the structure of financial equilibrium with exogenous yields the case of incomplete markets1 this paper presents an analysis of the structure of competitive equilibrium in a model whose principal feature is incomplete financial markets formulated in the spirit of arrow specifically the overall payoffs or returns from financial instruments are assumed to be fixed or predetermined independently of the operation of the economy and these instruments are assumed to be fewer in number than required to span all potential spot markets for commodities our main result establishes that market incompleteness generates a corresponding degree of allocation indeterminateness suppose there are n 1 spot markets but only 0 m n linearly independent financial instruments so that the deficiency in financial markets is 0 n n m n then subject to some relatively innocuous technical qualifications the set of equilibrium allocations contains a smooth n dimensional submanifold we also indicate how real indeterminacy may increase when returns for example the market price and promised interest on an ordinary bond are treated as variables rather than parameters

constrained efficiency in the neoclassical growth model with uninsurable idiosyncratic shocks we investigate the welfare properties of the one sector neoclassical growth model with uninsurable idiosyncratic shocks we focus on the notion of constrained efficiency used in the general equilibrium literature our characterization of constrained efficiency uses the first order condition of a constrained planner s problem this condition highlights the margins of relevance for whether capital is too high or too low the factor composition of income of the consumption poor using three calibrations commonly considered in the literature we illustrate that there can be either over or underaccumulation of capital in steady state and that the constrained optimum may or may not be consistent with a nondegenerate long run distribution of wealth for the calibration that roughly matches the income and wealth distribution the constrained inefficiency of the market outcome is rather striking it has much too low a steady state capital stock

public investment and social risk sharing abstract how the government uses market rates of return to discount risky public projects is intrinsic to the efficient allocation of capital and the choice of public investment policy this paper shows that social discount rates for risk can be higher than lower than or equal to private rates previous analyses which argue for one sided rules where social discount rates are always lower or equal to private rates are shown to be inappropriate in general the paper shows in a general model that the difference between the social value of a public project and its market value is determined by the social insurance value that the project has from improving risk sharing relative to the market depending on the project and degree of market imperfection this term can be positive negative or zero explaining the different possibilities for the social evaluation of risk

futures pricing in electricity markets based on stable carma spot models we present a new model for the electricity spot price dynamics which is able to capture seasonality low frequency dynamics and the extreme spikes in the market instead of the usual purely deterministic trend we introduce a non stationary independent increments process for the low frequency dynamics and model the large uctuations by a non gaussian stable carma process the model allows for analytic futures prices and we apply these to model and estimate the whole market consistently besides standard parameter estimation an estimation procedure is suggested where we t the non stationary trend using futures data with long time until delivery and a robust l 1 lter to nd the states of the carma process the procedure also involves the empirical and theoretical risk premiums which as a by product are also estimated we apply this procedure to data from the german electricity exchange eex where we split the empirical analysis into base load and peak load prices we nd an overall negative risk premium for the base load futures contracts except for contracts close to delivery where a small positive risk premium is detected the peak load contracts on the other hand show a clear positive risk premium when they are close to delivery while the contracts in the longer end also have a negative premium ams 2000 subject classications primary 60g52 62m10 91b84 secondary 60g10 60g51 91b70

relative wealth concerns and financial bubbles we present a rational general equilibrium model that highlights the fact that relative wealth concerns can play a role in explaining financial bubbles we consider a finite horizon overlapping generations model in which agents care only about their consumption though the horizon is finite competition over future investment opportunities makes agents utilities dependent on the wealth of their cohort and induces relative wealth concerns agents herd into risky securities and drive down their expected return even though the bubble is likely to burst and lead to a substantial loss agents relative wealth concerns make them afraid to trade against the crowd

idiosyncratic risk and financial policy in economies subject to uninsurable idiosyncratic risks competitive equilibrium allocations are constrained inefficient reallocations of assets support pareto superior allocations this is the case even if the asset market for the allocation of aggregate risks is complete

pricing forward contracts in power markets by the certainty equivalence principle explaining the sign of the market risk premium in this paper we provide a framework that explains how the market risk premium defined as the difference between forward prices and spot forecasts depends on the risk preferences of market players and the interaction between buyers and sellers in commodities markets this premium is an important indicator of the behavior of buyers and sellers and their views on the market spanning between short term and long term horizons we show that under certain assumptions it is possible to derive explicit solutions that link levels of risk aversion and market power with market prices of risk and the market risk premium we apply our model to the german electricity market and show that the market risk premium exhibits a term structure which can be explained by the combination of two factors firstly the levels of risk aversion of buyers and sellers and secondly how the market power of producers relative to that of buyers affects forward prices with different delivery periods

