energy disruptions interfirm price effects and the aggregate economy in an economy with many imperfect competitors monopolistic competition firms that pass through higher oil prices during a disruption will affect the demand for firms in other industries firms that charge higher prices for their final product will include the effect on their own final product in their private decisions but will exclude the effect on the final products of other firms although a pecuniary externality these actions will reduce society s welfare unlike the case of a perfectly competitive market this situation creates a societal risk that is much wider than an externality in any single market policy interest shifts from one of punishing persian gulf oil producers to one of cushioning an industrialized economy from sudden disruptions caused by political and military conflicts although the value of reducing oil use depends upon a number of unknown parameters with wide distributions a representative numerical example suggests that it may approach 5 per barrel

oil price shocks and the macroeconomy this paper examines the impact of oil price shocks and attempts to explain why the rise in oil prices up to 2008 had little impact on the world economy it makes three main arguments first that oil prices have never been as important as is popularly thought second that the most important route through which oil prices affect output is monetary policy when oil prices pass through to core inflation monetary authorities raise interest rates slowing growth based on the second argument the third argument is that high oil prices have not reduced growth in recent years because they no longer pass through to core inflation so the monetary tightening previously seen in response to high oil prices is absent it also argues that oil prices had little impact on the global recession of 20089

the effects of oil price shocks on expenditure category cpi in this study we apply a two block structural vector autoregressive var model proposed by kilian and park 2009 in order to investigate the dynamic effects of changes in oil price on the expenditure category consumer price index cpi in the united states and japan our results confirm that each expenditure category price index responded very differently to the same structural shock and that whether changes in oil price function as a positive stimulus or a negative shock for the individual expenditure category prices also depends on the kind of underlying shock that drives the changes in oil price finally our results also reveal that the manner in which changes in oil price affect each expenditure category price differs between the united states and japan and these detailed level differences may lead to aggregate level differences in the price response of both countries to changes in oil price

why would a durable good monopolist also produce a cost inefficient nondurable good abstract we develop both commitment and time consistent stationary policies for a monopolist who produces a mixture of goods distinguished by production costs and degree of durability under commitment only the cost efficient durable good is produced and the monopoly output is realized each period for the time consistent stationary case there is an interval for the degree of durability where only the durable good is produced and a higher non overlapping interval where both the cost efficient durable and the cost inefficient nondurable good are produced for any period length when the degree of durability is such that both durable and nondurable goods are provided combined output is less than the competitive output and decreases in the degree of durability approaching the single period monopoly output when both goods are produced the coase conjecture does not hold

the coase conjecture need not hold for durable good monopolies with depreciation abstract we consider the optimal sales policy for a monopoly seller of a durable good in a non stationary rational expectations equilibruim with replacement sales we show that coase s conjecture that the monopolist will sell the competitive stock as period length approaches zero may not hold under these assumptions

durable goods oligopoly abstract this paper models a durable goods oligopoly as a differential game two cases are treated sales where firms cannot lease but must sell the good in question and leasing where firms do not sell but only rent in the sales case firms face increasing marginal cost of production and the good in question depreciates for this case a rational expectations feedback nash equilibrium is constructed for which monopoly or oligopoly output is less than the efficient level this gap between oligopoly and competitive output diminishes as the number of firms increases when firms can only lease the good the good is assumed not to depreciate and the monopoly level of steady state output is compared with the level of steady state output for a feedback equilibrium duopoly for this case the duopoly equilibrium has steady state output that is less than the corresponding efficient level but greater than the monopoly level the leasing model is shown to be isomorphic to the adjustment cost duopoly model of driskill and mccafferty journal of economic theory 49 1989 324 338

the role of energy in real business cycle models abstract this paper modifies hansen s 1985 analysis of a real business cycle mode with indivisible labor by explicitly including energy as a productive input and modelling the relative price of energy as an exogenous random process one goal is to determine the extent to which the introduction of energy price shocks reduces the reliance of the real business cycle model on unobserved technology shocks the other goal following christiano and eichenbaum 1991 is to compare the correlation between real wages and hours predicted by the energy inclusive model to that predicted by hansen s model

