threshold, the link between monetary policy and bank credit supply is distended. In this case, it is the level of economic activity that stimulates the supply of bank credit in this area. These results indicate that the effectiveness of the monetary policy conducted by the Central Bank of West African States (BCEAO), through the bank credit channel, should take into account the level of credit risk attained by banks. Thus, the study recommends that the authorities further strengthen prudential supervision within the WAEMU.