Bond Indices Maturities and Changing Macroeconomic Conditions: Evidence from South Africa

Abstract

This paper examines the effect of macroeconomic variables on government bond yields of different maturities under two regimes in South Africa. The study employs a Two-Stage Markov regime-switching model to analyze monthly time series data from March 2009 to October 2022. It attempts to explain variations in 1-3 year, 3-7 year, 7-12 year and +12 year government bond yields with six independent variables such as inflation, real GDP, real short-term interest rates, real long-term interest rates, real money supply, and the real Rand/Dollar exchange rate.
As a result, the study finds that the performance of government bond yields varies with market conditions, as per the adaptive market hypothesis (AMH). More specifically, the returns of the 1-3 year bond index are influenced by real GDP in a bull regime, while the performance of the 3-7 year government bond yield is affected by real GDP in a bear market condition. Additionally, the inflation growth rate influences the performance of the 7-12 year government bond yield in a bull market regime, but not in a bear regime.
It also documents that the bear market conditions prevail among selected bond index returns, with the 12-year government bond yield staying in a bull state for 12 months, while the 7-12 year government bond yield stays the longest in a bear state (19 months). These findings demonstrate that the South African bond market is affected by changing conditions. Therefore, the interaction between the macroeconomy and bond performance is better explained by AMH, and there is potential for improved explanatory power through the use of nonlinear modeling techniques.