foundations of dynamic monopoly and the coase conjecture subgame perfect equilibria are characterized for a market in which the seller quotes a price each period assume zero costs positive interest rate continuum of buyers and some technical conditions if buyers valuations are positive then equilibrium is unique buyers strategies are stationary and the price sequence is determinant along the equilibrium path but possibly randomized elsewhere otherwise a continuum of stationary equilibria can exist but at most one with analytic strategies coase s conjecture is verified for stationary strategies reducing the period length drives all prices to zero or the least valuation connections to bargaining models are described journal qf economic literature classification

unemployment equilibria and input prices theory and evidence from the united states the paper develops an efficiency wage model where input prices affect the equlibrium rate of unemployment we show that a simple framework based on only two prices the real price of oil and the real rate of interest is able to explain the main post war movements in the rate of u s joblessnss the equations do well in forecasting unemployment many out of sample and provide evidence that the oil price spike associated with iraq s invasion of kuweit appears to be a component of the mystery recession which followed

oil and the macroeconomy since world war ii all but one of the u s recessions since world war ii have been preceded typically with a lag of around three fourths of a year by a dramatic increase in the price of crude petroleum this does not mean that oil shocks caused these recessions evidence is presented however that even over the period 1948 72 this correlation is statistically significant and nonspurious supporting the proposition that oil shocks were a contributing factor in at least some of the u s recessions prior to 1972 by extension energy price increases may account for much of post opec macroeconomic performance

crude oil and the macroeconomy tests of some popular notions a note perhaps no other economic events in the post world war ii era have generated as much attention as the series of crude oil price shocks that have jolted the world economy since the opec boycott of 1973 a tremendous amount of space in the popular and professional literature has been devoted to analyzing the impacts of these shocks on the developed economies and the adjustments these shocks have induced one residual of this literature has been a general impression that since 1973 the functional relationship between crude oil prices and the developed macroeconomies has been dramatically and fundamentally altered yet to our knowledge no one has formally tested this impression recent evidence of hamilton 1983 suggests that crude oil prices had a strong impact on the u s business cycle well before 1973 further while textbook treatments of oil price shocks tend to highlight cost push inflationary effects the research of berndt and wood 1975 1979 and wilcox 1983 indicates the net complementarity between energy and capital in the u s economy is quite strong both before and after 1973 thus oil price shocks may have stronger real effects than generally believed in this paper we formally test three popular notions associated with the so called

durable good monopoly and best price provisions best price provisions guarantee buyers that the prices they pay are the lowest available if the seller subsequently cuts price then each previous buyer is entitled to a refund a durable good monopolist who offers certain forms of these provisions can construct a consistent plan yielding the same profits as rental agreements and contracts with explicit quantity commitments the provisions require special circumstances to be practical but they are simple and effective and appear in a variety of economic settings three applications are discussed international commodity agreements markets for electric turbogenerators and markets for financial claims copyright 1990 by american economic association

network effects aftermarkets and the coase conjecture a dynamic markovian approach this paper investigates the expansion of the network of a monopolist firm that produces a durable good and is also involved in the corresponding aftermarket we characterize the markov perfect equilibrium of the continuous time dynamic game played by the monopolist and the forward looking consumers under the assumption that consumers benefit from the subsequent expansion of the network the paper contributes to the theoretical discussion on the validity of the coase conjecture analyzing whether coase s prediction that the monopolist serves the market in a twinkling of an eye remains valid in our setup we conclude that the equilibrium network development may actually be gradual contradicting coase s conjecture we find that a necessary condition for such a result is the existence of aftermarket network effects that accrue at least partly to the monopolist firm

imperfect competition and the effects of energy price increases on economic activity the authors show that modifying the standard neoclassical growth model by assuming that competition is imperfect makes it easier to explain the size of the declines in output and real wages that follow increases in the price of oil plausibly parameterized models of this type are able to mimic the response of output and real wages in the united states the responses are particularly consistent with a model of implicit collusion where markups depend positively on the ratio of the expected present value of future profits to the current level of output copyright 1996 by ohio state university press

