the dynamics of the leverage cycle abstract we present a simple agent based model of a financial system composed of leveraged investors such as banks that invest in stocks and manage their risk using a value at risk constraint based on historical observations of asset prices the value at risk constraint implies that when perceived risk is low leverage is high and vice versa a phenomenon that has been dubbed pro cyclical leverage we show that this leads to endogenous irregular oscillations in which gradual increases in stock prices and leverage are followed by drastic market collapses i e a leverage cycle this phenomenon is studied using simplified models that give a deeper understanding of the dynamics and the nature of the feedback loops and instabilities underlying the leverage cycle we introduce a flexible leverage regulation policy in which it is possible to continuously tune from pro cyclical to countercyclical leverage when the policy is sufficiently countercyclical and bank risk is sufficiently low the endogenous oscillation disappears and prices go to a fixed point while there is always a leverage ceiling above which the dynamics are unstable countercyclical leverage policies can be used to raise the ceiling we also study the impact on leverage cycles of direct temporal control of the bank s riskiness via the bank s required value at risk quantile under such a rule the regulator relaxes the value at risk quantile following a negative stock price shock and tightens it following a positive shock while such a policy rule can reduce the amplitude of leverage cycles its effectiveness is highly dependent on the choice of parameters finally we investigate fixed limits on leverage and show how they can control the leverage cycle

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

dynamic programming model estimates of social security disability insurance application timing this paper develops a dynamic programming model of the social security disability insurance ssdi application timing decision we estimate the time to application from the point at which a health condition first begins to affect the kind or amount of work that a currently employed person can do we use health and retirement study hrs and restricted access social security earnings data for estimation our results show that the type of work limiting health condition presence of employer accommodation and the relative value of income in the application state to income in the work state significantly affect the timing of ssdi application copyright 2004 john wiley sons ltd

choice under uncertainty a model of applications for the social security disability insurance program abstract not all people with health problems are disabled some individuals with severe physical or mental impairments such as blindness or limb amputation continue to hold jobs and generally function satisfactorily they constitute however a group of potentially disabled individuals who might apply and qualify for disability insurance or other disability related benifits if they were to lose their jobs or to decide that employment offered an inadequate financial or non pecuniary reward thus disability or a health related inability to work is more than a medical problem but involves motivational and attitudinal factors we specify a model of the application process which we model as choice under uncertainty about approval of an application for disability insurance we specify the possible outcomes to the choice process of an individual in which the probability of acceptance for disability insurance is a key consideration we then estimate a joint model of labor supply and application to the disability insurance program based on the 1972 survey we then compare our results to the observed time series applications process since 1976 lastly we estimate the sensitivity of the application process to the probability of acceptance and the level of benifits

how debt markets have malfunctioned in the crisis the financial crisis that began in 2007 is especially a crisis in debt markets a full understanding of what happened in the financial crisis requires investigation into the plumbing of debt markets during a financial crisis when funds often cannot be raised easily or quickly the fundamental values for certain assets can become separated for a time from market prices with consequences that can echo into the real economy this article will explain in concrete ways how debt markets can malfunction with deleterious consequences for the real economy after a quick overview of debt markets i discuss three areas that are crucial in all debt markets decisions risk capital and risk aversion repo financing and haircuts and counterparty risk in each of these areas feedback effects can arise so that less liquidity and a higher cost for finance can reinforce each other in a contagious spiral i will document the remarkable rise in the premium that investors placed on liquidity during the crisis next i will show how these issues caused debt markets to break down indeed fundamental values and market values seemed to diverge across several markets and products that were far removed from the toxic subprime mortgage assets at the root of the crisis finally i will discuss briefly four steps that the federal reserve took to ease the crisis and how each was geared to a specific systemic fault that arose during the crisis

word of mouth communication and percolation in social networks this paper develops a model of demand pricing and advertising in the presence of social learning via word of mouth communication between friends in the model consumers must receive information about a monopolist s product in order to consider purchasing it the presence of word of mouth is not sufficient for demand to be more elastic and prices to be lower compared to an informed population i derive the comparative static results of connectivity mean preserving spread of friendships and clustering of friends on prices the optimal targets for advertising are not generically the individuals with the most friends jel l12 l14 a fundamental issue for economists is understanding the process by which demand is formed through social learning by consumers this article develops a framework based on random graphs for understanding the ways social learning via