stationary pareto optimality of stochastic asset equilibria with overlapping generations abstract a way of establishing the stationary pareto optimality of asset equilibria in stochastic settings with age diversity among the agents is suggested difficulties in obtaining such results arise because agents behavior is affected by random future state variables while pareto optimality defined in terms of expected lifetime utility of representative agents conditioned on their first period state involves redistributions of consumption among agents with different histories of realized states frobenius theorem is used to establish the existence of weights for which the so weighted sum of representative agents conditional expected utilities is maximized at the asset equilibrium allocation

stochastic olg models market structure and optimality for a general class of pure exchange olg economies under uncertainty we provide a complete characterization of the efficency properties of competitive equilibria when markets are only sequentially complete and the criterion of efficency is conditional pareto optimality we also consider a particular case in which markets fail to be even sequentially complete and provide a characterization when the criterion of efficency is weakened to ex post pareto optimality

commodity trade and international risk sharing how much do financial markets matter abstract this paper evaluates the social gains from international risk sharing in some simple general equilibrium models with output uncertainty a simulation model calibrated to selected moments of u s and japanese data estimates the incremental loss from a ban on international portfolio diversification to be on the order of 0 20 percent of output per year even the theoretical gains from asset trade may disappear under alternative sets of assumptions on preferences and technology the paper argues that the small magnitude of potential trade gains may help explain the apparently inconsistent findings of empirical studies on the degree of international capital mobility

an economic approach to influence activities in organizations members of organizations spend considerable time effort and ingenuity attempting to influence decision makers such influence activities may bring benefits to the organization but they also involve real costs this essay offers an economic rationale for such influence activity as representing rational self interested behavior in the presence of informational asymmetries and an analysis of how the design of the organization s structure and policies should respond to the incentives for attempting influence it is posited that information valuable for the organization s decision making is directly available only to members of the organization who have some personal stake in the decisions these individuals may then have an incentive to try to manipulate the information they develop and provide in order to influence the resulting decisions to their benefits this can be costly both in degrading the quality of decision making and in diverting the attention and effort of the organization s members from more productive activities the organization has three different methods it can employ to discourage excessive influence activities and to encourage more directly productive uses of time and effort it can limit access to decision makers and participation in decision making it can alter its decision making criteria to favor those performing well in productive activities and it can provide direct financial incentives to encourage the desired allocation of effort it is shown that an efficiently designed organization will use such financial incentives only as a last resort instead it will always first alter its decision participation policies and decisionmaking criteria

pareto optimality and competition there is a general consensus that u s financial markets are very competitive and efficient with prices quickly reflecting the available information there is also a widespread belief that these competitive and efficient markets enable the efficient allocation of scarce capital among alternative investment opportunities this belief is not based on direct observation it is virtually impossible to obtain the data concerning the joint probability distribution of returns to all possible projects which would be required for a direct assessment of the efficiency of the resource allocations to which the market gives rise rather it is based on the well known result that perfectly competitive markets generate pareto efficient resource allocations the object of this paper is to question that conclusion to show that even with apparently competitive and efficient markets resource allocations may not be pareto efficient

factor models in the german electricity market stylized facts seasonality and calibration abstract the class of arithmetic factor models is flexible enough to model all stylized facts occurring in electricity markets including negative prices while still yielding tractable derivative prices in this paper we conduct a thorough review of the requirements and possibilities of factor models we compare different seasonality functions and study their power to deseasonalise day ahead spot prices from the epex germany austria market furthermore we introduce an alternative method to estimate mean reversion speed based on arma time series and a method to evaluate the distributional fit of the model to realised market prices which we apply to two non gaussian estimated models

fiscal rules and discretion in a world economy governments are present biased toward spending fiscal rules are deficit limits that trade off commitment to not overspend and flexibility to react to shocks we compare coordinated rules chosen jointly by a group of countries to uncoordinated rules if governments present bias is small coordinated rules are tighter than uncoordinated rules individual countries do not internalize the redistributive effect of interest rates however if the bias is large coordinated rules are slacker countries do not internalize the disciplining effect of interest rates surplus limits enhance welfare and increased savings by some countries or outside economies can hurt the rest

