a theory of commerce abstract the theory of commerce advanced here captures prominent features of retail trade large employment congestion effects anonymous posted prices and quantity discounts this theory is built around a directed search model where buyers preferences are private information the analytical solution is easily inserted in a neoclassical growth framework in this framework the parameters of retail trade are calibrated using commercial margins and employment welfare properties depend on the sellers ability to charge two tier prices with two tier prices the directed search equilibrium is efficient otherwise it is not this contrasts with the full information benchmark where directed search is always efficient

contagion as a wealth effect financial contagion is described as a wealth effect in a continuous time model with two risky assets and three types of traders noise traders trade randomly in one market long term investors provide liquidity using a linear rule based on fundamentals convergence traders with logarithmic utility trade optimally in both markets asset price dynamics are endogenously determined numerically as functions of endogenous wealth and exogenous noise when convergence traders lose money they liquidate positions in both markets this creates contagion in that returns become more volatile and more correlated contagion reduces benefits from portfolio diversification and raises issues for risk management during the f inancial panic associated with the default of the russian government in august 1998 and the subsequent collapse of the hedge fund long term capital management numerous hedge funds banks and securities firms tried simultaneously to reduce exposures to a variety of financial instruments such as russian bonds brazilian stocks u s mortgages spreads between on therun and off the run government securities and spreads between swaps and u s treasuries although the fundamental values of these positions would appear to have little correlation during this financial crisis the asset prices in these markets exhibited the following common empirical pattern 1 financial intermediaries suffered losses as prices moved against their positions 2 market depth and liquidity decreased simultaneously in several markets 3 the volatility of prices increased simultaneously in several markets and

network models and financial stability abstract systemic risk is a key concern for central banks charged with safeguarding overall financial stability in this paper we investigate how systemic risk is affected by the structure of the financial system we construct banking systems that are composed of a number of banks that are connected by interbank linkages we then vary the key parameters that define the structure of the financial system including its level of capitalisation the degree to which banks are connected the size of interbank exposures and the degree of concentration of the system and analyse the influence of these parameters on the likelihood of knock on defaults first we find that the better capitalised banks are the more resilient is the banking system against contagious defaults and this effect is non linear second the effect of the degree of connectivity is non monotonic i e initially a small increase in connectivity increases the contagion effect but after a certain threshold value connectivity improves the ability of a banking system to absorb shocks third the size of interbank liabilities tends to increase the risk of knock on default even if banks hold capital against such exposures fourth more concentrated banking systems are shown to be prone to larger systemic risk all else equal in an extension to the main analysis we study how liquidity effects interact with banking structure to produce a greater chance of systemic breakdown we finally consider how the risk of contagion might depend on the degree of asymmetry tiering inherent in the structure of the banking system a number of our results have important implications for public policy which this paper also draws out

equilibrium incentive contracts and efficiency wages we analyze the optimal efficiency wage contract when output is contractible but firms neither observe the workers effort nor their match specific productivity firms offer wage contracts that optimally trade off effort and wage costs as a result employed workers enjoy rents which in turn creates unemployment nonetheless the incentive power of the equilibrium wage contract is constrained efficient in the absence of taxes and unemployment benefits we also show that more high powered incentive contracts tend to be associated with higher equilibrium unemployment rates jel e24 j30 j41

interbank market liquidity and central bank intervention we develop a simple model of the interbank market where banks trade a long term safe asset when there is a lack of opportunities for banks to hedge idiosyncratic and aggregate liquidity shocks the interbank market is characterized by excessive price volatility in such a situation a central bank can implement the constrained efficient allocation by using open market operations to fix the short term interest rate it can be constrained efficient for banks to hoard liquidity and stop trading with each other if there is sufficient uncertainty about aggregate liquidity demand compared to idiosyncratic liquidity demand

a theory of disagreement in repeated games with bargaining this paper proposes a new approach to equilibrium selection in repeated games with transfers supposing that in each period the players bargain over how to play although the bargaining phase is cheap talk following a generalized alternating offer protocol sharp predictions arise from three axioms two axioms allow the players to meaningfully discuss whether to deviate from their plan the third embodies a theory of disagreement that play under disagreement should not vary with the manner in which bargaining broke down equilibria that satisfy these axioms exist for all discount factors and are simple to construct all equilibria generate the same welfare optimal play under agreement generally requires suboptimal play under disagreement whether patient players attain efficiency depends on both the stage game and the bargaining protocol the theory extends naturally to games with imperfect public monitoring and heterogeneous discount factors and yields new insights into classic relational contracting questions

sulfur dioxide control by electric utilities what are the gains from trade title iv of the 1990 clean air act amendments caaa established a market for transferable sulfur dioxide so2 emission allowances among electric utilities this market offers firms facing high marginal abatement costs the opportunity to purchase the right to emit so2 from firms with lower costs and this is expected to yield cost savings compared to a command and control approach to environmental regulation this paper uses econometrically estimated marginal abatement cost functions for power plants affected by title iv of the caaa to evaluate the performance of the so2 allowance market specifically we investigate whether the much heralded fall in the cost of abating so2 compared to original estimates can be attributed to allowance trading we demonstrate that for plants that use low sulfur coal to reduce so2 emissions technical change and the fall in prices of low sulfur coal have lowered marginal abatement cost curves by over 50 percent since 1985 the flexibility to take advantage of these chan