oil and stock market volatility a multivariate stochastic volatility perspective abstract this paper models the volatility of stock and oil futures markets using the multivariate stochastic volatility structure in an attempt to extract information intertwined in both markets for risk prediction it offers four major findings first the stock and oil futures prices are inter related their correlation follows a time varying dynamic process and tends to increase when the markets are more volatile second conditioned on the past information the volatility in each market is very persistent i e it varies in a predictable manner third there is inter market dependence in volatility innovations that hit either market can affect the volatility in the other market in other words conditioned on the persistence and the past volatility in their respective markets the past volatility of the stock oil futures market also has predictive power over the future volatility of the oil futures stock market finally the model produces more accurate value at risk estimates than other benchmarks commonly used in the financial industry

sectoral shifts and cyclical unemployment a substantial fraction of cyclical unemployment is better characterized as fluctuations of the frictional or natural rate than as deviations from some relatively stable natural rate shifts of employment demand between sectors of the economy necessitate continuous labor reallocation since it takes time for workers to find new jobs some unemployment is unavoidable this paper presents evidence that most of the unemployment fluctuations of the seventies unlike those in the sixties were induced by unusual structural shifts within the u s economy simple time series models of layoffs and unemployment are constructed that include a measure of structural shifts within the labor market these models are estimated and a derived natural rate series is constructed

oil shocks and monetary policy rules in emerging economies we examine the effects of shocks in the oil market on key macroeconomic variables in small open economies using a dynamic stochastic general equilibrium model with sticky prices and imperfect competition under different monetary policy rules the numerical solutions show that the types of exchange rate regimes and monetary policies could partly explain the trends in macroeconomic volatilities considering negative shocks to oil supply hamilton 1983 and positive shocks to oil demand kilian 2009 these findings are confirmed in vector autoregressive responses for chile and israel with inflation targeting under flexible exchange regimes and hong kong with fixed regime

reputation in bargaining and durable goods monopoly this paper analyzes durable goods monopoly in an infinite horizon discrete time game we prove that as the time interval between successive offers approaches zero all seller payoffs between zero and static monopoly profits are supported by subgame perfect equilibria this reverses a well known conjecture of coase alternatively one can interpret the model as a sequential bargaining game with one sided incomplete information in which an uninformed seller makes all the offers our folk theorem for seller payoffs equally applies to the set of sequential equilibria of this bargaining game

imperfect competition and business cycles an empirical investigation imperfect competition and business cycles an empirical investigation does imperfect competition increase the magnitude of business cycles if so the variability of an industry s employment and output should be positively related to the market power of firms in that industry this paper demonstrates that the opposite is true u s manufacturing industries with high price cost margins display less employment variability than do low markup industries these high markup industries display less price variability as well highly concentrated industries however do display more employment variability to some degree markups may reflect labor hoarding rather than market power this may account for part but not all of the negative correlation between markups and variability i introduction recent research has investigated whether deviations from perfect competition either in goods or labor markets help explain the existence and magnitude of business cycles in particular both theoretical and empirical evidence suggests that imperfectly competitive firms hold prices more rigid in the face of demand shocks than do more competitive firms 1 this finding raises the question of whether imperfectly competitive industries also exhibit larger fluctuations in output and employment this paper examines employment and output data for 446 u s manufacturing industries over the years 1958 to 1984 if employment and output fluctuations have been smaller in more competitive industries this would suggest that imperfect competition may indeed lead to larger business cycle fluctuations in fact my results suggest the opposite industries with larger price marginal cost margins display less variability in employment and output although the output results are not robust the finding for employment is remarkably robust to a wide range of specifications in particular it holds for two different methods of estimating the price marginal cost margin in contrast i find that highly concentrated industries as opposed to those with high price marginal cost margins do display more variability in output and employment than do less concentrated industries in addition i confirm the finding of previous studies that industries with high price cost margins display less price variability thus it appears that imperfect competition may reduce variability in both prices and quantities the paper proceeds as follows section ii outlines the theoretical literature and surveys previous empirical work in this area section iii describes the methodology of the paper and section iv describes the estimation of the price marginal cost margin section v presents the results and section vi discusses possible explanations section vii concludes ii theoretical literature and previous work many theoretical models suggest that imperfectly competitive industries ought to display more cyclical variability of output than perfectly competitive industries the common thread in all these theories is real price rigidity 2 some reason is offered why an imperfectly competitive firm does not adjust its relative price in response to a demand shock as much as would a perfectly competitive firm the less prices adjust the more output and employment must adjust therefore the argument goes imperfect competition may exacerbate the size of business cycle fluctuations 3 this basic argument dates back to means 1935 prices may be relatively acyclical or even countercyclical in industries with market power for one of two reasons either marginal cost is relatively flat or markups are relatively countercyclical the following theories of real price rigidity may be classified as falling into one of these two categories firms with market power are assumed to maintain excess capacity perhaps as a barrier to entry by new firms