capital regulation and credit fluctuations we provide a rationale for imposing counter cyclical capital ratios on banks in our simple model bankers cannot pledge the entire future revenues to investors which limits borrowing in good and bad times complete markets do not sufficiently stabilize credit fluctuations as banks allocate too much borrowing capacity to good states and too little to bad states as a consequence bank credit output capital prices or wages are excessively volatile imposing a stricter capital ratio in good states corrects the misallocation of the borrowing capacity increases expected output and can be beneficial to all agents in the economy although in our economy all agents are risk neutral counter cyclical capital ratios are an effective stabilization tool to ensure this effectiveness capital ratios have to be based on ex ante equity capital as classical capital ratios can be bypassed

the future of capitalism a consideration of alternatives the article reviews three entry points into a discussion of alternatives to today s neoliberal capitalism the first examines the need for a green new deal from mostly uk based think tanks positioning the household as central to the economy posing new core values for the economy that respect the environment the social economy as well as the possibilities offered by web based technologies for new economic and political community relations the second entry point is a review of feminists search for alternatives to mainstream economics and global development processes with calls for a transition to place based socio economic practices built on the ethics of care gender justice the centrality of social reproduction and community livelihoods the last section examines the alternatives to global development and neoliberal capitalism emerging from latin america examining buen vivir intercultural pluriversal political and economic practices and lessons from latin american indigenous women and decolonial feminist movements

gender and the stability of consumption a feminist contribution to post keynesian economics alan coddington critiques post keynesians for their use of fundamental uncertainty he argues that fundamental uncertainty should also affect the consumption function undermining the case for keynesian macroeconomic policies this paper shows how contemporary feminist theory provides post keynesians with a compelling response to coddington it uses the concept of gender as an effect of heteronormativity to integrate the household the institution that undertakes consumption spending into post keynesian economics this gives us a more robust analysis of the sources of consumption stability in a world marked by the fundamental unknowability of the future

regulating capital flows to emerging markets an externality view abstract we show that capital flows to emerging market economies create externalities that differ by an order of magnitude depending on the state contingent payoff profile of the flows those with pro cyclical payoffs such as foreign currency debt generate substantial negative pecuniary externalities because they lead to large repayments and contractionary exchange rate depreciations during financial crises conversely capital flows with an insurance component such as fdi or equity are largely benign we construct an externality pricing kernel and use sufficient statistics and dsge model simulations to quantify the externalities that materialized during past financial crises we find stark differences depending on the payoff profile justifying taxes of up to 3 for dollar debt but close to zero for fdi these findings contrast with the existing literature which has suggested that policymakers should focus on reducing over borrowing rather than changing the composition of external liabilities

optimal bank regulation and fiscal capacity financial regulation is synchronized across countries despite the fact that countries vary widely in their ability to bail out their banking sector in the event of a nancial crisis this paper addresses the question of whether countries with dierent scal capacity should optimally have dierent ex ante minimum bank capital requirements in an environment with endogenously in complete markets and overinvestment because of moral hazard and pecuniary externalities i show that countries with larger scal capacity should have lower ex ante minimum bank capital require ments this result is the opposite of what one may expect given that countries with larger scal capacity often have stronger moral hazard i also show that in addition to a minimum bank capital requirement regulators in countries with strong moral hazard which are countries with a concen trated nancial sector and large scal capacity should impose a limit on the amount of liquidity pledged by nancial institutions in a crisis state this would entail restricting the amount of put options cds contracts sold by nancial institutions among other measures

stationary monetary equilibria in overlapping generations models with incomplete markets abstract the objective of this paper is to study the stationary monetary equilibria of a stochastic overlapping generations model with a general incomplete asset structure it is proved that a stationary equilibrium with a nonzero price of money generically exists and is locally isolated when there is outside money for an open set of economies there is an equilibrium with positive money prices in all states the equilibrium is also given a neat characterisation in terms of the properties of the underlying state prices with only inside money there will instead be a continuum of equilibria journal of economic literature classification numbers d52 d90 e40

a macroeconomic model with a financial sector this paper studies a macroeconomic model in which financial experts borrow from less productive agents we pursue four sets of results i the economy is prone to instability and occasionally enters volatile episodes as volatility spikes agents precautionary motive increases depressing prices even further log linear approximations fail to capture these non linear effects that can cause economies to be significantly depressed for long periods of time ii endogenous risk during volatile episodes increases asset price correlations iii financial experts impose a negative externality on each other and on the labor sector by not maintaining adequate capital cushion and funding structure iv while risk sharing within the financial sector through securitization and derivatives contracts reduces many inefficiencies it can also amlify systemic risks