bank risk within and across equilibria abstract the global financial crisis highlighted that the financial system can be most vulnerable when it seems most stable this paper models non linear dynamics in banking small shocks can lead from an equilibrium with few bank defaults straight to a full freeze the mechanism is based on amplification between adverse selection on banks funding market and moral hazard in bank monitoring our results imply trade offs between regulators microprudential desire to shield individual weak banks and the macroprudential consequences of doing so moreover limiting bank reliance on wholesale funding always reduces systemic risk but limiting the correlation between bank portfolios does not

financial contagion through capital connections a model of the origin and spread of bank panics financial contagion is modeled as an equilibrium phenomenon in a dynamic setting with incomplete information and multiple banks the equilibrium probability of bank failure is uniquely determined we explore how the cross holding of deposits motivated by imperfectly correlated regional liquidity shocks can lead to contagious eects conditional on the failure of a financial institution we show that contagion is possible in the unique equilibrium of the economy and characterize exactly when it may exist at the same time we identify a direction of flow for contagious eects which provides a rationale for localized financial panics simulations identify the optimal level of interbank deposit holdings in the presence of contagion risk our results suggest that when the probability of bank failure is low maximal levels of interbank holdings are optimal when cross holding of deposits is complete we demonstrate that the intensity of contagion is increasing in the size of regionally aggregate liquidity shocks

dynamic interbank network analysis using latent space models longitudinal network data are increasingly available allowing researchers to model how networks evolve over time and to make inference on their dependence structure in this paper a dynamic latent space approach is used to model directed networks of monthly interbank exposures in this model each node has an unobserved temporal trajectory in a low dimensional euclidean space model parameters and latent banks positions are estimated within a bayesian framework we apply this methodology to analyze two different datasets the unsecured and the secured repo interbank lending networks we show that the model that incorporates a latent space performs much better than the model in which the probability of a tie depends only on observed characteristics the latent space model is able to capture some features of the dyadic data such as transitivity that the model without a latent space is not able to

efficiency wages and the business cycle puzzle abstract the main thrust of this work is to open the real business cycle rbc methodology to non walrasian considerations and reciprocally to submit some non walrasian models to the discipline of the rbc approach in doing so we provide a first rbc model with involuntary unemployment and a suboptimal equilibrium path we also demonstrate the promise and difficulty of resolving the business cycle puzzle by appealing to quantity rationing in the labor market

collusion and the banking structure of a duopoly the author shows that in credit relationships the choice of a lender may become a determinant of the extent of competition in downstream industries in the presence of imperfect output markets and asymmetric information in financial markets members of an industry may achieve a partial collusion in the output market by borrowing from the same bank in an oligopoly debt is procompetitive as it gives incentives to the borrowing firm to undertake an aggressive output strategy as both firms borrow the industry becomes more competitive and riskier the firms debt value is decreased a common lender can better control these incentive effects and hence limit the extent of competition in the output market

competitive search equilibrium in this paper i construct an equilibrium for markets with frictions which is competitive in the sense that all agents are price takers and maximize utility subject to a set of market parameters i show that the equilibrium allocation is socially optimal i also show how the competitive search equilibrium can be achieved if employers with vacancies can advertise publicly the wages they pay

dynamic contracts with worker mobility via directed on the job search this article proposes a model with dynamic incentive contracts and on the job search in a frictional labor market the optimal long term contract exhibits an increasing wage tenure profile with increasing wages worker effort also increases with tenure these two features imply that the probabilities of both voluntary and involuntary job separation decrease with both job tenure and the duration of employment given these results workers experience differing labor market transitions between employment unemployment and across different employers and the equilibrium generates endogenous heterogeneity among ex ante homogeneous workers abstract from author

contagion of self fulfilling financial crises due to diversification of investment portfolios abstract we look at two countries that have independent fundamentals but share the same group of investors each country might face a self fulfilling crisis agents withdrawing their investments fearing that others will a crisis in one country reduces agents wealth this makes them more averse to the strategic risk associated with the unknown behavior of other agents in the second country increasing their incentive to withdraw their investments consequently the probability of a crisis there increases this generates a positive correlation between the returns in the two countries since diversification affects returns in our model its welfare implications are non trivial

the effects of interbank networks on efficiency and stability in a macroeconomic agent based model we develop a macroeconomic agent based model that consists of firms banks unions and households who interact on labour goods credit and interbank markets the model endogenises pricing decisions by firms wage setting by unions and interest rate setting by banks on both firm and interbank lending banks also set leverage targets and precautionary liquidity buffers on the basis of internal risk models our model produces endogenous fluctuations driven by the pricing behaviour of firms and the wage setting behaviour of unions fluctuations lead to loan defaults which are exacerbated as lenders reduce lending and charge higher interest rates inducing a credit crunch we also study how making the inter banking network more connected affects the key outcomes of the economy and find that while the flow of funds from surplus banks to firms can be increased the latter effect is soon dominated by increasing instability in the real sector as firms default at higher rates while the banking sector experiences fewer defaults as a whole losses on the interbank market increase as a source of bank defaults

