SOUTH AFRICAN MARKET VOLATILITY,ASYMMETRY AND RETAIL INTEREST RATES PASS‐THROUGH

The purpose of this paper is to examine the interest rate transmission mechanism for South Africa as an emerging economy in a pre‐repo and repo system. It explains how the money market rate is transmitted to the retail interest rates both in the long run and short run, and tests the symmetric and asymmetric interest rate pass‐through using the error‐correction model (ECM) and the adjusted ECM‐exponential generalised autoregressive conditional heteroscedasticity (ECM‐EGARCH) (1,1)‐M methodology. This permitted the examination of the impact of interest rate volatility, along with the leverage effect. An incomplete pass‐through is found in the short run. From the entire sample period, a symmetric adjustment is found in the deposit rate, which had upward rigidity adjustment, while an asymmetric adjustment is found in the lending rate, with a downward rigidity adjustment. All the adjustments supported the collusive pricing arrangements. According to the conditional variance estimation of the ECM‐EGARCH (1,1), negative volatility impact and leverage effect are present and influential only in the symmetric deposit interest rate adjustment process in South Africa.     

Optimal Debt and Profitability in the Trade‐Off Theory

I develop a dynamic model of leverage with tax deductible interest and an endogenous cost of default. The interest rate includes a premium to compensate lenders for expected losses in default. A borrowing constraint is generated by lenders' unwillingness to lend an amount that would trigger immediate default. When the borrowing constraint is not binding, the trade‐off theory of debt holds: optimal debt equates the marginal interest tax shield and the marginal expected cost of default. Contrary to conventional interpretation, but consistent with empirical findings, increases in current or future profitability reduce the optimal leverage ratio when the trade‐off theory holds.