moral hazard and nonmarket institutions dysfunctional crowding out or peer monitoring the authors examine a situation in which insurance is characterized by moral hazard when market insurance is provided supplementary mutual assistance between family and friends unobservable to market insurers will occur when nonmarket insurers have no better information than market insurers the mutual assistance not only crowds out market insurance but is also harmful and therefore dysfunctional alternatively when nonmarket insurers can observe each other s effort perfectly mutual assistance is beneficial these results point to the potential importance of peer monitoring mechanisms in mitigating moral hazard copyright 1991 by american economic association

a reconsideration of minsky s financial instability hypothesis the worst and longest depressions have tended to occur after periods of prolonged and reasonably stable prosperity this results in part from agents rationally updating their expectations during good times and hence becoming more optimistic about future economic prospects investors then increase their leverage and shift their portfolios towards projects that would previously have been considered too risky so when a downturn does eventually occur the financial crisis and the extent of default become more severe whereas a general appreciation of this syndrome dates back to minsky 1992 jerome levy economics institute wp 74 and even beyond to irving fisher 1933 econometrica 1 337 357 we model it formally in addition endogenous default introduces a pecuniary externality since investors do not factor in the impact of their decision to take risk and default on the borrowing cost we explore the relative advantages of alternative regulations in reducing financial fragility and suggest a novel criterion for improvement of aggregate welfare

credit wages and bankruptcy laws we analyze how bankruptcy laws affect the general equilibrium interactions between credit and wages soft laws reduce the frequency of liquidations and thus ex post inefficiencies but they worsen credit rationing ex ante this hinders firm creation and thus depresses labor demand rich agents who need few outside funds can invest even if creditor rights are weak hence they favor soft laws that exclude poorer agents from the credit market and reduce the competition for labor such laws can generate greater utilitarian welfare than under perfect contract enforcement by barring access to credit to some agents soft laws lower wages which increases the pledgeable income of richer agents and decreases the liquidation rates they must commit to when they induce strong credit rationing however soft laws are pareto dominated by tougher laws combined with subsidies to entrepreneurs

short term variations and long term dynamics in commodity prices in this article we develop a two factor model of commodity prices that allows meanreversion in short term prices and uncertainty in the equilibrium level to which prices revert although these two factors are not directly observable they may be estimated from spot and futures prices intuitively movements in prices for long maturity futures contracts provide information about the equilibrium price level and differences between the prices for the short and long term contracts provide information about short term variations in prices we show that although this model does not explicitly consider changes in convenience yields over time this short term long term model is equivalent to the stochastic convenience yield model developed in gibson and schwartz 1990 we estimate the parameters of the model using prices for oil futures contracts and apply the model to some hypothetical oil linked assets to demonstrate its use and some of its advantages over the gibson schwartz model

managing credit booms and busts a pigouvian taxation approach we study a dynamic model in which the interaction between debt ac cumulation and asset prices magni es credit booms and busts we nd that borrowers do not internalize these feedback eects and therefore suf fer from excessively large booms and busts in both credit ows and asset prices we show that a pigouvian tax on borrowing may induce borrowers to internalize these externalities and increase welfare we calibrate the model by reference to i the us small and medium sized enterprise sector and ii the household sector and nd the optimal tax to be countercycli cal in both cases dropping to zero in busts and rising to approximately half a percentage point of the amount of debt outstanding during booms

decentralization duplication and delay we argue that although decentralization has advantages in finding low cost solutions these advantages are accompanied by coordination problems which lead to delay or duplication of effort or both consequently decentralization is desirable when there is little urgency or a great deal of private information but it is strictly undesirable in urgent problems when private information is less important we also examine the effect of large numbers and find that coordination problems disappear in the limit if distributions are common knowledge