contagion and risk sharing on the inter bank market abstract increasing inter bank lending has an ambiguous impact on financial stability using a computational model with endogenous bank behavior and interest rates we identify the conditions under which inter bank lending promotes stability through risk sharing or provides a channel through which failures may spread in response to large economy wide shocks more inter bank lending relationships worsen systemic events for smaller shocks the opposite effect is observed as such no inter bank market structure maximizes stability under all conditions in contrast deposit insurance costs are always reduced under greater numbers of inter bank lending relationships a range of regulations are considered to increase system stability

learning by doing vs learning about match quality can we tell them apart understanding the accumulation of match specific capital is crucial in shedding light on the reasons for the prevalence of long term employ ment relationships and on the welfare consequences of turnover in the labor market one of the most important source of match specific capital is human capital acquired through match specific learning such learn ing can take on two distinct forms in the first case workers accumulate match specific human capital through learning by doing in the second case a worker and a firm in an employment relationship learn about the quality of the match over time thereby acquiring valuable information i construct a structural model that embeds these two learning explana tions i show that it is possible to distinguish the two explanations given turnover data on employing firms coupled with data on workers such data now exist in the form of matched employer employee data sets i use a matched french data set to estimate the structural model using the efficient method of moments a simulation based estimation method i find that while learning by doing could be present in the first few months of an employment relationship learning about match quality dominates at tenures above half a year this finding has important consequences for economists understanding of the sources of match specific capital and for the desirability of policies that alter the incentives for turnover for workers of different tenure

prices debt and market structure in an agent based model of the financial market we develop an agent based model in which heterogeneous and boundedly rational agents interact by trading a risky asset at an endogenously set price agents are endowed with balance sheets comprising the risky asset as well as cash on the asset side and equity capital as well as debt on the liabilities side a number of findings emerge when simulating the model we find that the empirically observable log normal distribution of bank balance sheet size naturally emerges and that higher levels of leverage lead to a greater inequality among agents furthermore greater leverage increases the frequency of bankruptcies and systemic events credit frictions which we define as the stickiness of debt adjustments are able to explain a key difference in the relation between leverage and assets observed for different bank types lowering credit frictions leads to an increasingly procyclical behavior of leverage which is typical for investment banks nevertheless the impact of credit frictions on the fragility of the model financial system is complex lower frictions do increase the stability of the system most of the time while systemic events become more probable in particular we observe an increasing frequency of severe liquidity crises that can lead to the collapse of the entire model financial system

on the job search and moral hazard we analyze the interaction between intertemporal incentive contracts and search frictions associated with on the job search in our model agency problems call for wage contracts with deferred compensation at the same time workers do on the job search deferred compensation improves workers incentives to exert effort but distorts their on the job search decisions we show that deferred compensation is less attractive when the value to the worker firm pair of on the job search is high moreover the interplay between search frictions and wage contracts creates feedback effects if firms in equilibrium use contracts with deferred compensation fewer firms with vacancies enter the on the job search market and this in turn reduces the distortions created by deferred compensation these feedback effects between the incentive contracts used and the activity level in the search markets can lead to multiple equilibria a low turnover equilibrium where firms use deferred compensation and a high turnover equilibrium where they do not furthermore the model predicts that firms are more likely to use deferred compensation when search frictions are high and when the gains from on the job search are small

performance pay and adverse selection it is well known in personnel economics that firms may improve the quality of their workforce by offering performance pay we analyze an equilibrium model where worker productivity is private information and show that the firms gain from worker self selection may not be matched by a corresponding social gain in particular the equilibrium incentive contracts are excessively high powered thereby inducing the more productive workers to exert too much effort and increasing agency costs stemming from the misallocation of effort

estimating bilateral exposures in the german interbank market is there a danger of contagion abstract credit risk associated with interbank lending may lead to domino effects where the failure of one bank results in the failure of other banks not directly affected by the initial shock recent work in economic theory shows that this risk of contagion depends on the precise pattern of interbank linkages we use balance sheet information to estimate a matrix of bilateral credit relationships for the german banking system and test whether the breakdown of a single bank can lead to contagion we find that in the absence of a safety net there is considerable scope for contagion that could affect a large proportion of the banking system the financial safety net in this case institutional guarantees for saving banks and cooperative banks considerably reduces but does not eliminate the danger of contagion even so the failure of a single bank could lead to the breakdown of up to 15 of the banking system in terms of assets

a model of a systemic bank run abstract this paper provides a model of the view that the 2008 financial crisis is reminiscent of a bank run focussing on six stylized key features in particular core financial institutions have invested their funds in asset backed securities rather than committed to long term projects in distress these can potentially be sold to a large pool of outside investors at steep discounts i consider two different motives for outside investors and their interaction with banks trading asset backed securities uncertainty aversion versus adverse selection i shall argue that the version with uncertainty averse investors is more consistent with the stylized facts than the adverse selection perspective in the former the crisis deepens the larger the market share of distressed core banks while a run becomes less likely instead as a result in the adverse selection version therefore the outright purchase of troubled assets by the government at prices above current market prices may both alleviate the financial crises as well as provide tax payers with returns above those for safe securities

