Three essays on liquidity and contagion

The present PhD thesis consists of three papers. In the 1st paper we review credit risk models and models of counterparty risk and contagion and their application in credit risk management, and compare the two primary types of models in the literature that attempt to describe default processes for debt obligations and other defaultable financial instruments , usually referred to as structural and reduced-form (or intensity) models. We discuss challenges and possible progresses to be made in closing the distance between structural and reduced-form models in modeling counterparty and credit risk, mainly inside an information based perspective , in the style of Jarrow and Protter (2004). In the 2nd paper we analyses the effects of trade credit on the investment decisions of a financially constrained firms in manufacturing supply chains. We put forward a multi-factor model of a profit maximizing firm subject to bank borrowing constraints and with three sources of funding: self-financing, bank credit and trade credit. The model is able to capture the insurance effect of trade credit, i.e. the insurance coverage against liquidity risk embedded in trade credit contracts, thanks to which a financially-constrained firm suffering a liquidity shortage can maintain a level of expected inventory investment (and, as a consequence, a future expected output level) as close as possible to the optimal desired level. The 3rd paper is a paper that studies the effects that two characteristics of the topology of a financial network , namely its degrees of connectivity and of centralization, have on the response of the network to external shocks that can generate phenomena of default contagion. La presente tesis doctoral se compone de tres artículos. En el primero artículo se revisan los modelos de riesgo de crédito y los modelos de riesgo de contraparte y contagio y su aplicación en la gestión del riesgo de crédito, y se comparan los dos tipos principales de modelos en la literatura que tratan de describir los procesos predeterminados para las obligaciones de deuda y otros instrumentos financieros que son "defaultable" (que son susceptibles de incumplimiento) ; estos modelos normalmente se conocen como modelos estructurales y de forma (o intensidad) reducida. Además, se discuten los desafíos y posibles progresos a ser alcanzados al reducir la distancia entre los modelos estructurales y de forma reducida en modelar el riesgo de contraparte y riesgo de crédito, sobre todo dentro