Abstract: In this talk, we construct a decentralized clearing mechanism which endogenously and automatically provides a claims resolution procedure.  This mechanism can be used to clear a network of obligations through blockchain.  In particular, we investigate default contagion in a network of smart contracts cleared through blockchain.  In so doing, we provide an algorithm which constructs the blockchain so as to guarantee the payments can be verified and the miners earn a fee.  We, additionally, consider the special case in which the blocks have unbounded capacity to provide a simple equilibrium clearing condition for the terminal net worths; existence and uniqueness are proven for this system.  Finally, we consider the optimal bidding strategies for each firm in the network so that all firms are utility maximizers with respect to their terminal wealths. We first look for a mixed Nash equilibrium bidding strategies, and then also consider Pareto optimal bidding strategies.  The implications of these strategies, and more broadly blockchain, on systemic risk are considered.  This is joint work with Hamed Amini and Maxim Bichuch.