private information wage bargaining and employment fluctuations shimer 2005 pointed out that although we have a satisfactory theory of why some workers are unemployed at any given time we don t know why the number of unemployed workers varies so much over time the basic mortensen pissarides 1994 model does not generate nearly enough volatility in unemployment for plausible parameter values this paper extends the mortensen pissarides model to allow for informational rents productivity is subject to publicly observed aggregate shocks and to idiosyncratic shocks that are seen only by the employer it is shown that there is a unique equilibrium provided that the idiosyncratic shocks are not too large the main result is that small fluctuations in productivity that are privately observed by employers can give rise to a kind of wage stickiness in equilibrium and the informational rents associated with this stickiness are sufficient to generate relatively large unemployment fluctuations

labor turnover and the natural rate of unemployment efficiency wage vs frictional unemployment wage and unemployment responses to changes in economic environment are compared for efficiency wage and frictional models changes in aggregate demand persistence of job specific shocks cost of living and unemployment benefits are considered wages and unemployment move in the same direction in the two models except that an upward shift in aggregate labor demand can reduce the real wage in the efficiency wage but not the frictional model in a numerical simulation calibrated to u s data real productivity shocks in the efficiency wage model yield a ratio of unemployment to wage variability close to that of the united states

micro level transmission of monetary policy shocks the trading book channel abstract we open the black box of the monetary policy transmission mechanism with a granular model that considers the balance sheet composition and network relationships of each economic agent though there are several well documented channels through which monetary policy operates we focus on the overlooked trading book channel which arises because of adjustments in the accounting value of trading book exposures on banks balance sheets that have to be marked to market when interest rates change variations in banks net worth due these adjustments are used as input to a network model that incorporates the financial and corporate sectors the framework permits us to determine the effects of interest rate changes on every bank and firm in the economy and any second round contagion effects in the short run we apply the model to a comprehensive database of brazilian banks and firms from 2015 to 2020 we find that interest rate shocks affect more strongly financial stability in periods of monetary policy tightening we also find notable asymmetric effects of positive and negative interest rate shocks in the brazilian economy with positive interest rate shocks affecting more financial stability finally our results also suggest a non linear relationship between interest rate changes and financial stability reinforcing the need to mitigate monetary policy shocks through interest rate smoothing and adequate communication and transparency to society

capital structure and interaction among firms in output markets theory and evidence i develop a simple model that examines the relations between the extent of competitive interaction among firms in output markets their capital structures and the aggressiveness of their operating strategies a firm s optimal leverage is related to the degree to which its operating strategy affects its rivals value functions and resulting optimal output market choices this relation is positive regardless of whether the competition in output markets is in strategic substitutes or in strategic complements i test the model s prediction using two proxies for the extent of competitive interaction among firms the empirical evidence provides support for the model

debt and the marginal tax rate abstract do taxes affect corporate debt policy this paper tests whether the incremental use of debt is positively related to simulated firm specific marginal tax rates that account for net operating losses investment tax credits and the alternative minimum tax the simulated marginal tax rates exhibit substantial variation due to the dynamics of the tax code tax regime shifts business cycle effects and the progressive nature of the statutory tax schedule using annual data from more than 10 000 firms for the years 1980 1992 i provide evidence which indicates that high tax rate firms issue more debt than their low tax rate counterparts

a network analysis of the italian overnight money market the objective of this paper is to analyse the network topology of the italian segment of the european overnight money market through methods of statistical mechanics applied to complex networks we investigate differences in the activities of banks of different sizes and the evolution of their connectivity structure over the maintenance period the main purpose of the analysis is to establish the potential implications of the current institutional arrangements on the stability of the banking system and to assess the efficiency of the interbank market in terms of absence of speculative and preferential trading relationships

on the existence of an optimal capital structure theory and evidence one of the most contentious issues in the theory of finance during the past quarter century has been the theory of capital structure the geneses of this controversy were the seminal contributions by modigliani and miller 18 19 the general academic view by the mid 1970s although not a consensus was that the optimal capital structure involves balancing the tax advantage of debt against the present value of bankruptcy costs no sooner did this general view become prevalent in the profession than miller 16 presented a new challenge by showing that under certain conditions the tax advantage of debt financing at the firm level is exactly offset by the tax disadvantage of debt at the personal level since then there has developed a burgeoning theoretical literature attempting to reconcile miller s model with the balancing theory of optimal capital structure e g deangelo and masulis 5 kim 12 and modigliani 17 the general result of this work is that if there are significant leverage related costs such as bankruptcy costs agency costs of debt and loss of non debt tax shields and if the income from equity is untaxed then the marginal bondholder s tax rate will be less than the corporate rate and there will be a positive net tax advantage to corporate debt financing the firm s optimal capital structure will involve the trade off between the tax advantage of debt and various leverage related costs the upshot of these extensions of miller s model is the recognition that the existence of an optimal capital structure is essentially an empirical issue as to whether or not the various leverage related costs are economically significant enough to influence the costs of corporate borrowing the miller model and its theoretical extensions have inspired several timeseries studies which provide evidence on the existence of leverage related costs trczinka 28 reports that from examining differences in average yields between taxable corporate bonds and tax exempt municipal bonds one cannot reject the miller hypothesis that the marginal bondholder s tax rate is not different from the corporate tax rate however trczinka is careful to point out that this finding does not necessarily imply that there is no tax advantage of corporate debt if the personal tax rate on equity is positive indeed buser and hess 1 using a longer time series of data and more sophisticated econometric techniques estimate that the average effective personal tax rate on equity is statistically positive and is not of a trivial magnitude more importantly they document evidence that is consistent with the existence of significant leverage related costs in the economy