the econometrics of kinked budget constraints in the last several years a branch of applied econometrics has developed which is devoted to the development of techniques for the estimation of demand and other functions when the budget constraint is piecewise linear or kinky that is when the constraint consists of a number of segments joined together at kink points such constraints most frequently arise from government tax and transfer programs for example the federal income tax imposes a piecewise linear schedule by the use of constant marginal tax rates within brackets a problem analyzed by hausman 1981 the payroll tax in the social security system likewise generates a kinked schedule inasmuch as the marginal tax rate on earnings is zero above a certain earnings maximum federal and state transfer programs for the poor result in piecewise linear constraints because transfer benefits are taxed in the sense of a negative income tax as income rises and because that tax rate falls to zero at the kink point where an individual or family loses eligibility for the benefit altogether many government transfer programs impose additional nonlinearities by altering this tax rate by discrete amounts over the range of positive benefits as well but kinked constraints sometimes arise in nongovernment contexts a well known example being the block pricing schedule commonly set by utilities and volume discounting in general kinked budget constraints create two difficulties that have several interesting facets one difficulty is that changes in tax and transfer schedules can have unexpected effects that can be exactly the opposite in sign to those expected from economic theory examples of this phenomenon are given below the second difficulty that with which this paper is mostly concerned relates to the implications of kinked budget

assessing systemic risk due to fire sales spillover through maximum entropy network reconstruction abstract monitoring and assessing systemic risk in financial markets is of great importance but it often requires data that are unavailable or available at a very low frequency for this reason systemic risk assessment with partial information is potentially very useful for regulators and other stakeholders in this paper we consider systemic risk due to fire sales spillovers and portfolio rebalancing by using the risk metrics defined by greenwood et al 2015 by using a method based on the constrained minimization of the cross entropy we show that it is possible to assess aggregated and single bank s systemicness and vulnerability using only the information on the size of each bank and the capitalization of each investment asset we also compare our approach with an alternative widespread application of the maximum entropy principle allowing to derive graph probability distributions and generating scenarios and we use it to propose a statistical test for a change in banks vulnerability to systemic events

dynamical macroprudential stress testing using network theory the increasing frequency and scope of nancial crises have made global nancial stability one of the major concerns of economic policy and decision makers this has led to the understanding that nancial and banking supervision has to be thought of as a systemic task focusing on the interdependent relations among the institutions using network theory we develop a dynamic model that uses a bipartite network of banks and their assets to analyze the system s sensitivity to external shocks in individual asset classes and to evaluate the presence of features underlying the system that could lead to contagion as a case study we apply the model to stress test the venezuelan banking system from 1998 to 2013 the introduced model was able to capture monthly changes in the structure of the system and the sensitivity of bank portfolios to dierent external shock scenarios and to identify systemic vulnerabilities and their time evolution the model provides new tools for policy makers and supervision agencies to use for macroprudential dynamical stress testing

social security disability insurance applications awards and lifetime income flows this article provides new evidence about the impact of social security disability insurance on male labor force participation decisions based on estimates from a structural model of applications awards and state contingent lifetime income flows the lifetime framework makes it possible to consider long term opportunity costs associated with early labor force withdrawal and the disincentive to applications resulting from the statutory waiting period before benefits may be received estimation techniques account for the self selected nature of the pool of applicants when predicting the individual specific probability of acceptance and the opportunity costs of applying

the decline in male labor force participation comment in an article in thisjournal parsons 1980a analyzes the doubling in the rate of nonparticipation in the labor force of older men since 1946 using cross sectional data from the national longitudinal survey parnes et al 1970 in an index function model of the labor force participation decision he tests the assertion that the withdrawal of older males is attributable to the rapid expansion of alternatives to work provided by the social security disability insurance ssdi program he reports an elasticity of nonparticipation with respect to the replacement rate of ssdi benefits of 631 and concludes that the recent decline in labor force participation can be largely explained by the increased generosity of social welfare transfers particularly social security disability payments p 130 the magnitude of parsons s estimate and its impact on the public debate over disability transfer policy require careful scrutiny of its basis in section i we describe parsons s econometric model and construction of variables in section ii we provide a critique in section iii we test the robustness of parsons s elasticity estimate by presenting alternative estimates based on corrections and extensions of his basic model section iv concludes

