Competitive markets with externalities

This paper presents a general model of a competitive market with consumption externalities, and establishes the existence of equilibrium in the model, under assumptions comparable to those in classical models. The model allows production and indivisible goods. Examples illustrate the generality and applicability of the results.Competitive equilibrium, externalities, distributional economies

Competitive Markets without Commitment

In the presence of a time-inconsistency problem with optimal agency contracts, we show that competitive markets implement allocations that Pareto dominate those achieved by a benevolent planner, they induce strictly more effort, and they sometimes make the commitment problem disappear entirely. In particular, we analyze a model with moral hazard and two-sided lack of commitment. After agents have chosen a hidden effort and the need to provide incentives has vanished, firms can modify their contracts and agents can switch firms. As long as the ex-post market outcome satisfies a weak notion of competitiveness and sufficiently separates individuals who choose different effort levels, the market allocation is Pareto superior to a social planner’s allocation. We construct a specific market game that naturally generates robust equilibria with these properties. In addition, we show that equilibrium contracts without commitment are identical to those with full commitment if the latter involve no cross-subsidization between individuals who choose different effort levels.Time-Inconsistency, Moral Hazard, Competitive Markets, Adverse Selection

Competitive Markets and Aggregate Information

This paper shows that a competitive market structure is identically efficient to a Walrasian rational expectations market when risk-averse agents base trades only on unbiased private signals. Because price reflects the complete set of market information, it is a sufficient statistic. The economic role of competing market makers is thus to aggregate information efficiently.Market Structure

COVID‐19 and competitive markets of securitisation

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Competitive Markets with Endogenous Health Risks

We study a general equilibrium model where agents’ preferences, productivity and labor endowments depend on their health status, and occupational choices affect individual health distributions. Efficiency typically requires agents of the same type to obtain different expected utilities if assigned to di¤erent occupations. Under mild assumptions, workers with riskier jobs must get higher expected utilities if health a¤ects production capabilities. The same holds if health affects preferences and health enhancing consumption activities are sufficiently effective, so that income and health are substitutes. The converse obtains when health a¤ects preferences, but health enhancing consumption activities are not very effective, and hence income and health are complements. Competitive equilibria are first-best if lottery contracts are enforceable, but typically not if only assets with deterministic payoffs are traded. Compensating wage differentials which equalize the utilities of workers in different jobs are incompatible with ex-ante efficiency. Finally, absent asymmetric information, there exist deterministic cross-jobs transfers leading to ex-ante efficiency.compensating wage differentials, competitive markets, individual health risks, Pareto efficiency

Competitive markets and “as if” methodology

Two results showing the limitations of the “as if” methodology are proved under relatively mild assumptions. In an interpretation of the results, a competitive market cannot simulate the outcome of a market M in which the single price assumption does not hold. In a second interpretation, the market M resulting from the aggregation of a finite number of competitive markets is not competitive. In both cases there is no ground to sustain the fiction that M operates as if it were competitive.“As if” methodology; Competitive market; Market aggregation; Market simulation; Price aggregation.

EXPLORING SUPPLY DYNAMICS IN COMPETITIVE MARKETS

Understanding the ebb and flow of competitive markets is essential for students pursuing a variety of undergraduate degrees. The objective of this study is to introduce users to interactions that occur in the supply side of competitive markets using a dynamic simulation model with curriculum materials.Marketing,

The Effects of Competition on Variation in the Quality and Cost of Medical Care

We estimate the effects of hospital competition on the level of and the variation in quality of care and hospital expenditures for elderly Medicare beneficiaries with heart attack. We compare competition's effects on more-severely ill patients, whom we assume value quality more highly, to the effects on less-severely ill, low-valuation patients. We find that low-valuation patients in less-competitive markets receive more intensive treatment than in more-competitive markets, but have statistically similar health outcomes. In contrast, high-valuation patients in less-competitive markets receive less intensive treatment than in more-competitive markets, and have significantly worse health outcomes. Since this competition-induced increase in variation in expenditures is, on net, expenditure-decreasing and outcome-beneficial, we conclude that it is welfare-enhancing. These findings are inconsistent with conventional models of vertical differentiation, although they can be accommodated by more recent models.

Non-competitive markets

Among all the paradigms in economic theory, the theoretical predictions of oligopoly were the first to be examined in the laboratory. In this chapter, instead of surveying all the experiments with few sellers, we adopt a narrower definition of the term “oligopoly”, and focus on the experiments that were directly inspired by the basic oligopolistic models of Cournot, Bertrand, Hotelling, Stackelberg, and some extensions. Most of the experiments we consider in this chapter have been run in the last three decades. This literature can be considered as a new wave of experimental works aiming at representing basic oligopolistic markets and testing their properties. The chapter is divided into independent sections referring to different parts of the oligopolistic theory, including both monopoly as well as a number of extensions of the basic models, which have been chosen with the aim of providing a representative list of the relevant experimental findings

Competitive market for multiple firms and economic crisis

The origin of economic crises is a key problem for economics. We present a model of long-run competitive markets to show that the multiplicity of behaviors in an economic system, over a long time scale, emerge as statistical regularities (perfectly competitive markets obey Bose-Einstein statistics and purely monopolistic-competitive markets obey Boltzmann statistics) and that how interaction among firms influences the evolutionary of competitive markets. It has been widely accepted that perfect competition is most efficient. Our study shows that the perfectly competitive system, as an extreme case of competitive markets, is most efficient but not stable, and gives rise to economic crises as society reaches full employment. In the economic crisis revealed by our model, many firms condense (collapse) into the lowest supply level (zero supply, namely bankruptcy status), in analogy to Bose-Einstein condensation. This curious phenomenon arises because perfect competition (homogeneous competitions) equals symmetric (indistinguishable) investment direction, a fact abhorred by nature. Therefore, we urge the promotion of monopolistic competition (heterogeneous competitions) rather than perfect competition. To provide early warning of economic crises, we introduce a resolving index of investment, which approaches zero in the run-up to an economic crisis. On the other hand, our model discloses, as a profound conclusion, that the technological level for a long-run social or economic system is proportional to the freedom (disorder) of this system; in other words, technology equals the entropy of system. As an application of this new concept, we give a possible answer to the Needham question: "Why was it that despite the immense achievements of traditional China it had been in Europe and not in China that the scientific and industrial revolutions occurred?"Comment: 17 pages; 3 figure