National debt and sovereign credit ratings

In recent years South Africa’s foreign and local denominated debt has been downgraded by the three major global credit agencies, Moody’s, Standard and Poor’s (S&P) and Fitch. The foreign debt has been downgraded to speculative grade or ‘junk’ status by all three agencies. Local debt has been downgraded to ‘junk’ by S& P and Fitch, but Moody’s currently maintains local debt at the lowest level of investment grade. Many economists believe that South Africa’s rapidly rising debt levels are the major contributor to the decisions to downgrade South Africa’s debt. Yet many countries with higher levels of debt continue to be rated investment grade. Clearly, factors other than the actual level of debt are important in determining the credit rating agencies’ rating decisions. The literature suggests several variables are important in determining a country’s sovereign credit rating. These variables include not just the ratio of government debt to gross domestic product, but also a country’s real growth rate, inflation, gross domestic product per capita, external balance to gross domestic product, default history and the level of economic development. In examining the proposition that it is not a country’s debt level per se that matters, but rather the dynamics surrounding that debt, this research also includes three additional variables that are not usually mentioned in the literature. These, based on van der Merwe (1993), are the real GDP growth rate less the real interest rate, the ratio of the fiscal balance to GDP, and the ratio of government interest payments to government expenditure. The purpose of this addition is to examine whether rather than a country’s debt level (debt to GDP variable), it is the sustainability of a country’s ability to service debt, as indicated by the three additional ‘debt dynamic’ variables, that is most important when determining sovereign credit ratings. Panel data analysis for a sample of 12 countries over the period 1996Q1 to 2017Q4 indicates that of the broad macroeconomic variables mentioned in the literature, government debt to GDP, the real growth rate, inflation (cpi), and default history are all statistically significant, with the coefficients having the correct signs in all specification of the model, with the exception of the real growth rate in Models 2 and 3. With regards to the debt dynamic variables, the real growth rate less the real interest rate, as well as the interest payments to government expenditure variables are found to be significant determinants of sovereign credit ratings. Thus, the findings of the research suggest that the level of debt alone is an inadequate determinant of sovereign credit ratings. The dynamics of debt along with other macroeconomic variables are also important determinants of a country’s credit rating. Concerning policy recommendations, it is evident that debt sustainability is important for sovereign credit ratings. Evidence of the direct importance of economic growth in determining credit ratings is mixed, but growth is a key driver of debt dynamics variables and therefore of ratings. This suggests that policy should focus on stimulating growth to reduce the gap between real growth and real interest rates as well as increasing the denominator of the debt to GDP ratio and increase the size of the tax base, which would improve government’s ability to service the interest payments on its debt