implicit collusion in non exclusive contracting under adverse selection this paper studies how implicit collusion may take place through simple non exclusive contracting under adverse selection when multiple buyers e g entrepreneurs with risky projects non exclusively contract with multiple firms e g banks it shows that any price schedule can be supported as equilibrium terms of trade in the market if each firm s expected prot is no less than its reservation profit firms sustain collusive outcomes through the triggering trading mechanism in which they change their terms of trade contingent only on buyers reports on the lowest average price that the deviating firm s trading mechanism would induce it suggests that a good can be overpriced in a competitive market even with fully rational traders and without firms explicit collusive agreement

financial innovation in a general equilibrium model abstract we develop a model of financial innovation in which intermediaries can issue new financial securities against collateral in the form of standard securities intermediaries have to market their innovations and marketing is costly we show that the equilibrium asset structure may exhibit redundancies as frequently observed on financial markets we give conditions for efficiency of financial innovation and show that with small innovation costs the indeterminacy of equilibrium allocations has small utility consequences journal of economic literature classification numbers d52 g10

trying to explain home bias in equities and consumption investors hold a substantially larger proportion of their wealth portfolios in domestic assets than standard portfolio theory would suggest a phenomenon called equity home bias in the absence of this bias investors would optimally diversify domestic output risk using foreign equities therefore consumption growth rates would tend to co move across countries even when output growth rates do not empirically however consumption growth rates tend to have a lower correlation across countries than do output growth rates a phenomenon i call consumption home bias in this paper i discuss these two biases and their potential relationship as suggested by the literature

discussion of allocation of transmission losses to bilateral contracts in a competitive environment and reply j bialek et al comments on the paper by f d galiana et al see ibid vol 15 no 1 p 143 50 2000 the original authors reply to the comments

financial market innovation and security design an introduction abstract the article describes in the context of theory and practice this special issue of the journal of economic theory on financial market innovation and security design the main focus is on security design in incomplete financial markets possibly with asymmetrically informed traders we first survey the general equilibrium literature which emphasizes the spanning role of securities we then provide a unified framework encompassing the literature that employs a cara guassian setting to study the impact of financial innovation on risk sharing and information aggregation journal of economic literature classification numbers g10 d52

optimal innovation of futures contracts this article presents a simple model of the innovation of new futures contracts by transaction volume maximizing futures exchanges in incomplete markets under uncertainty with mean variance preferences and proportional transactions costs we characterize the set of nash equilibria for a number of exchanges simultaneously or sequentially choosing contracts the optimal monopolistic contract design is shown to be pareto optimal an example shows the failure of pareto optimality for aparticularnash equilibrium likewise in a monopolistic multiperiod setting an example shows the failure of pareto optimality given an incentive for the exchange to induce turnover

information revelation and market incompleteness this paper introduces a theory of market incompleteness based on the information transmission role of prices and its adverse impact on the provision of insurance in financial markets we analyse a simple security design model in which the number and payoff of securities are endogenous agents have rational expectations and differ in information endowments and attitudes toward risk when markets are incomplete equilibrium prices are typically partially revealing while full relevation is attained with complete markets the optimality of complete or incomplete markets depends on whether the adverse selection effect the unwillingness of agents to trade risks when they are informationally disadvantaged is stronger or weaker than the hirshleifer effect the impossibility of trading risks that have already been resolved as new securities are issued and prices reveal more information when the hirshleifer effect dominates an incomplete set of securities is preferred by all agents and generates a higher volume of trade hirshleifer 1971 was the first to point out that revelation of information can reduce risksharing opportunities in insurance markets resulting in a welfare loss in this paper we build on hirshleifer s insight to develop a theory of endogenous market incompleteness we show that in an economy with asymmetric information in which agents learn from prices an incomplete financial structure may be optimal the reason is that less information is revealed by prices when markets are incomplete than in an otherwise identical economy with complete markets 1 paradoxically a greater degree of incompleteness may result in better risk sharing since the only risks that can be traded are those whose resolution is not common knowledge at the time of trade for the same reason incompleteness of markets may also foster a higher volume of trade the connection between security design asymmetric information trading volume and welfare in financial markets is a subtle one and it is important to isolate its various facets the efficacy of security markets in aggregating and transmitting private information depends on the characteristics of the financial structure and especially on the number of tradeable assets indeed within the rational expectations paradigm informational differences disappear in equilibrium generically when the price vector has