procrastination and obedience in this lecture i shall focus on situations involving repeated decisions with time inconsistent behavior although each choice may be close to maximizing and therefore result in only small losses the cumulative effect of a series of repeated errors may be quite large thus in my examples decision makers are quite close to the intelligent well informed individuals usually assumed in economic analysis but cumulatively they make seriously wrong decisions that do not occur in standard textbook economics this lecture discusses and illustrates several pathological modes of individual and group behavior procrastination in decision making undue obedience to authority membership of seemingly normal individuals in deviant cult groups and escalation of commitment to courses of action that are clearly unwise in each case individuals choose a series of current actions without fully appreciating how those actions will affect future perceptions and behavior the standard assumption of rational forwardlooking utility maximizing is violated the nonindependence of errors in decision making in the series of decisions can be explained with the concept from cognitive psychology of undue salience or vividness for example present benefits and costs may have undue salience relative to future costs

stochastic equilibria with incomplete financial markets abstract we demonstrate the existence of equilibria with incomplete financial markets for stochastic economies whose information structure is given by an event tree restricting attention to purely financial securities those paying in units of account e g dollars financial markets may be incomplete some consumption streams may be impossible to obtain by any trading strategy securities may be individually precluded from trade at arbitrary states and dates sufficient conditions for the existence of stochastic equilibria are continuous convex strictly monotonic preferences and strictly positive aggregate endowments these conditions are weakened a corollary states that any regime of security prices precluding arbitrage can be embedded in an equilibrium

shifting foundations of agricultural policy analysis welfare economics when risk markets are incomplete the neat alignment of resources output and prices specified by the perfect competition model is far from duplicated in free markets and the equally neat alignment assumed under the constraints of a program is not experienced when programs are in effect in particular areas under empirically determined supply curves are unlikely to represent opportunity costs the basic theory is invaluable in providing a conceptual orientation for the analysis of programs but the assumptions implicit in the literal use of simple forms of it for policy conclusions are breathtakingly heroic

a model of financial market liquidity based on intermediary capital we present a model ofnancial market liquidity provided bynanciallyconstrained inter mediaries we show that market liquidity increases with the level of intermediary capital we also characterize conditions under which intermediaries play a stabilizing or destabi lizing role in markets finally we sketch a number of areas including welfare and public policy on which the model can shed light jel g01 g11 g12 g15 g18

equilibrium in economies with incomplete financial markets abstract this paper analyses an exchange economy in the absence of arrow debreu complete markets it is assumed that trading takes place in the sequence of spot markets and futures markets for securities payable in units of account unlimited short selling in securities is allowed a general equilibrium in such an economy is a set of current and future prices contingent on uncertain events and a set of individual plans such that all markets are cleared the existence of such an equilibrium is proved under usual assumptions this is in contrast to the case of futures markets for contingent futures commodities where an equilibrium may not exist the optimality of equilibrium allocations is also discussed

pecuniary externalities in economies with financial frictions this article characterizes the efficiency properties of competitive economies with financial constraints in which phenomena such as fire sales and financial amplification may arise we show that financial constraints lead to two distinct types of pecuniary externalities distributive externalities that arise from incomplete insurance markets and collateral externalities that arise from price dependent financial constraints for both types of externalities we identify three sufficient statistics that determine optimal taxes on financing and investment decisions to implement constrained efficient allocations we also show that fire sales and financial amplification are neither necessary nor sufficient to generate inefficient pecuniary externalities we demonstrate how to employ our framework in a number of applications whereas collateral externalities generally lead to over borrowing the distortions from distributive externalities may easily flip sign leading to either under or over borrowing both types of externalities may lead to under or over investment

estimating the commodity market price of risk for energy prices the purpose of this paper is to estimate the market price of risk mpr for energy commodities the ratio of expected return to standard deviation the mpr sign determines whether energy forward prices are upward or downward biased predictors of expected spot prices we estimate mprs using spot and futures prices while accounting for the samuelson effect we find long term mprs generally positive and short term negative consistent with positive energy betas and hedging respectively in spot electricity markets mprs in day ahead prices agree with short dated futures our results relate risk premia to informed hedging decisions and futures prices to forecast expected prices

pricing of forwards and other derivatives in cointegrated commodity markets abstract we analyze cointegration in commodity markets and propose a parametric class of pricing measures which preserves cointegration for forward prices with fixed time to maturity we present explicit expressions for the term structure of volatility and correlation in the context of our spot price models based on continuous time autoregressive moving average dynamics for the stationary components the term structures have many interesting shapes and we provide some empirical evidence from refined oil future prices at nymex defending our modeling idea motivated from these results we present a cointegrated forward price dynamics using the heath jarrow morton approach in this setting the concept of cointegration is extended to what we call cointegration in the limit which is an asymptotic form of the notion the margrabe formula for spread option prices is shown to hold with an explicit plug in volatility we present several numerical examples showing that cointegration leads to significantly cheaper spread options compared to the complete market case where cointegration disappears with respect to the pricing measure