on the debt capacity of growth options we relate the value of growth options in the firm s investment opportunity set to the level of debt in the firm s capital structure underinestment costs of debt increase and free cash flow benefits fall with additional growth options thus if debt capacity is defined as the amount of debt the firm optimally adds for an incremental project then the debt capacity of growth options is negative this result implies that book leverage should fall with the addition of growth options our tests using a large sample of industrial firms confirm this prediction

overlapping portfolios contagion and financial stability abstract we study the problem of interacting channels of contagion in financial networks the first channel of contagion is counterparty failure risk this is captured empirically using data for the austrian interbank network the second channel of contagion is overlapping portfolio exposures this is studied using a stylized model we perform stress tests according to different protocols for the parameters we study neither channel of contagion results in large effects on its own in contrast when both channels are active at once bankruptcies are much more common and have large systemic effects

banking panics the role of the first come first served rule and information externalities this paper proposes that both the first come first served rule and information externalities are important in causing contagious bank runs the first come first served rule creates a negative payoff externality among depositors this payoff externality forces depositors to respond to early noisy information such as failures of other banks therefore failures of a few banks may trigger runs on other banks contagious runs may occur even if i depositors choose the pareto dominant equilibrium when there are multiple equilibria and ii the deposit contract is chosen to maximize depositor welfare the feasibility of reforming the fdic to impose market discipline is also investigated

a model of financial fragility abstract this article presents a dynamic stochastic game theoretic model with two essential features first agents hold diversified portfolios that link their financial positions to those of other agents second shocks to fundamentals at the initial date cause some portfolio losses agents who incur losses reallocate their portfolios thereby breaking some linkages in the pareto efficient symmetric equilibrium studied two related types of financial crisis can occur in response one occurs gradually as losses spread breaking more links the other type occurs instantaneously when forward looking agents preemptively shift to safer portfolios to avoid future losses from contagion an economy is more fragile the earlier its last remaining link breaks from such a crisis journal of economic literature classification numbers c7 e00 e3 e44 g1

crisis and responses the federal reserve in the early stages of the financial crisis in summer 2007 u s and global financial markets found themselves facing a potential financial crisis and the u s federal reserve found itself in a difficult situation it was becoming clear that banks and other financial institutions would ultimately lose tens or even hundreds of billions of dollars from their exposure to subprime mortgage market loans bank lending is closely tied to bank capital or net worth specifically bank regulators require that loans not exceed a certain multiple of capital thus the federal reserve faced the danger of a sharp contraction in credit and bank lending in a way that threatened a deep recession or worse when this kind of event happens the job of the central bank is to assure that financial institutions have the necessary funds to conduct their daily business that they have the liquidity they need to make timely payments and transfers modern financial institutions need to replenish their funding every day in the united states alone literally trillions of dollars are transferred between banks each day to support the 50 trillion credit outstanding in the economy as a whole commercial banks require funds to initiate the mortgages auto loans and credit card debt they then sell into financial markets while investment banks finance much of their activity with daily borrowing in the early stages of the crisis the situation often arose in which a wellcapitalized bank was forced to make sudden large loans based on previously committed lines of credit in this circumstance central bank actions can ease

debt agency costs and industry equilibrium we show that risk characteristics of projects cash flows are endogenously determined by the investment decisions of all firms in an industry as a result in reasonable settings financial structures which create incentives to expropriate debtholders by increasing risk are shown not to reduce value in an industry equilibrium without taxes capital structure is irrelevant for individual firms despite its effect on the equityholders incentives but the maximum total amount of debt in the industry is determinate allowing for a corporate tax advantage of debt capital structure becomes relevant but firms are indifferent between distinct alternative debt levels the effect of firms financial structures on subsequent investment and output decisions has recently received considerable attention in the finance literature the central insight that equityholders control the firm s investment and production decisions and in general do not maximize the value of a levered firm has been applied to the analysis of risk shifting underinvestment and firms abilities to enter into optimal contracts with their customers existing models of firms financial structures and their effect on investment decisions are generally based on a single firm framework and do not take into account the relationship between project cash flows and the investment decisions of all firms in the industry 2 in this paper we allow the distribution of investment projects within an industry to adjust and show that this generates new insights and reverses several key results of single firm agency cost models the new predictions conform with well documented

stability analysis of financial contagion due to overlapping portfolios abstract common asset holdings are widely believed to have been the primary vector of contagion in the recent financial crisis we develop a network approach to the amplification of financial contagion due to the combination of overlapping portfolios and leverage and we show how it can be understood in terms of a generalized branching process this can be used to compute the stability for any particular configuration of portfolios by studying a stylized model we estimate the circumstances under which systemic instabilities are likely to occur as a function of parameters such as leverage market crowding diversification and market impact although diversification may be good for individual institutions it can create dangerous systemic effects and as a result financial contagion gets worse with too much diversification there is a critical threshold for leverage below it financial networks are always stable and above it the unstable region grows as leverage increases note that our model assumes passive portfolio management during a crisis however we show that dynamic deleveraging during a crisis can amplify instabilities the financial system exhibits robust yet fragile behavior with regions of the parameter space where contagion is rare but catastrophic whenever it occurs our model and methods of analysis can be calibrated to real data and provide simple yet powerful tools for macroprudential stress testing