on the availability of relevant costs information in operations management abstract the operations management om function is amongst others held responsible for in time delivery of customer orders against minimal costs from a management accounting point of view all decisions which are made to fulfil this function can be evaluated against relevant costs this would imply that for each decision management must take into consideration all possible variable costs and opportunity costs at the operational level variable costs consist of capacity costs such as work in overtime and inventory carrying costs opportunity costs may arise if promised delivery dates cannot be met in practice this om function is often partially performed by materials management production management and or physical distribution management moreover in an engineer to order production situation engineering management and related areas e g process planning are also involved in each stage of production physical or non physical decisions concerning internal delivery dates utilization of capacity and inventory may occur research was carried out to find out whether management is actually provided with relevant costs information to evaluate these operational decisions therefore case study research in eight dutch industrial firms was carried out it concerned small to medium sized firms 80 250 employees firms all producing rather complex machines for industrial markets production control situations varied between assemble to order and engineer to order the case studies were carried out in a highly structured manner it occurred that all kinds of relevant costs information was missing or not known to the management in charge missing information concerned internal and external delivery performance actual inventory and wip levels and actual utilization of capacity furthermore it arose that all kinds of standards were unreliable from a management accounting perspective the results of the case study research indicate that relevant costs decision making is al least not very common in practice if relevant costs are partially missing managers will decide using other irrelevant information we feel that this might perhaps be an explanation for the growing discontent that the management accounting is confronted with

disability transfers and the work decision of older men the potential causal relationship between the availability and generosity of disability transfers and the nonparticipation rates of older men is often asserted and much studied parsons 1980 haveman and wolfe 1984 leonard 1986 however estimates of the magnitude of this linkage vary widely the growth in transfer availability and generosity has been credited with from 30 to 100 percent of the significant post 1960 fall in older male participation rates the disparity in these research results stems primarily from 1 alternative sources of data that differentially constrain estimation of relevant expected wage and transfer incomes 2 specifications that are unable to distinguish income transfer from labor market effects and 3 reliance on measures of health status that are endogenous to the work leisure decision this study seeks to narrow the range of estimates by addressing each of these issues our utility maximization model of work status choice assumes that workers who differ in health status choose between the mutually exclusive options of working at the wage offered for their characteristics and accepting public or private disability transfers because the income flows in the two options are censored they are estimated using switching regression techniques as expectations conditional on exogenous individual characteristics hence accounting for the potentially endogenous process that separates wage earners from transfer recipients the marginal utilities of income from the two sources are allowed to differ because of stigma effects in the estimation we adjust the choice based nature of our sample employ longitudinal earnings data to measure expected changes in as distinct from the expected level of income in the two options and use a separately estimated latent health status measure largely purged of its endogeneity with the participation decision

when micro prudence increases macro risk the destabilizing effects of financial innovation leverage and diversification by exploiting basic common practice accounting and risk management rules we propose a simple analytical dynamical model to investigate the effects of microprudential changes on macroprudential outcomes specifically we study the consequence of the introduction of a financial innovation that allows reducing the cost of portfolio diversification in a financial system populated by financial institutions having capital requirements in the form of value at risk var constraint and following standard mark to market and risk management rules we provide a full analytical quantification of the multivariate feedback effects between investment prices and bank behavior induced by portfolio rebalancing in presence of asset illiquidity and show how changes in the constraints of the bank portfolio optimization endogenously drive the dynamics of the balance sheet aggregate of financial institutions and thereby the availability of bank liquidity to the economic system and systemic risk the model shows that when fin

the rise in the disability rolls and the decline in unemployment between 1984 and 2001 the share of nonelderly adults receiving social security disability insurance income di rose by 60 percent to 5 3 million beneficiaries rapid program growth despite improving aggregate health appears to be explained by reduced screening stringency declining demand for less skilled workers and an unforeseen increase in the earnings replacement rate we estimate that the sum of these forces doubled the labor force exit propensity of displaced high school dropouts after 1984 lowering measured u s unemployment by one half a percentage point steady state calculations augur a further 40 percent increase in the rate of di receipt

optimal safety stock levels of subassemblies and manufacturing components abstract in order to control the time to market and manufacturing costs companies produce and purchase many parts and components before receiving customer orders consequently demand forecasting is a critical decision process using modular product design and super bills of materials are two effective strategies for developing a reliable demand forecasting process they reduce the probability of stockouts in diversified production contexts furthermore managing and controlling safety stocks for pre assembled modules provide an effective solution to the problem of minimizing the effects of forecast errors this paper develops evaluates and applies innovative cost based analytical models so that the optimal safety stock of modular subassemblies and components in assembly to order and manufacturing to order systems respectively can be rapidly quantified the implementation of the proposed models in two industrial case applications demonstrates that they significantly reduce the safety stock inventory levels and the global logistical cost

