Uncertainty in the Money Supply Mechanism and Interbank Markets in Colombia
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We set a dynamic stochastic model for the interbank daily market for funds in Colombia. The framework features exogenous reserve requirements and requirement period, competitive trading among heterogeneous commercial banks, daily open market operations held by the Central Bank (auctions and window facilities), and idiosyncratic demand shocks and uncertainty in the daily auction. Analytical derivations of their decision making process show that banks involvement in the interbank market and open market operations depend on their individual requirement constraint and daily liquid assets. Our results do not show a linkage between the uncertainty in the money supply mechanism and activity in the interbank market. Equilibrium interest rate for the interbank market is derived, and is shown that it is distorted by uncertainty at the daily auction held by the monetary authority. Using data for Colombia, we test the main results of the model and corroborate the Martingale hypothesis for the interbank interest rate.
En este documento se plantea un modelo dinámico estocástico para el mercado interbancario diario en Colombia. La configuración del modelo incorpora bancos comerciales heterogéneos que interactúan en un entorno competitivo, operaciones de mercado abierto (OMA) diarias realizadas por el Banco Central (subastas y ventanillas), incertidumbre en la obtención de recursos en la subasta diaria, choques de demanda idiosincráticos y requerimientos de reserva definidos exógenamente. Las derivaciones analíticas acerca del proceso de toma de decisiones de los bancos muestran que la participación de cada entidad en el mercado interbancario y en las OMA dependen de su requerimiento de reserva y del nivel de sus activos líquidos diarios. En los resultados obtenidos no se evidencia algún vínculo entre la incertidumbre en el mecanismo de oferta monetaria y la actividad en el mercado interbancario. En particular, se encuentra la tasa de interés de equilibrio para el mercado, y se muestra que está distorsionada por la incertidumbre en la obtención de fondos en la subasta diaria. Finalmente, utilizando datos para Colombia, se prueban los principales resultados del modelo y se corrobora la hipótesis de Martingala para la tasa de interés interbancaria.
