How does Monetary Policy Influence Capital Markets? Using a Threshold Regression Model

Abstract

This study indicates that the effects of interest rate changes on stock prices could be twofold and that the net effect is determined by which effect is dominant. The study employs a threshold regression model to see if, before and after the central banks cut the interest rates, there is a nonlinear relation between interest rates and the stock index. Based on traditional economic theory, stock prices should be inversely related to interest rates. However, the present study finds that as interest rates start to increase or decrease, the stock index prices are significantly and positively related to the interest rates. The changes in interest rates affect stock indexes inversely only after interest rates have crossed a certain threshold. The inverse U-shaped relationship between interest rates and stock indexes differs from the traditional wisdom. It could make interest rates more valuable in forecasting stock indexes, and it holds implications for monetary policies of central banks. To avoid the spurious regression problem, this study uses a cointegration test and an error correction model to confirm the results from the threshold regression model and finds that there is a significant cointegration relationship before and after central banks cut interest rates.