the role of demandable debt in structuring optimal banking arrangements demandable debt finance by banks warrants explanation because it entails costs of bank suspension liquidation and idle reserve holdings an explanation is developed in which demandable debt provides incentive compatible intermediation where the banker has comparative advantage in allocating investment funds but may act against the interests of uninformed depositors demandable debt attracts funds by giving depositors an option to force liquidation its usefulness in transacting follows from information sharing between monitors and nonmonitors copyright 1991 by american economic association

the effect of the interbank network structure on contagion and common shocks abstract this paper proposes a dynamic multi agent model of a banking system with central bank banks optimize a portfolio of risky investments and riskless excess reserves according to their risk return and liquidity preferences they are linked via interbank loans and face stochastic deposit supply comparing different interbank network structures it is shown that money centre networks are more stable than random networks evidence is provided that the central bank stabilizes interbank markets in the short run only systemic risk via contagion is compared with common shocks and it is shown that both forms of systemic risk require different optimal policy responses

embodied technical change and the fluctuations of unemployment and wages a matching model where technological change is partially embodied in the job match is shown to be successful in explaining the variability of unemployment and vacancies if we incorporate long term wage contracts into the model it also explains a number of stylized facts on the dynamics of real wages which have been found in the empirical labor literature

liaisons dangereuses increasing connectivity risk sharing and systemic risk the recent financial crisis poses the challenge to understand how systemic risk arises endogenously and what architecture can make the financial system more resilient to global crises this paper shows that a financial network can be most resilient for intermediate levels of risk diversification and not when this is maximal as generally thought so far this finding holds in the presence of the financial accelerator i e when negative variations in the financial robustness of an agent tend to persist in time because they have adverse effects on the agent s subsequent performance through the reaction of the agent s counterparties 2012 elsevier b v all rights reserved

incentives in competitive search equilibrium this paper proposes a labor market model with job search frictions where workers have private information on match quality and eort firms use wage contracts to motivate workers in addition wages are also used to attract employees we de ne and characterize competitive search equilibrium in this context and show that it satis es a simple modi ed hosios rule the model is used to address the shimer puzzle related to the low volatility of the unemployment rate relative to the volatility of output observed in the data we nd that private information may increase the responsiveness of the unemployment rate to changes in productivity and in particular to changes in

equilibrium matching and termination in an equilibrium model of the labor market with moral hazard jobs are dynamic contracts job separations are terminations of optimal dynamic contracts transitions from unemployment to new jobs are modeled as a process of random matching and nash bargaining non employed workers make consumption and saving decisions as in a standard growth model as well as whether or not to participate in the labor market the stationary equilibrium is characterized the model is then calibrated to the u s labor market to study quantitatively the worker flows and distributions the compensation dynamics and the effects of ui system

competitive equilibrium with search frictions a general equilibrium approach abstract when the trading process is characterized by search frictions traders may be rationed so markets need not clear we build a general equilibrium model with transferable utility where the uncertainty arising from rationing is incorporated in the definition of a commodity in the spirit of the arrow debreu theory prices of commodities then depend not only on their physical characteristics but also on the probability that their trade is rationed the standard definition of competitive equilibrium is extended by replacing the market clearing condition with an exogenous matching function which describes a trading technology that is not frictionless as is typical in search models the matching function relates the rationing probabilities of buyers and sellers to the ratio of buyers to sellers in the market when search frictions vanish our model is equivalent to the continuous assignment model of gretsky et al 20 we adapt their approach which uses linear programming techniques and duality theory to show that a competitive equilibrium exists and is constrained efficient in our environment our competitive equilibrium notion is equivalent to that of directed or competitive search the strength of our formulation and the linear programming approach is that they allow us to generalize the constrained efficiency and existence results in the directed search literature to a much broader class of economies our framework also opens the door to the use of existing algorithms for computing equilibria and taking these models to the data

competitive screening under heterogeneous information we study the interplay between informational frictions and second degree price discrimination our theory recognizes that consumers differ in their tastes for quality as well as in the information they possess about available offers which leads to dispersion over price quality menus in equilibrium while firms are ex ante identical we show that their menus are ordered so that more generous menus leave more surplus to consumers of all valuations we explore the cross section of equilibrium menus and variations in market conditions to generate empirical predictions on prices qualities and markups across firms and within a firm s product line for instance more competition may raise prices for low quality goods yet consumers are better off as the qualities they receive also increase the predictions of our model illuminate empirical findings in many markets such as those for cell phone plans yellow pages advertising cable tv and air travel

financial regulations and bank credit to the real economy we present a new agent based model focusing on the linkage between the interbank market and the real economy with a stylised central bank acting as lender of last resort using this model we address the tradeoff between stability and economic performance for different structures of the interbank market we also explore the efficacy of recent regulatory reforms using our richer model our results suggest that the effects of regulatory leverage ratios on the banking sector s performance can vary in a complex and non monotonic way with the state of the economy the degree of connectivity of the interbank market and the amount of information available to market participants on bank risks

competitive pricing and efficiency in search equilibrium we consolidate and generalize some results on price determination and efficiency in search equilibrium extending models by rubinstein and wolinsky and by gale heterogeneous buyers and sellers meet according to a general matching technology and prices are determined by a general bargaining condition when the discount rate r and search costs converge to 0 we show that prices in all exchanges are the same and equal the competitive market clearing price given positive search costs efficiency obtains iff bargaining satisfies hosios condition and r 0 when prices are set by third party market makers however we show that search equilibrium is necessarily efficient