oil price shocks and the dispersion hypothesis recent research by david lilien shows that a significant fraction of aggregate unemployment can be explained by the dispersion of employment growth across industries this paper presents two new results in this area first it is shown that a significant fraction of the variation in lilien s dispersion index is due to the differential impact of oil shocks across industries second and more important it is shown that once the dispersion in employment growth due to oil shocks is accounted for the residual dispersion has no explanatory power for unemployment

monopoly with endogenous durability abstract a multi period formulation for a durable good monopoly is developed where production and durability are decision variables when commitment to production is possible neither the level nor the depreciation rate of initial stock has an effect on the selected efficient degree of durability with time consistent production policy the optimal degree of durability is less than the efficient rate and typically increasing in the initial stock and initial degree of durability when a monopolist can switch at any time from an inefficient non durable to an efficient durable there exists a cutoff durability above which only the non durable will be produced otherwise the efficient durable will be produced

does the source of oil price shocks matter for south african stock returns a structural var approach abstract in this paper we investigate the dynamic relationship between different oil price shocks and the south african stock market using a sign restriction structural var approach for the period 1973 01 to 2011 07 the results show that for an oil importing country like south africa stock returns only increase with oil prices when global economic activity improves in response to oil supply shocks and speculative demand shocks stock returns and the real price of oil move in opposite directions the analysis of the variance decomposition shows that the oil supply shock contributes more to the variability in real stock prices the main conclusion is that different oil price shocks affect stock returns differently and policy makers and investors should always consider the source of the shock before implementing a policy and making investment decisions

oil price fluctuations and u s dollar exchange rates adding oil prices to the monetary model of exchange rates we find that oil prices significantly explain movements in the value of the u s dollar usd against major currencies from the 1970s to 2008 our long run and forecasting results are remarkably consistent with an oil exchange rate relationship increases in real oil prices lead to a significant depreciation of the usd against net oil exporter currencies such as canada mexico and russia on the other hand the currencies of oil importers such as japan depreciate relative to the usd when the real oil price goes up

nonconvex costs and the behavior of inventories this paper explores one possible explanation for the apparent excess volatility of production relative to sales nonconvexities in the technology facing firms it is shown that if firms operate in a region of declining marginal costs then small shifts in demand can cause production to jump substantially estimates for six production to stock industries as well as the automobile industry suggest that all these industries behave as if they were operating in the region of nonconvex costs the results have important implications not only for inventory investment but also for the cyclical behavior of productivity and prices

a dynamic inventory model with the right of refusal we consider a dynamic inventory production model with general convex order production costs and excess demand that can be accepted or refused by the firm excess demand that is accepted is backlogged and results in a backlog cost whereas demand that is refused results in a lost sales charge endogenizing the sales decision is appropriate in the presence of general convex order costs so that the firm is not forced to backlog a unit whose subsequent satisfaction would reduce total profits in each period the firm must determine the optimal order and sales strategy we show that the optimal policy is characterized by an optimal buy up to level that increases with the initial inventory level and an order quantity that decreases with the initial inventory level more importantly we show the optimal sales strategy is characterized by a critical threshold a backlog limit that dictates when to stop selling this threshold is independent of the initial inventory level and the amount purchased we investigate various properties of this new policy as demand stochastically increases the amount purchased increases but the amount backlogged decreases reflecting a shift in the way excess demand is managed we develop two regularity conditions one that ensures some backlogs are allowed in each period and another that ensures the amount backlogged is nondecreasing in the length of the planning horizon we illustrate the buy up to levels in our model are bounded above by buy up to levels from the pure lost sales and pure backlogging models we explore additional extensions using numerical experiments