optimality of incomplete markets abstract in a static exchange economy where the traders initial endowments are risky the optimality of the financial structure is studied when markets are incomplete only financial structures with the same number of assets are compared a market structure is optimal when in a particular economy it yields an allocation of risks which cannot be pareto dominated through the implementation of any other market structure in a linear gaussian setup the optimal market structures are shown to span an eigenspace of a matrix which combines the risk exposures of the participants in the market approximately weighted by a measure of their risk aversions journal of economic literature classification numbers d60 g10

allocation of transmission losses to bilateral contracts in a competitive environment under open access market driven transactions have become the new independent decision variables defining the behavior of the power system understanding the impact of bilateral transactions on system losses is important to be able to allocate a loss component to each individual transaction and improve economic efficiency the theory presented here is based on the argument that it is always possible to compute the exact loss allocation corresponding to an infinitesimal bilateral transaction this leads to a set of governing differential equations whose solution yields the loss allocation for contracts of any size several examples illustrate the properties of both the proposed allocation equations and other methods the dependence of the proposed solution on the path of integration and a number of implementation issues

optimal financial market integration and security design 1 we study 2 period pure exchange capital asset pricing model capm economies with incomplete financial markets and restricted participation we characterize the optimal financial market structure and efficient innovations consisting of both the introduction of new assets and the integration of segmented markets welfare gains from innovations are maximal when the endowments of affected agents are negatively correlated uncoordinated innovations lead to efficient market structures if all assets have identical participation structure or the markets being integrated trade identical assets however coordination failure in the introduction of new assets may result when assets have participation structures that overlap only partially

the significance of the market portfolio the market portfolio is in one sense the least important portfolio to provide to investors in an j agent one period stochastic endowment economy where preferences are quadratic a social welfare minded contract designer would never create a contract that would allow trading the market portfolio even the complete set of contracts all j 1 of them which achieve a first best solution never span the market portfolio these conclusions rely on the assumption that the contract designer has perfect information about agents utilities we also show that as the contract designer s information about agents utilities becomes more imperfect the optimal contracts approach contracts that weight individual endowments in proportion to elements of eigenvectors of the variance matrix of endowments then if there is a strong enough market component to endowments a portfolio approximating the market portfolio may be the most important portfolio

modeling and pricing of block flexible electricity contracts this paper presents a model for block flexible electricity contracts bfec and focuses on pricing the bfec based on the principle of no arbitrage energy is traded in blocks according to its time duration at different block prices which is called block trading the bfec requires the buyer or the seller to schedule its trading amount and the certain block of power at each time interval the block trading needs to divide the power into several blocks the prices of each power block are obtained from market clearing price by using the autoregressive model ar n as stochastic block price model an optimal scheduling strategy can be achieved by stochastic dynamic programming the price of bfec is determined by the variables and schedule of the bfec contracts with different choices of block are studied and the simulations illustrate the block flexible electricity contracts can improve power market efficiency

mechanism design by competing sellers a dynamic model with many sellers and buyers is constructed agents failing to trade may trade in the next period an equilibrium is found where sellers hold identical auctions and buyers randomize over the sellers they visit the distribution of buyer valuations is endogenous an auction with efficient reserve is an optimal mechanism from each seller s point of view in spite of the ability of any seller to alter the distribution of buyer types participating in the seller s mechanism by altering the mechanism copyright 1993 by the econometric society

strategic financial innovation in segmented markets rohit rahi obtained his ph d in economics from stanford university in 1993 he is a reader in finance and economics and a member of the financial markets group at the london school of economics his research interests are in the theory of financial markets in particular arbitrage in segmented markets security design and asset pricing with asymmetric information and in general equilibrium theory with incomplete markets he has published articles in the review of economic studies journal of economic theory and journal of business he served a nine year term on the editorial board of the review of economic studies jean pierre zigrand is a lecturer at the london school of economics his research interests are asset pricing financial intermediation theory and general equilibrium theory any opinions expressed here are those of the authors and not necessarily those of the fmg the research findings reported in this paper are the result of the independent research of the authors and do not necessarily reflect the views of the lse

welfare gains from international risksharing abstract this paper uses consumption data to compute yet unexploited welfare gains that can be achieved through risksharing among twenty oecd countries there is both aggregate national consumption risk and nondiversifiable individual specific risk countries engage in an optimal risksharing arrangement to pool risk associated with the aggregate consumption endowment streams welfare gains are associated with reduced consumption variability and with the international pricing of the consumption streams of individual countries the paper considers the standard vnm time additive preferences as well as nonexpected utility and habit formation preferences large unexploited gains are found under all sets of preferences leading to an international risksharing puzzle

