This paper proposes a network formation model of an OTC derivatives market where both prices and quantities are bilaterally negociated. The key feature of the framework is to endogenize the network of exposures, the gross and net notional amounts traded and the collateral delivered through initial and variation margins, as a function of idiosyncratic counterparty risk and regulatory collateral and clearing requirements. Using the framework, we investigate numerically the size of the derivatives network, the aggregate collateral demand and the pricing of the contracts under the following schemes: (i) various levels of collateralization for uncleared transactions, (ii) rehypothecation of received collateral and (iii) clearing through a central clearing party (CCP). Overall results suggest that dynamic effects due to the endogeneity of the derivative network to the collateralization and clearing requirements have sizeable consequences on both contract volumes and prices. Intermediary trading and market liquidity are reduced by higher collateralization requirements and enhanced by rehypothecation, while the potential for contagion is reduced. Not accounting for dynamic effects in current market conditions may lead to over-estimate collateral demand induced by mandatory central clearing by up to 22%.
