The causal relationship between short- and long-term interest rates: an empirical assessment of the United States

This paper addresses one of the central aspects of the transmission mechanism of monetary policy, namely the ability of central banks to affect the structure of interest rates. To shed light on this issue, we assess the causal relationship between short- and long-term interest rates, that is, the Effective Federal Funds Rate (FF), the Moody's Seasoned Aaa Corporate Bond Yield (AAA), and the 10-Year Treasury Constant Maturity Rate (GB10Y). We apply Structural Vector Autoregressive (SVAR) models to monthly data provided by the Federal Reserve Economic Data (FRED). Our findings – estimated for the 1954-2018 period – outline an asymmetry in the relationship between short- and long-term interest rates. In particular, although we found a bidirectional relationship when the 10-year treasury bond GB10Y was included as the long-run rate, a unidirectional relationship that moves from short- to long-term interest rates is estimated when the interest rate on corporate bonds ranked AAA is taken into consideration. Furthermore, the conclusions drawn by the impulse response functions (IRFs) are confirmed and strengthened by the Forecast Error Variance Decomposition (FEVD) which shows that monetary policy is able to permanently affect long-term interest rates over a long temporal horizon, i.e., not only in the short run but also in the long run. In this way, following the Keynesian tradition, long-term interest rates appear to be strongly influenced by the central bank. Finally, despite the fact that the Federal Fund rate (FF) is weakly affected by long-term interest rate shocks, the estimated FEVD shows that FF is mainly determined by its own shock allowing us to assume that the central bank has a certain degree of freedom in setting the levels of short-run interest rates.