holdups and efficiency with search frictions a natural holdup problem arises in a market with search frictions firms have to make a range of investments before finding their employees and larger investments translate into higher wages in particular when wages are determined by ex post bargaining the equilibrium is always inefficient recognizing that capital intensive production relations have to pay higher wages firms reduce their investments this can only be prevented by removing all the bargaining power from the workers but this in turn depresses wages below their social product and creates excessive entry of firms in contrast to this benchmark we show that efficiency is achieved when firms post wages and workers can direct their search toward more attractive offers this efficiency result generalizes to an environment with imperfect information where workers only observe a few of the equilibrium wage offers we show that the underlying reason for efficiency is not wage posting per se but the ability of workers to direct their search toward more capital intensive jobs

heterogeneity job creation and unemployment volatility in this paper i explore the impact of match specific heterogeneity at the job creation margin on business cycle fluctuations i show that this form of heterogeneity alone does not help to amplify labor market volatility either under full or under asymmetric information first i show analytically that under full information heterogeneity has no first order effect on the response of unemployment and job creation to productivity and actually tends to dampen the response of market tightness then in a series of calibrations i show that with both full and asymmetric information the model delivers labor market volatilities close to the representative agent full information benchmark

business cycles with worker moral hazard we consider an economy with unemployment where firms pay efficiency wages due to effort enforcement problems and face output prices that vary cyclically between a high and a low level ph and pl we show that for a range of pl ph 1 employment and the wage will be cylically rigid and that this range is greater the shorter h periods are for lower pl ph employment will vary procyclically but then also the wage and more so the more employment varies this implies a limited role for efficiency wage theory in explaining employment variations over the business cycle but a greater role for explaining productivity fluctuations according to okun s law

interbank contagion an agent based model approach to endogenously formed networks abstract the potential impact of interconnected financial institutions on interbank financial systems is a financial stability concern for central banks and regulators in examining how financial shocks propagate through contagion effects we argue that endogenous individual bank choices are necessary to properly consider how losses develop as the interbank lending network evolves we present an agent based model to endogenously reconstruct interbank networks based on 6600 banks decision rules and behaviors reflected in quarterly balance sheets we compare the results of our model to the results of a traditional stationary network framework for contagion the model formulation reproduces dynamics similar to those of the 2007 09 financial crisis and shows how bank losses and failures arise from network contagion and lending market illiquidity when calibrated to post crisis data from 2011 to 2014 the model shows the u s banking system has reduced its likelihood of bank failures through network contagion and illiquidity given a similar stress scenario

macro networks an application to euro area financial accounts abstract this paper develops a financial network designated the macro network that depicts the connections between the main financial and non financial sectors of the economy in the various financial instruments of the euro area the macro network comprises of linkages across financial and non financial sectors in each country these country level sector networks are then connected by the cross border links between the individual banking sectors using the macro network to simulate financial shocks we find that the propagation effects depend on the underlying network structure which evolves over time after the financial crisis bilateral linkages contracted sharply reflecting the surge in counterparty risk and the de leveraging processes nonetheless our analysis suggests that even after this process vulnerabilities remained in the euro area financial system while a more diversified portfolio of cross border exposures might mitigate the shock effects we identify sectors which are most relevant for the propagation of financial shocks in the macro network

motivation and markets many workers receive pay based on subjectively assessed performance yet the shirking model of efficiency wages excludes it this paper incorporates such pay with the following results performance pay is more efficient than efficiency wages when the costs of having a job vacant are low and qualified workers in short supply more capital intensive industries pay more than less capital intensive industries as observed in studies of interindustry wages differentials sustaining an efficient outcome requires a social convention similar to the notion of a fair wage the model also makes predictions about the relationship between turnover wages growth and unemployment copyright 1998 by american economic association

applications and interviews firms recruiting decisions in a frictional labour market i develop a directed search model to study the recruitment decisions of firms competing for workers who ex post differ in two dimensions 1 their match productivity and 2 their probability of accepting a job offer endogenously determined by their choice of application portfolio to attract these workers firms post a recruiting intensity and a hiring standard in addition to terms of trade a higher recruiting intensity is costly but allows the firm to select more applicants for an interview which reveals their productivity the hiring standard solves the tradeoff between immediate hiring and waiting for a potentially better match in the future i characterize equilibrium and find that various outcomes including uniqueness of equilibrium and the cyclicality of recruiting intensity crucially depend on firms recruiting cost and workers search cost calibration of the model to the u s labour market indicates a continuum of equilibria given selection of a particular equilibrium hiring standards are countercyclical while recruiting intensity is procyclical the calibrated model creates more amplification than a standard model without intensive margins and gives rise to procyclical match efficiency when viewed through the lens of a cobb douglas matching function

systemic risk in financial systems we consider default by firms that are part of a single clearing mechanism the obligations of all firms within the system are determined simultaneously in a fashion consistent with the priority of debt claims and the limited liability of equity we first show via a fixed point argument that there always exists a clearing payment vector that clears the obligations of the members of the clearing system under mild regularity conditions this clearing vector is unique next we develop an algorithm that both clears the financial system in a computationally efficient fashion and provides information on the systemic risk faced by the individual system firms finally we produce qualitative comparative statics for financial systems these comparative statics imply that in contrast to single firm results even unsystematic nondissipative shocks to the system will lower the total value of the system and may lower the value of the equity of some of the individual system firms