dynamic cyclical comovements between oil prices and us gdp a wavelet perspective abstract in this paper we use wavelet analysis to investigate the cyclical comovements between crude oil prices and us gdp taking into account the decline in the volatility of us gdp growth that has occurred since the mid 1980s our main findings suggest that before 1984 q1 the crude oil prices were leading the us gdp cycle by 3 quarters and granger cause us gdp in contrast after 1984 q1 the crude oil prices were lagging the us business cycle and a reverse causality is found to run from us gdp to oil prices the multiscale granger causality tests globally corroborate theses results

realized volatility transmission between crude oil and equity futures markets a multivariate har approach this paper differs from extant literature because it studies volatility co movements with a multivariate orthogonalized har model a flexible specification for the time series of realized volatility which is able to identify short mid and long term spillover effects we examine volatility transmission mechanisms using high frequency data of the stock index futures on s p 500 nikkei 225 ftse 100 and the futures on the west texas intermediate crude oil during the period from september 2002 to september 2012 considering the full sample the short term volatility of the equity futures contains information about future oil volatility incremental to the information inherent in the time series of oil volatility on the other hand weekly and monthly volatilities do not exhibit a significant spillover effect breaking the whole sample into three subsamples no significant granger causalities are observed in the pre crisis period while in the crisis time and its aftermath we document that the us and uk equity market volatilities to granger cause the oil futures volatility which itself leads the japanese market in terms of magnitude we observe an increase in the short term volatility spillover over time studying the residuals of the har transmission models within a ccc dcc garch framework reveals increasing instantaneous correlation between the energy and equity volatilities in the course of time

strategic entry in a triopoly market of firms with asymmetric cost structures abstract this paper examines the strategic investment timing decision in a triopoly market comprising firms with asymmetric cost structures we present three novel results first in the case where there are relatively small cost asymmetries between firms and a relatively small first mover advantage the firm with the lowest cost structure is not always the first investor in other cases the firm with the lowest cost structure is the first investor second an increase in volatility increases the possibility that a firm without the lowest cost structure is the first investor finally even in the three asymmetric firm model we show that the first investor threshold is larger in a triopoly than in a duopoly although it is smaller in a duopoly than in a monopoly

monopoly extraction of a durable non renewable resource failure of the coase conjecture the author studies a perfect information rational expectations markov equilibrium for the situation where a monopolist extracts a nonrenewable resource that is converted to a durable good even if short run extraction costs are constant the coase conjectur e fails provided that the depreciation rate of the durable good is positive copyright 1993 by the london school of economics and political science

a neoclassical model of unemployment and the business cycle this paper investigates a general equilibrium model of unemployment and the business cycle in which specialization of labor plays a key role a rational expectations equilibrium with fully flexible wages and prices can exhibit unemployment in which the marginal product of employed workers exceeds the reservation wage of those who are without jobs workers are unemployed either because they are in the process of relocating for a better job or because they are waiting for conditions in the depressed sector to improve moreover seemingly small disruptions in the supplies of primary commodities such as energy could be the source of fluctuations in aggregate employment and can exert surprisingly large effects on real output

input price shocks and the slowdown in economic growth the case of u k manufacturing this paper provides a theoretical and empirical analysis of the effects of input price shocks on economic growth with a focus on united kingdom manufacturing in the 1970s the theoretical model predicts a discrete decline in output and productivity after an input price rise and a longer run slowdown in productivity growth real wage growth and capital accumulation these features characterize the united kingdom and most other oecd economies after 1973 the empirical results confirm the important role of input prices in recent u k adjustment but also point to an important role for other supply and demand factors two types of explanations have been offered for the sharp deterioration in u k economic performance in the past decade focusing respectively on demand and supply factors a standard keynesian view holds that macroeconomic demand management has been either too expansionary or too contractionary and that rising unemployment and falling output reflect the burden of anti inflationary policies an alternative view holds that various supply shocks are the main source of the poor output performance in this interpretation higher raw material prices particularly oil competition from the newly industrializing countries nics and perhaps an independent decline in productivity growth all have lowered output growth and raised unemployment