contractual externalities and systemic risk we study effort and risk taking behaviour in an economy with a continuum of principal agent pairs where each agent exerts costly hidden effort principals write contracts based on both absolute and relative performance evaluations ape and rpe respectively to make individually optimal risk return trade offs but do not take into account their impact on endogenously determined aggregate variables this results in contractual externalities when these aggregate variables are used as benchmarks in contracts contractual externalities have welfare changing effects when principals put too much weight on ape or rpe due to information frictions relative to the second best if the expected productivity is high risk averse principals over incentivize their own agents triggering a rat race in effort exertion resulting in over investment in effort and excessive exposure to industry risks the opposite occurs when the expected productivity is low inducing pro cyclical investment and risk taking behaviours

real indeterminacy with financial assets abstract it is shown that in a two period general equilibrium securities model where assets pay in money the generic dimension of the set of equilibrium allocations in the incomplete market situation is s 1 where s is the number of assets hence the degree or real indeterminacy is independent of the number of assets this result requires beyond fewer assets than states that the number of traders be larger than the number of securities and that the asset return matrix be in general position the generic dimension for arbitrary returns matrix is also obtained it is argued in addition that the presence of real or mixed assets does not by itself lower the degree of indeterminacy

a space time random field model for electricity forward prices abstract stochastic models for forward electricity prices are of great relevance nowadays given the major structural changes in the market due to the increase of renewable energy in the production mix in this study we derive a spatio temporal dynamical model based on the heath jarrow morton hjm approach under the musiela parametrization which ensures an arbitrage free model for electricity forward prices the model is fitted to a unique data set of historical price forward curves as a particular feature of the model we disentangle the temporal from spatial maturity effects on the dynamics of forward prices and shed light on the statistical properties of risk premia of the noise volatility term structure and of the spatio temporal noise correlation structures we find that the short term risk premia oscillates around zero but becomes negative in the long run we identify the samuelson effect in the volatility term structure and volatility bumps explained by market fundamentals furthermore we find evidence for coloured noise and correlated residuals which we model by a hilbert space valued normal inverse gaussian levy process with a suitable covariance functional

financial markets and the political structure of the enterprise abstract this paper argues that competitive financial markets disfavor democratic enterprises even assuming such enterprises suffer no allocational deficiencies this conclusion follows from five assertions a the democratic enterprise requires access to credit markets b access to credit presupposes access to equity markets c the democratic firm s optimal risk level is lower than that desired by stockholders d the risk level assumed by the firm is costly to observe subject to inaccurate measurement and contractually unenforceable and e the incentives required to induce stockholder favorable risk behavior are more costly for democratic firms than for firms with stockholder accountable management

the taxation of trades in assets when the asset market is incomplete there typically exist taxes on trades in assets that are pareto improving this fiscal policy is anonymous it is fully and correctly anticipated by traders and it results in ex post pareto optimal allocations as such it improves over previously proposed constrained interventions

peer monitoring and credit markets a major problem for institutional lenders is ensuring that borrowers exercise prudence in the use of the funds so that the likelihood of repayment is enhanced one partial solution is peer monitoring having neighbors who are in a good position to monitor the borrower be required to pay a penalty if the borrower goes bankrupt peer monitoring is largely responsible for the successful financial performance of the grameen bank of bangladesh and of similar group lending programs elsewhere but peer monitoring has a cost it transfers risk from the bank which is in a better position to bear risk to the cosigner in a simple model of peer monitoring in a competitive credit market this article demonstrates that the transfer of risk leads to an improvement in borrowers welfare

deficient foresight a troublesome theme in keynesian economics the fact that john maynard keynes had made a distinguished contribution to the theory of probability 1921 no doubt predisposed many of his readers to imbue with great significance his subsequent remarks on the related topic of uncertainty in economic decision making among those who have provided commentaries on his work there are those who have singled out this uncertainty theme not only for its special importance but also for its potential for analytical subversion the purpose of this paper is to scrutinize the ideas involved in this particular aspect of keynes work together with the lines of argument that have emerged from those commentators who have pursued it the result of this scrutiny will be to call into question the idea that there is anything peculiarly subversive in the analytical consequences of broaching problems of uncertainty in economic decision making i shall argue rather that as an analytical issue it is depending on how it is handled either innocuous or else quite indiscriminately destructive

