A heterogeneous agent model for assessing the effects of capital regulation on the interbank money market under a corridor system

Money markets play an important role in the implementation of monetary policy. Their structure and dynamics have, however, changed significantly in recent years. In particular, a number of new banking regulations will affect the behaviour of money market participants, and so have the potential to affect money market interest rates. This paper offers a model to examine how prudential regulation might affect interbank overnight interest rates where the central bank implements monetary policy using a corridor system. Combined with a set of assumptions as to the cost banks might incur in meeting regulatory capital requirements, it offers a framework with which to explore how such prudential regulation might affect the dynamics of overnight interest rates. The results — which are illustrative — estimate the interest rates at which banks might borrow and lend reserves overnight in the presence of prudential regulation. They suggest that risk-weighted capital requirements might increase the average level of overnight interbank interest rates, while the regulatory minimum leverage ratio might decrease it. If applied to real-world data on central bank reserves balances and regulatory metrics, this model also offers an insight into how central bank policymakers could — if they so choose — amend their operational frameworks to account for the effects of regulation.