oil price shocks and stock markets in the u s and 13 european countries abstract oil price shocks have a statistically significant impact on real stock returns contemporaneously and or within the following month in the u s and 13 european countries over 1986 1 2005 12 norway as an oil exporter shows a statistically significantly positive response of real stock returns to an oil price increase the median result from variance decomposition analysis is that oil price shocks account for a statistically significant 6 of the volatility in real stock returns for many european countries but not for the u s increased volatility of oil prices significantly depresses real stock returns the contribution of oil price shocks to variability in real stock returns in the u s and most other countries is greater than that of interest rate an increase in real oil price is associated with a significant increase in the short term interest rate in the u s and eight out of 13 european countries within one or two months counter to findings for the u s and for norway there is little evidence of asymmetric effects on real stock returns of positive and negative oil price shocks for oil importing european countries

what happened to the oil price macroeconomy relationship abstract strong evidence is found that oil prices no longer granger cause many u s macroeconomic indicator variables in data after 1973 a number of potential explanations are explored that sample stability issues are responsible that oil prices are now endogenous and that linear and symmetric specifications misrepresent the form of the oil price interaction none of these hypotheses are supported by the data the opec price increases do appear to have had significant impacts while the effects of the price declines of the 1980s are smaller and harder to characterize these results have potentially important implications for the large body of research which utilizes oil prices as an instrumental or explanatory variable

depreciation erodes the coase conjecture if a durable good monopolist produces at constant marginal costs and the good depreciates there exists a family of strong markov perfect equilibrium smpe one member of this family entails instantaneous production of the level of stock produced in a competitive equilibrium this is consistent with the coase conjecture other smpe in the family entail steady state production at a stock level lower than in the competitive equilibrium there may be a jump to these steady states or they may be approached asymptotically monopoly profits are positive in these equilibria and the coase conjecture fails

multiple equilibria in dynamic rational expectations models a critical review abstract multiple equilibria are a ubiquitous feature of dynamic rational expectations models researchers have been divided on the implications of this phenomenon some have viewed this as a reflection of reality and a possible explanation of a wide range of economic phenomena others have suggested various selection criteria for choosing one among the many equilibria this paper reviews the major selection criteria that have been proposed and through application to three well known models shows under what circumstances one might expect them to choose the same or different equilibria in addition this paper proposes a new criteria based on the limit of finite horizon equilibria and investigates its relation to the other criteria

impact of oil price shocks on output inflation and the real exchange rate evidence from selected asean countries this article analyses the impact of oil price shocks on real output inflation and the real exchange rate in thailand malaysia singapore the philippines and indonesia asean 5 using a structural var model the cointegration tests indicate that the macroeconomic variables of these countries are cointegrated and share common trends in the long run the impulse response functions reveal that oil price fluctuations do not impact the asean 5 economies in the long run and much of its effect is absorbed within five to six quarters the variance decomposition results further assert that with a few exceptions oil price shocks do not explain a significant variation in any of the variables under consideration we also identify a very unique pattern of response to oil price fluctuations between malaysia and singapore and between the philippines and thailand the pairs exhibit a high degree of similarity in their responses they do not share any commonalities across the group

durable goods monopoly increasing marginal cost and depreciation this paper combines increasing marginal cost and depreciation in a continuous time model of a durable goods monopolist in contrast to the case of increasing marginal cost but no depreciation analysed by kahn and the case of depreciation with constant marginal cost analysed by bond and samuelson steady state output in this model is less than in the competitive case a turnpike result shows that choice of a long enough time horizon can make the equilibrium path of output in a finite horizon game arbitrarily close to the path of the infinite horizon game