diversification as a public good community effects in portfolio choice within a rational general equilibrium model in which agents care only about personal consumption we consider a setting in which due to borrowing constraints individuals endowed with local resources underparticipate in financial markets as a result investors compete for local resources through their portfolio choices even with complete financial markets and no aggregate risk agents may herd into risky portfolios this yields a pareto dominated outcome as agents introduce community risk unrelated to fundamentals moreover if some agents are behaviorally biased or cannot completely diversify their holdings rational agents may choose more extreme portfolios and amplify the effect

corporate takeovers the efficiency arguments in recent years the tender offer takeover has been praised and damned with a ferocity suggesting that the survival of capitalism is at stake the truth as in most disputes with substantial metaphysical content is more prosaic some takeovers enhance economic efficiency some degrade it and the balance of effects though not fully known is most likely a close one in this essay i try to lay bare the debate s foundations and bring it back to earth with an injection of evidence

efficiency and equilibrium when preferences are time inconsistent abstract we consider an exchange economy with time inconsistent consumers whose preferences are additively separable if consumers have identical discount factors then allocations that are pareto efficient at the initial date are also renegotiation proof in an economy with a sequence of markets competitive equilibria are pareto efficient in this sense and for generic endowments only if preferences are locally homothetic

the inefficiency of the stock market equilibrium this paper establishes that when there is not a complete set of markets but more than one commodity the stock market equilibrium will not in general be a constrained pareto optimum the economy will lack both the property of exchange and production efficiency necessary conditions which must be satisfied if the economy is to be a constrained pareto optimum for all technologies are derived if all individuals have identical homothetic indifference maps then either there must be unitary price elasticities so there is no effective risk or all individuals must have the same degree of risk aversion so there is no trade on the stock market

recursive equilibrium in stochastic overlapping generations economies we prove the generic existence of a recursive equilibrium for overlapping generations economies with uncertainty generic here means in a residual set of utilities and endowments the result holds provided there is a sufficient number of potentially different individuals within each cohort

banks and markets in a monetary economy abstract modern financial sectors consist of banks asset markets and a central bank this paper builds a model where these institutions provide different financial services and their interaction supports efficient allocations when one institution is missing equilibria are by construction inefficient the paper analyzes how interest rates and asset prices depend on the structure of the financial sector and characterizes the central bank policy that supports efficient allocations the analysis relies on the difference between liquidity and real shocks and relates the notion of liquidity used in this paper to the one adopted in other studies

short memory equilibrium in stochastic overlapping generations economies abstract in stochastic olg exchange economies we show that short memory equilibria the natural extension from deterministic economies of steady states low order cycles or finite state space stationary sunspots equilibria fail to exist generically in utilities as a result even with independent and identically distributed exogenous shocks there is serial correlation in endogenous economic variables in equilibrium this arises even if utilities are time separable some goods inferior and there are no technological lags hence the origins of economic fluctuations can be traced only to the demographic structure of a heterogeneous agent multiple good economy

rational expectations in the overlapping generations model abstract this paper reports results on the character of the rational expectations equilibria of a stochastic overlapping generations model with heterogenous markets the model considered is a stationary overlapping generations model in which the endowments of young agents are subject to i i d random shocks the main result shown is that if there are l 1 commodities traded in every period then for most preferences the rational expectations equilibrium stochastic process of prices and allocations necessarily exhibits serial correlation this is in marked contrast to the one commodity model in which there always exists an equilibrium which is measure isomorphic to the endowment process

symposium on organizations and economics m t r ost production in modern economies occurs within organizations and this production is regulated only to a limited extent by prices the size of some of the largest organizations like general motors or ibm or att if managers didn t they would be replaced and firms that didn t maximize value wouldn t survive accordingly what went on inside the black box was mere detail the behavior of the firm could be described completely without knowledge of those details

stationary equilibria with incomplete markets and overlapping generations recent work on general equilibrium models with incomplete financial markets has demonstrated that when assets pay off in units of account equilibrium prices and allocations are indeterminate the equilibria in such models are also generically constrained suboptimal a central planner can typically reallocate assets in such a way as to pareto dominate the competitive equilibrium in this paper the authors consider an overlapping generations model with incomplete markets in which one asset is fiat money they show that when outside money has value in equilibrium the stationary equilibrium prices and allocations are both locally isolated and constrained optimal copyright 1992 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association