the economic implications of public disability insurance in the united states a review of previous analyses of labor supply effects of social security disability insurance di concludes that estimates of labor supply effects and net social costs are upward biased because they ignore interactions between di and other insurances a model of optimal insurance postinjury accommodations and labor supply shows that reduction in labor supply and increase in consumption when disabled do not necessarily imply moral hazard optimal postinjury accommodations vary inversely with firm size the americans with disabilities act will reduce wages and labor supply of healthy workers particularly in small firms effects on labor supply of the disabled are ambiguous

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

a macroprudential approach to financial regulation many observers have argued that the regulatory framework in place prior to the global financial crisis was deficient because it was largely microprudential in nature a microprudential approach is one in which regulation is partial equilibrium in its conception and aimed at preventing the costly failure of individual financial institutions by contrast a macroprudential approach recognizes the importance of general equilibrium effects and seeks to safeguard the financial system as a whole in the aftermath of the crisis there seems to be agreement among both academics and policymakers that financial regulation needs to move in a macroprudential direction in this paper we offer a detailed vision for how a macroprudential regime might be designed our prescriptions follow from a specific theory of how modern financial crises unfold and why both an unregulated financial system as well as one based on capital rules that only apply to traditional banks is likely to be fragile we begin by identifying the key market failures at work why individual financial firms acting in their own interests deviate from what a social planner would have them do next we discuss a number of concrete steps to remedy these market failures we conclude the paper by comparing our proposals to recent regulatory reforms in the united states and to proposed global banking reforms

the health and earnings of rejected disability insurance applicants applicants for social security disability benefits who fail to pass the medical screening form a natural control group for beneficiaries data drawn from the 1972 and 1978 surveys of the disabled done for the social security administration show that fewer than 50 percent of rejected male applicants work typical earnings of those that do are less than 59 percent of median earnings for other men their age these data cast doubt on recent econometric work that suggests that the disincentive effects of the social security disability program have been substantial copyright 1989 by american economic association

reconstructing and stress testing credit networks abstract financial networks are an important source of systemic risk but often only partial network information is available in this paper we use data on bank firm credit relationships in japan and conduct a horse race between different network reconstruction methods in terms of their ability to reproduce the actual credit networks we then compare the different reconstruction methods in terms of their implied levels of systemic risk based on a standard model of price mediated contagion we find that the observed credit network displays relatively high levels of systemic risk compared with most reconstruction methods lastly we explore whether different policies can improve the robustness of the system

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 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

monitoring indirect contagion abstract we propose two indicators for quantifying the potential exposure of financial institutions to indirect contagion arising from deleveraging of assets in stress scenarios the first indicator the endogenous risk index eri captures spillovers across portfolios arising from deleveraging in stress scenarios the second indicator the indirect contagion index ici measures the systemic importance of a bank by quantifying the loss its distressed liquidation would inflict on other institutions both are computable from portfolio holdings of financial institutions and measures of market depth for the assets held in the portfolio we discuss the micro foundation of these indicators and apply them to the analysis of the vulnerability of the european banking system to indirect contagion using data on portfolio holdings of european banks we show that our indicators correlate to the magnitude of fire sales losses in simulated stress scenarios thus providing a simple to compute proxy for the outcome of stress tests we also show that the information provided by our indicators on the systemic importance of banks is different from indicators based on size thereby providing a measure of interconnectedness complementary to those currently used by supervisors

disability insurance rejection rates and the labor supply of older workers abstract we investigate the effects of trying to mitigate moral hazard in the disability insurance di program by raising the stringency of the screening process for applicants we do so by studying a dramatic increase in rejection rates for the di program in the late 1970s which varied substantially across the us states we find that each 10 rise in denial rates led to a statistically significant 2 8 fall in labor force non participation among 45 64 year old males we also find that the denial rate increases effectively targeted their incentive effects to more able individuals according to an anthropometric measure of disability

