The Price of Protection: Derivatives, Default Risk, and Margining∗

Like many financial contracts, derivatives are subject to default risk. A very popular mechanism in derivatives markets to mitigate the risk of non-performance on contracts is margining. By attaching collateral to a contract, margining supposedly reduces default risk. The broader impacts of the different types of margins are more ambiguous, however. In this paper we develop both, a theoretical model and a simulated market model to investigate the effects of margining on trading volume, wealth, default risk, and welfare. Capturing some of the main characteristics of derivatives markets, we identify situations where margining may increase default risk while reducing welfare. This is the case, in particular, when collateral is scarce. Our results suggest that margining might have a negative effect on default risk and on welfare at times when market participants expect it to be most valuable, such as during periods o