The effect of COVID-19 in estimating the South African real spot-rate curve
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Abstract
This study investigates the dynamism of different mathematical term-structure models during COVID-19 to estimate the South African real spot-rate curve. The study is based on term-structure models following Nelson-Siegel framework; and further incorporates the recalibration process on static term-structure models over different economic environments. It was found that the recalibration methodology resulted in no improvements on Linear-parametric and Cubic-splines term-structure models. However, the recalibration effect on Nelson-Siegel and Svensson models resulted in an improved fit for South African inflation-indexed spot rates even in periods of heightened market risk.
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This work (article) is licensed under a Creative Commons Attribution 4.0 International License.
References
Cai, Z. (2007). Trending time-varying coefficient time series models with serially correlated errors. Journal of Econometrics, 136(1), 163–188. https://doi.org/10.1016/j.jeconom.2005.08.004.
Carvalho, V., & Garcia, V. (2019). A cross-sectional application of the Nelson-Siegel-Svensson model to several negative yield cases. Cogent Economics and Finance, [online] 7. Available at: https://www.tandfonline.com/loi/oaef20 [Accessed 14 Jun. 2020].
Castello, O., & Resta, M. (2022). Modeling the yield curve of BRICS countries: Parametric vs. machine learning techniques. Risks, 10(2), 36. https://doi.org/10.3390/risks10020036.
Christensen, J.H.E., Diebold, F., & Rudebusch, G.D. (2008). An arbitrage-free generalized Nelson-Siegel term structure model. Econometrics Journal: Royal Economic Society, 12(3), C33–C64. https://doi.org/10.3386/w14463.
Diebold, F.X., & Li, C. (2006). Forecasting the term structure of government bond yields. Journal of Econometrics, 130(2), 337–364. https://doi.org/10.1016/j.jeconom.2005.03.005.
Gujarati, D.N., & Porter, D.C. (2009). Basic econometrics. 5th ed. USA: Mcgraw-Hill/Irwin.
Hull, J.C. (2009). Options, futures, and other derivatives. 7th ed. University of Toronto: Pearson Educational Limited.
International Monetary Fund (2020). Special series on COVID-19 debt management responses to the pandemic. [online] Available at: https://www.imf.org/~/media/Files/Publications/covid19-special-notes/en-special-series-on-covid-19-debt-management-responses-to-the-pandemic.ashx?la=en [Accessed 13 May 2021].
Johannesburg Stock Exchange (2012). The JSE zero-coupon yield curves: Methodology document. [online] Available at: https://www.jse.co.za/content/JSEIndexCalculationMethodologyandConstructionItems/The%20JSE%20Zero%20Coupon%20Yield%20Curves.pdf [Accessed 15 Feb. 2019].
Kikuchi, K., & Shintani, K. (2012). Comparative analysis of zero-coupon yield curve estimation methods using JGB price data. Institute for Monetary and Economic Studies: Bank of Japan, 30(12), 75–122. Available at: https://econpapers.repec.org/paper/imeimedps/12-e-04.htm.
Lartey, V.C., & Li, Y. (2018). Zero-coupon and forward yield curves for government of Ghana bonds. SAGE Open, 8(3), 1–15. https://doi.org/10.1177/2158244018800786.
Lyuu, Y. (2004). Financial engineering and computation: Principles, mathematics, algorithms. 2nd ed. Cambridge: Cambridge University Press.
Mashoene, M., Doorasamy, M., & Rajaram, R. (2021). The application of different term-structure models to estimate South African real spot rate curve. International Journal of Finance & Banking Studies (2147-4486), 10(3), 21–36. https://doi.org/10.20525/ijfbs.v10i3.1278.
Naidoo, E., Nkuna, M. and Steenkamp, D. (2020). Developments in debt issuance costs of South African bank. South African Reserve Bank, Working Paper Series, 2020(10). Available at: https://www.resbank.co.za/Lists/News%20and%20Publications/Attachments/10157/WP%202010 [Accessed 6 Oct. 2020].
National Treasury (2020a). Debt Management Report 2019-20. [online] investor.treasury.gov.za. Available at: http://investor.treasury.gov.za/Pages/Publications.aspx [Accessed 6 May 2021].
National Treasury (2020b). Supplementary Budget Review 2020. [online] Available at: http://www.treasury.gov.za/documents/national%20budget/2020S/budgetReview.aspx [Accessed 12 May 2021].
National Treasury (2021). Budget review 2021. [online] Available at: http://www.treasury.gov.za/documents/national%20budget/2021/default.aspx [Accessed 7 May 2021].
Nelson, C.R., & Siegel, A.F. (1987). Parsimonious modeling of yield curves. The Journal of Business, 60(4), 473–489. https://doi.org/10.1086/296409.
Papailias, F. (2021). US and EA yield curve persistence during the COVID-19 pandemic. Finance Research Letters, 2022(44), 102087. https://doi.org/10.1016/j.frl.2021.102087.
Reid, M. (2009). Isolating a measure of inflation expectations for the South African financial market using forward interest rates. South African Journal of Economics: Economic Society of South Africa, 77(30), pp.399–413. Available at: https://ideas.repec.org/p/sza/wpaper/wpapers81.html [Accessed 10 Jun. 2020].
Severino, F., Cremona, M.A., & Dadié, É. (2022). COVID-19 effects on the Canadian term structure of interest rates. Review of Economic Analysis, 14(4), 473–502. Available at: https://openjournals.uwaterloo.ca/index.php/rofea/article/view/4962 [Accessed 2 May 2023].
Svensson, L.E.O. (1994). Estimating and interpreting forward interest rates: Sweden 1992-1994. IMF Working Papers, 94(114). https://doi.org/10.5089/9781451853759.001.
Vasicek, O. (1977). An equilibrium characterization of the term structure. Journal of Financial Economics, 5(2), 177–188. https://doi.org/10.1016/0304-405x(77)90016-2.
Verbeek, M. (2017). Using linear regression to establish empirical relationships. IZA World of Labor, 336, 1–11. https://doi.org/10.15185/izawol.336.
Willmott, C.J., Matsuura, K., & Robeson, S.M. (2009). Ambiguities inherent in sums-of-squares-based error statistics. Atmospheric Environment, 43(3), 749–752. https://doi.org/10.1016/j.atmosenv.2008.10.005 .