a life cycle model of unemployment and disability insurance abstract a general equilibrium life cycle model is developed in which individuals choose a sequence of saving and labor supply faced with search frictions and uncertainty in longevity health status and medical expenditures unemployed individuals decide whether to apply for disability insurance di benefits if eligible we investigate the effects of cash transfer and in kind medicare component of the di system on the life cycle employment without medicare benefits di coverage could fall significantly we also study how di interacts with reforms of social security and medicare and find that di enrollment amplifies the effects of reforms

forward looking solvency contagion abstract solvency contagion risk is a key channel through which systemic risk can come about we introduce a model that accounts not only for losses transmitted after banks default but also for losses due to the fact that creditors revalue their exposures when probabilities of default of their counterparties change we apply the model to run a series of simplified stress tests of the uk banking system from 2008 to 2016 based on two datasets of real interbank exposures between the seven major uk banks we show that risks due to solvency contagion decrease markedly from the peak of the crisis to the point of becoming negligible we also characterise the distributions of both vulnerabilities and systemic importances of individual banks thereby tracking the evolution of risk concentration

asset commonality debt maturity and systemic risk we develop a model in which asset commonality and short term debt of banks interact to generate excessive systemic risk banks swap assets to diversify their individual risk two asset structures arise in a clustered structure groups of banks hold common asset portfolios and default together in an unclustered structure defaults are more dispersed portfolio quality of individual banks is opaque but can be inferred by creditors from aggregate signals about bank solvency when bank debt is short term creditors do not roll over in response to adverse signals and all banks are ine ciently liquidated this information contagion is more likely under clustered asset structures in contrast when bank debt is long term welfare is the same under both asset structures

how do unemployment insurance benefits affect the decision to apply for social security disability insurance this paper examines whether unemployment insurance ui benefits affect the decision to apply for social security disability insurance di using data from the survey of income and benefits matched to administrative records on di applications i find that higher ui benefits reduce applications for di this substitution effect is imprecisely estimated but economically significant implying that a 1 00 increase in ui benefits reduces di expenditures by 15 cents recognizing this cost saving effect would increase the optimal ui benefit level by more than 20 percent for coefficients of relative risk aversion ranging from two to five

the welfare implications of increasing disability insurance benefit generosity abstract in order to evaluate whether workers are over or under insured through the disability insurance di program we develop a framework that allows us to simulate the benefits as well as the costs associated with marginal changes in payment generosity from a representative cross sectional sample of the population under the assumption that individuals are reasonably risk averse we find that the typical worker would value increased benefits somewhat above the average costs of providing them however whether the benefit increases tend to lower or raise utility when we average across all individuals in our sample is sensitive to assumptions that affect the relative marginal utility of income to disabled individuals

the impact of systemic and illiquidity risk on financing with risky collateral abstract repurchase agreements repos are one of the most important sources of funding liquidity for many financial investors and intermediaries in a repo some assets are given by a borrower as collateral in exchange of funding the capital given to the borrower is the market value of the collateral reduced by an amount termed as haircut or margin the haircut protects the capital lender from loss of value of the collateral contingent on the borrower s default for this reason the haircut is typically calculated with a simple value at risk estimation of the collateral for the purpose of preventing the risk associated to volatility however other risk factors should be included in the haircut and a severe undervaluation of them could result in a significant loss of value of the collateral if the borrower defaults in this paper we present a stylized model of the financial system which allows us to compute the haircut incorporating the liquidity risk of the collateral and most important possible systemic effects these are mainly due to the similarity of bank portfolios excessive leverage of financial institutions and illiquidity of assets the model is analytically solvable under some simplifying assumptions and robust to the relaxation of these assumptions as shown through monte carlo simulations we also show which are the most critical model parameters for the determination of haircuts

measuring network systemic risk contributions a leave one out approach abstract the aim of this paper is to propose a new network measure of systemic risk contributions that combines the pair wise granger causality approach with the leave one out concept this measure is based on a conditional granger causality test and consists of measuring how far the proportion of statistically significant connections in the system breaks down when a given financial institution is excluded we analyse the performance of our measure of systemic risk by considering a sample of the largest banks worldwide over the 2003 2018 period we obtain three important results first we show that our measure is able to identify a large number of banks classified as global systemically important banks g sibs by the financial stability board fsb second we find that our measure is a robust and statistically significant early warning indicator of downside returns during the last financial crisis finally we investigate the potential determinants of our measure of systemic risk and find similar results to the existing literature in particular our empirical results suggest that the size and the business model of banks are significant drivers of systemic risk