durable goods monopoly with entry of new consumers this paper analyzes a model of a dynamic monopolist who produces at constant unit cost each period a new cohort of consumers enters the market each entering cohort is identical consumers within a cohort have different tastes for the good my main results are if players are sufficiently patient any positive average profit less than the maximum feasible level can be attained in a subgame perfect equilibrium in the subset of subgame perfect equilibria in which players use stationary strategies the seller cannot make sales at prices significantly greater than the lowest willingness to pay when period length goes to zero and the seller attains the maximum profit when commitment is feasible by charging the same static monopoly price in every period this paper analyzes a model of a dynamic monopolist who operates in a market in which there is a regular flow of new consumers the seller produces a durable good at constant unit cost each period a new cohort of consumers enters the market consumers wish to buy exactly one unit of the item but are willing to wait resales are not allowed each entering cohort is identical

durable good monopolies with rational expectations and replacement sales a monopoly producer of a durable good is examined under the previously uninvoked assumption that the good depreciates and hence that replacement sales must occur if a fixed stock of the good is to be maintained we find two ways in which the no depreciation result that the monopoly will always at least eventually produce a stock equal to that produced by a competitive market may not hold if the length of the trading period is nonzero the limiting stock produced by the firm will be lower than the competitive stock to ensure the profitability of future replacement sales if the firm is able to constrain its production capacity it may choose a constraint that always binds in the sense that it will be impossible for the firm to achieve a stock equal to the competitive stock

dynamic product diversity the goal of this paper is to study the frequency of new product introductions in monopoly markets where demand is subject to transitory saturation we focus on those types of goods for which consumers purchase at most one unit of each variety but repeat purchases in the same product category the model considers in nitely lived forward looking consumers and rms we show that the share of potential surplus that a monopolist is able to appropriate increases with the frequency of introduction of new products and the intensity of transitory saturation if the latter is su ciently strong then the rate of introduction of new products is higher than socially desirable excessive dynamic product diversity jel classi cation numbers l12 l13

large shareholders monitoring and ownership dynamics toward pure managerial firms abstract we study ownership dynamics when the manager and the large shareholder both risk neutral simultaneously choose effort and monitoring level respectively to serve their non congruent interests we show that there is a wedge between the valuation of shares by atomistic shareholders and the large shareholder s valuation at the markov perfect equilibrium the large shareholder divests her shares if the incongruence of their interests is mild divestment is drastic all her shares are sold immediately if their interests diverge sharply the divestment is gradual in order to prevent a sharp fall in share price in the limit the firm becomes purely managerial

oil and the macroeconomy when prices go up and down an extension of hamilton s results in an important paper hamilton 1983 demonstrated a strong correlation between oil price changes and gross national product growth in u s data however his study pertained to a period in which all the large oil price movements were upward and thus it left unanswered the question whether the correlation persists in periods of price decline moreover the price variable he used was somewhat distorted by price controls in the 1970s this note investigates whether hamilton s results continue to hold when the sample is extended to include the recent oil market collapse and the oil price variable is corrected for the effects of price controls particular attention is given to the possibility of asymmetric responses to oil price increases and decreases as suggested in the structural employment literature loungani 1986 davis 1987 hamilton 1988 like hamilton i based my investigation on the gnp equation in sims s 1 980b six variable quarterly vector autoregressive model

expectations learning and the changing relationship between oil prices and the macroeconomy this paper estimates a structural general equilibrium model to investigate the changing relationship between the oil price and macroeconomic variables the oil price through the role of oil in production and consumption affects aggregate demand and supply in the model the assumption of rational expectations is relaxed in favor of learning oil prices therefore affect the economy through an additional channel i e through their effect on the formation of agents beliefs the estimated learning dynamics indicates that economic agents perceptions about the effects of oil prices on the economy have changed over time oil prices were perceived to have large effects on output and inflation in the 1970s but only milder effects after the mid 1980s since expectations play a large role in the determination of output and inflation the effects of oil price increases on expectations can magnify the response of macroeconomic variables to oil price shocks in the estimated model in fact the implied responses of output and inflation to oil price shocks were much more pronounced in the 1970s than in 2008 therefore through the time variation in the impact of oil prices on beliefs the paper can successfully explain the observed weakening of the effects of oil price shocks on real activity and inflation