efficient unemployment insurance this paper constructs a tractable general equilibrium model of search with risk aversion an increase in risk aversion reduces wages unemployment and investment unemployment insurance has the opposite effect insured workers seek high wage jobs with high unemployment risk an economy with risk neutral workers achieves maximal output without any unemployment insurance but an economy with risk averse workers requires a positive level of unemployment insurance to maximize output therefore moderate unemployment insurance not only improves risk sharing but also increases output

interbank lending and systemic risk systemic risk refers to the propagation of a bank s economic distress to other economic agents linked to that bank through financial transactions banking authorities often prevent systemic risk through an implicit insurance of interbank claims or by reducing interbank transactions and centralizing banks liquidity management this paper investigates whether the flexability afforded by decentralized bank interactions can be preserved while protecting the central banks from the necessity of conducting undesired rescue operations it develops a model in which decentralized interbank leading is motivated by peer monitoring in this context the paper derives the optimal prudential rules and in particular looks at the impact of interbank monitoring on the solvency and liquidity ratios of borrowing and lending banks last it provides conditions which a too big to fail policy is or is not justified and studies the possibility of propagation of a bank s liquidity shock throughout the financial system copyright 1996 by ohio state university press

heterogeneous beliefs in over the counter markets the behavior and stability of over the counter markets is of central concern to regulators little is known however about how the structure of these markets determine their properties in this paper we consider an over the counter market populated by boundedly rational heterogeneous traders in which the structure is represented by a network stability is found to decrease as the market becomes less well connected however the configuration of connections has a significant effect the presence of hubs such as those found in scale free networks increases stability and decreases volatility whilst small world short cut links have the opposite effect volatility in the fundamental value increases market volatility however volatility in the riskless asset returns has an ambiguous effect

the formation of a core periphery structure in heterogeneous financial networks recent empirical evidence suggests that nancial networks exhibit a core periphery network structure this paper aims at giving an economic explanation for the emergence of such a structure using network formation theory focusing on intermediation benets we nd that a core periphery network cannot be unilaterally stable when agents are homogeneous the best response dynamics converge to a unique unilaterally stable outcome ranging from an empty to denser networks as the costs of linking decrease a core periphery network structure can form endogenously however if we allow for heterogeneity among agents in size we show that our model can reproduce the observed core periphery structure in the dutch interbank market for reasonable parameter values

constrained efficiency with adverse selection and directed search abstract this paper studies constrained efficiency in guerrieri et al s 2010 model of adverse selection and directed search buyers post contracts and sellers with private information about their type direct their search toward their preferred contract buyers and sellers then match bilaterally and trade if the guerrieri shimer wright equilibrium fails to achieve the first best then the planner subject to the frictions of the environment achieves strictly higher welfare than the equilibrium i e the equilibrium is not ex ante constrained efficient under certain conditions the planner achieves an allocation that even pareto dominates the equilibrium i e the equilibrium is not interim constrained efficient under other conditions the planner can completely undo the effects of adverse selection and achieves the first best cross subsidization is the key to these results

networked relationships in the e mid interbank market a trading model with memory interbank markets are fundamental for bank liquidity management in this paper we introduce a model of interbank trading with memory our model reproduces features of preferential trading patterns in the e mid market recently empirically observed through the method of statistically validated networks the memory mechanism is used to introduce a proxy of trust in the model the key idea is that a lender having lent many times to a borrower in the past is more likely to lend to that borrower again in the future than to other borrowers with which the lender has never or has in frequently interacted the core of the model depends on only one parameter representing the initial attractiveness of all the banks as borrowers model outcomes and real data are compared through a variety of measures that describe the structure and properties of trading networks including number of statistically validated links bidirectional links and 3 motifs refinements of the pairing method are also proposed in order to capture finite memory and reciprocity in the model the model is implemented within the mason framework in java

interbank loans collateral and modern monetary policy this study develops a novel agent based model of the interbank market with endogenous credit risk formation mechanisms we allow banks to exchange funds through unsecured and secured transactions which facilitates the flow of funds to the most profitable investment projects risk premiums result from banks forecasting rules and depend on past performance of the benchmark risk factors and interest rates our model confirms basic stylized facts of the interbank interest rates and volumes we also find that network structures within the secured market segment are characterized by the presence of dealer banks while we do not observe similar patterns in the unsecured market we perturb the model with exogenous shocks and policy scenarios which correspond to unconventional monetary policies

how does industry affect firm financial structure we examine the importance of industry to firm level financial and real decisions we find that in addition to standard industry fixed effects financial structure also depends on a firm s position within its industry in competitive industries a firm s financial leverage depends on its natural hedge its proximity to the median industry capital labor ratio the actions of other firms in the industry and its status as entrant incumbent or exiting firm financial leverage is higher and less dispersed in concentrated industries where strategic debt interactions are also stronger but a firm s natural hedge is not significant our results show that financial structure technology and risk are jointly determined within industries these findings are consistent with recent industry equilibrium models of financial structure copyright 2005 oxford university press