speculation and risk sharing with new financial assets while the traditional view of nancial innovation emphasizes the risk sharing role of new nancial assets belief disagreements about these assets naturally lead to speculation which represents a powerful economic force in the opposite direction this paper investigates the eect of nancial innovation on portfolio risks in an economy when both the risk sharing and the speculation forces are present financial assets provide hedging services but they are also subject to speculation because traders do not necessarily agree about their payos i de ne the average variance of traders net worths as a measure of portfolio risks for this economy and i decompose it into two components the uninsurable variance de ned as the average variance that would obtain if there were no belief disagreements and the speculative variance de ned as the residual variance that results from speculative trades based on belief disagreements financial innovation always decreases the uninsurable variance because new assets increase the possibilities for risk sharing my main result shows that nancial innovation also always increases the speculative variance this is true even if traders completely agree about the payos of new assets the intuition behind this result is the hedge more bet more eect traders use new assets to hedge their bets on existing assets which in turn enables them to place larger bets and take on greater risks my second set of results concern endogenous nancial innovation when belief disagreements are su ciently large a pro t seeking market maker introduces assets that maximize the average variance among all possible choices completely disregarding the risk sharing motive for nancial innovation my third set of results concern a calibration of the model in the context of the gdp indexed assets proposed by athanasoulis and shiller 2001 when traders have reasonable amounts of belief disagreements these assets would have the unintended consequence of increasing their consumption risks

the revelation and delegation principles in common agency games in the context of common agency adverse selection games we illustrate that the revelation principle cannot be applied to study equilibria of the multi principal games we then demonstrate that an extension of the taxation principle what we term the delegation principle can be used to characterize the set of all common agency equilibria this abstract was borrowed from another version of this item

world income components measuring and exploiting risk sharing opportunities a method is constructedfor decomposing the variance of changes in incomes in the world into components to indicate the most important risk sharing opportunities among people of the world a constant absolute risk premium carp model an intertemporal general equilibrium model of the world is presented to permit optimal contract design for a contract designer maximizing a social welfare function the optimal contracts maximize the equilibrium world real interest rate securities are defined in terms of eigenvectors of a transformed variance matrix the method is applied using penn world table data on the g 7 countries 1950

non exclusive competition in the market for lemons in order to check the impact of the exclusivity regime on equilibrium allocations we set up a simple akerlof like model in which buyers may use arbitrary taris under exclusivity we obtain the zero profit separating riley rothschilds stiglitz allocation under non exclusivity there is also a unique equilibrium allocation that involves a unique price as in akerlof 1970 these results can be applied to insurance in the dual model in yaari 1987 and have consequences for empirical tests of the existence of asymmetric information

informed traders and limit order markets abstract we consider a dynamic limit order market in which traders optimally choose whether to acquire information about the asset and the type of order to submit we numerically solve for the equilibrium and demonstrate that the market is a volatility multiplier prices are more volatile than the fundamental value of the asset this effect increases when the fundamental value has high volatility and with asymmetric information across traders changes in the microstructure noise are negatively correlated with changes in the estimated fundamental value implying that asset betas estimated from high frequency data will be incorrect

optimal futures innovation in a dynamic economy the discrete time case abstract we study the optimal futures innovation in a dynamic economy and investigate how the results obtained in a static economy should be modified due to the possibility of dynamic trading we analyze three different notions of ex ante optimality depending on the authority s ability to redistribute wealth among the investors and characterize the optimal futures innovation in each sense journal of economic literature classification numbers d52 d60 g10

a note on the specification of inter firm communication in insurance markets with adverse selection abstract this paper reconsiders the proposition due to jaynes that the rothschild stiglitz wilson insurence market with adverse selection has a nash equilibrium once the sharing of information about customers is treated endogenously as part of the game among firms the proposition is shown to be correct if and only if each firm s communication behaviour is conditioned on the set of contracts that are offered by the other firms this type of conditioning introduces a reactive element which is akin to the alternative approach of wilson

optimal design of securities under asymmetric information a firm must decide what security to sell to raise external capital to finance a profitable investment opportunity there is ex ante asymmetry of information regarding the probability distribution of cash flow generated by the investment in this setting we derive necessary and sufficient conditions for a security to be optimal uniquely optimal that is for pooling at this security to be an the unique equilibrium outcome using these conditions we show that the debt contract is uniquely optimal if and only if cash flows are ordered by strict conditional stochastic dominance finally we derive an equivalence relationship between optimal security designs and designs that minimize mispricing