An analysis of systemic risk in alternative securities settlement architectures

This paper compares securities settlement gross and netting architectures. It studies settlement risk arising from exogenous operational delays and compares settlement failures between the two architectures as functions of the length of the settlement interval under different market conditions. While settlement failures are non monotonically related to the length of settlement cycles under both architectures, there is no clear cut ranking of which architecture delivers greater stability. We show that while, on average, netting systems seem to be more stable than gross systems, rare events may lead to contagious defaults that could affect the all system. Furthermore netting system are very sensitive to the number and initial distribution of traded shares. JEL Classification: C6, D4, G20, O33gross and net systems, Security clearing and settlement, systemic risk

Socioeconomic Networks with Long-Range Interactions

We study a modified version of a model previously proposed by Jackson and Wolinsky to account for communicating information and allocating goods in socioeconomic networks. In the model, the utility function of each node is given by a weighted sum of contributions from all accessible nodes. The weights, parameterized by the variable $\delta$, decrease with distance. We introduce a growth mechanism where new nodes attach to the existing network preferentially by utility. By increasing $\delta$, the network structure evolves from a power-law to an exponential degree distribution, passing through a regime characterised by shorter average path length, lower degree assortativity and higher central point dominance. In the second part of the paper we compare different network structures in terms of the average utility received by each node. We show that power-law networks provide higher average utility than Poisson random networks. This provides a possible justification for the ubiquitousness of scale-free networks in the real world.Comment: 11 pages, 8 figures, minor correction

Patterns of consumption in a discrete choice model with asymmetric interactions

We study the consumption behaviour of an asymmetric network of heterogeneous agents in the framework of discrete choice models with stochastic decision rules. We assume that the interactions among agents are uniquely specified by their ``social distance'' and consumption is driven by peering, distinction and aspiration effects. The utility of each agent is positively or negatively affected by the choices of other agents and consumption is driven by peering, imitation and distinction effects. The dynamical properties of the model are explored, by numerical simulations, using three different evolution algorithms with: parallel, sequential and random-sequential updating rules. We analyze the long-time behaviour of the system which, given the asymmetric nature of the interactions, can either converge into a fixed point or a periodic attractor. We discuss the role of symmetric versus asymmetric contributions to the utility function and also that of idiosyncratic preferences, costs and memory in the consumption decision of the agents.Comment: 11 pages, 9 figures, presented at "Complex Behaviour in Economics" Aix-en-Provence 3-7 May, 2000. Minor modifications made: references added and typos corrected. This paper is a fully revised version to the one previously submitted as cond-mat/990913

Trading strategies in the Italian interbank market

Using a data set which includes all transactions among banks in the Italian money market, we study their trading strategies and the dependence among them. We use the Fourier method to compute the variance-covariance matrix of trading strategies. Our results indicate that well defined patterns arise. Two main communities of banks, which can be coarsely identified as small and large banks, emerge.Comment: 19 page

Real-world options: smile and residual risk

We present a theory of option pricing and hedging, designed to address non-perfect arbitrage, market friction and the presence of `fat' tails. An implied volatility `smile' is predicted. We give precise estimates of the residual risk associated with optimal (but imperfect) hedging.Comment: 11 pages,Latex, 5 figures (appended as uuencoded compressed tar -file

The Impact of Heterogeneous Trading Rules on the Limit Order Book and Order Flows

In this paper we develop a model of an order-driven market where traders set bids and asks and post market or limit orders according to exogenously fixed rules. The model seeks to capture a number of features suggested by recent empirical analysis of limit order data, such as; fat-tailed distribution of limit order placement from current bid/ask; fat-tailed distribution of order execution-time; fat-tailed distribution of orders stored in the order book; long memory in the signs (buy or sell) of trades. The model developed here extends the earlier one of Chiarella and Iori (2002) in several important aspects, in particular agents have heterogenous time horizons and can submit orders of sizes larger than one, determined either by utility maximisation or by a random selection procedure. We analyze the impact of chartist and fundamentalist strategies on the determination of both the placement level and the placement size, on the shape of the book, the distribution of orders at different prices, and the distribution of their execution time. We compare the results of model simulations with real market data.

Criticality in a model of banking crises

An interbank market lets participants pool the risk arising from the combination of illiquid investments and random withdrawals by depositors. But it also creates the potential for one bank's failure to trigger off avalanches of further failures. We simulate a model of interbank lending to study the interplay of these two effects. We show that when banks are similar in size and exposure to risk, avalanche effects are small so that widening the interbank market leads to more stability. But as heterogeneity increases, avalanche effects become more important. By varying the heterogeneity and connectivity across banks, the system enters a critical regime with a power law distribution of avalanche sizes.Comment: presented at the conference Application of Physics in Economic Modelling, February 8 - 10, 2001, Pragu