aching to retire the rise in the full retirement age and its impact on the social security disability rolls abstract the social security amendments of 1983 reduced the generosity of social security retired worker benefits in the u s by increasing the program s full retirement age from 65 to 67 and increasing the penalty for claiming benefits at the early retirement age of 62 these changes were phased in gradually so that individuals born in or before 1937 were unaffected and those born in 1960 or later were fully affected no corresponding changes were made to the program s disabled worker benefits and thus the relative generosity of social security disability insurance ssdi benefits increased in this paper we investigate the effect of the amendments on ssdi enrollment by exploiting variation across birth cohorts in the policy induced reduction in the present value of retired worker benefits our findings indicate that the amendments significantly increased ssdi enrollment since 1983 with an additional 0 6 of men and 0 9 of women between the ages of 45 and 64 receiving ssdi benefits in 2005 as a result of the changes our results further indicate that these effects will continue to increase during the next two decades as those fully exposed to the reduction in retirement benefit generosity reach their fifties and early sixties

minimum cost safety stocks for frequent delivery manufacturing abstract the lot size reduction in production and purchasing intensifies the exposure to stockouts material and product safety stocks must be held to prevent production hampering and poor delivery performance to customers safety stocks reduce opportunity costs caused by delayed deliveries but significantly increase inventory costs this paper presents an analytical solution for an optimization model that determines whenever it is preferable to incur inventory or opportunity costs an application is presented to illustrate the solution

capital regulation under price impacts and dynamic financial contagion abstract we construct a continuous time model for price mediated contagion precipitated by a common exogenous stress to the banking book of all firms in the financial system in this setting firms are constrained so as to satisfy a risk weight based capital ratio requirement we use this model to find analytical bounds on the risk weights for assets as a function of the market liquidity under these appropriate risk weights we find existence and uniqueness for the joint system of firm behavior and the asset prices we further consider an analytical bound on the firm liquidations which allows us to construct exact formulas for stress testing the financial system with deterministic or random stresses numerical case studies are provided to demonstrate various implications of this model and analytical bounds

disability benefit generosity and labor force withdrawal abstract a key component for estimating the optimal size and structure of disability insurance di programs is the elasticity of di claiming with respect to benefit generosity yet in many countries including the united states all workers face identical benefit schedules which are a function of one s labor market history making it difficult to separate the effect of the benefit level from the effect of unobserved preferences for work on individuals claiming decisions to circumvent this problem we exploit exogenous variation in di benefits in austria arising from several reforms to its di and old age pension system in the 1990s and 2000s we use comprehensive administrative social security records data on the universe of austrian workers to compute benefit levels under six different regimes allowing us to identify and precisely estimate the elasticity of di claiming with respect to benefit generosity we find that over this time period a 1 increase in potential di benefits was associated with a 1 2 increase in di claiming

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

when panic makes you blind a chaotic route to systemic risk abstract we present an analytical model to study the role of expectation feedbacks and overlapping portfolios on systemic stability of financial systems building on corsi et al 2016 we model a set of financial institutions having value at risk capital requirements and investing in a portfolio of risky assets whose prices evolve stochastically in time and are endogenously driven by the trading decisions of financial institutions assuming that they use adaptive expectations of risk we show that the evolution of the system is described by a slow fast random dynamical system which can be studied analytically in some regimes the model shows how the risk expectations play a central role in determining the systemic stability of the financial system and how wrong risk expectations may create panic induced reduction or over optimistic expansion of balance sheets specifically when investors are myopic in estimating the risk the fixed point equilibrium of the system breaks into leverage cycles and financial variables display a bifurcation cascade eventually leading to chaos we discuss the role of financial policy and the effects of some market frictions as the cost of diversification and financial transaction taxes in determining the stability of the system in the presence of adaptive expectations of risk

financial contagion and economic development an epidemiological approach abstract we develop an epidemiological approach to analyze how financial contagion may affect and be affected by economic activity we show that according to specific parameter values the economy may converge either to a non speculative or to a speculative equilibrium in the former situation the level of per capita income is maximal while in the latter it is reduced by financial contagion the presence of economic and financial feedback effects may also give rise to macroeconomic fluctuations during the transitional path clearly showing that such economic and financial links are an important driver of the short run macroeconomic performance by extending the analysis to a spatial dimension we also show that financial contagion in some specific region may propagate quickly also in regions far away from those in which the contagion initially occurs highlighting the role of regional policy coordination to avoid interregional contagion

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