Allocative and Informational Externalities in Auctions and Related Mechanisms

We study the effects of allocative and informational externalities in (multi-object) auctions and related mechanisms. Such externalities naturally arise in models that embed auctions in larger economic contexts. In particular, they appear when there is downstream interaction among bidders after the auction has closed. The endogeneity of valuations is the main driving force behind many new, specific phenomena with allocative externalities: even in complete information settings, traditional auction formats need not be efficient, and they may give rise to multiple equilibria and strategic non-participation. But, in the absence of informational externalities, welfare maximization can be achieved by Vickrey-Clarke- Groves mechanisms. Welfare-maximizing Bayes-Nash implementation is, however, impossible in multi-object settings with informational externalities, unless the allocation problem is separable across objects (e.g. there are no allocative externalities nor complementarities) or signals are one-dimensional. Moreover, implementation of any choice function via ex-post equilibrium is generically impossible with informational externalities and multidimensional types. A theory of information constraints with multidimensional signals is rather complex, but indispensable for our study

Social network externalities and price dispersion in online markets.

Ample empirical studies in the e-commerce literature have documented that the price dispersion in online markets is 1) as large as that in offline markets, 2) persistent across time, and 3) only partially explained by observed eretailers’ attributes. Buying on the internet market is risky to consumers. First of all, consumers and the products they purchase are separated in time. There is a delay in time between the time consumers pay and the time they receive the orders. Second, consumers and the products they purchase are separated in space. Consumers cannot physically touch or examine the products at the point of purchase. As such, online markets involve an adoption process based on the interaction of consumers’ experiences in the form of references, recommendations, word of mouth, etc. The social network externalities introduced by the interaction of consumer’s experiences reduces the risk of seller choice and allows some sellers to charge higher prices for even homogeneous products. This research aims to study online market price dispersion from the social network externalities perspective. Our model posits that consumers are risk averse and assess the risk of having a satisfactory transaction from a seller based on the two dimensions of the seller’s social network externalities: quantity externality (i.e., the size of the seller’s social network) and quality externality (i.e., the satisfactory transaction probability of the seller’s social network). We further investigate the moderating effect of product value for consumers on the impact of social network externality on online market price dispersion. Our model yields several important propositions which we empirically test using data sets collected from eBay. We found that 1) both quantity externality and quality externality of social network are salient in driving online price dispersion, and 2) the salience of social network externality is stronger for purchase behavior in higher value product categories.network externalities, price dispersion, online markets, word of mouth

Identification of Options and Policy Instruments for the Internalisation of External Costs of Electricity Generation. Dissemination of External Costs of Electricity Supply Making Electricity External Costs Known to Policy-Makers MAXIMA

In the present paper, after reviewing the results of the ExternE project and its follow-up stages in the estimation of the external costs of electricity production, we look at the policy instruments for the internalisation of such costs. Emphasis is given to subsidies, such as feed-in tariffs, competitive bidding processes and tradable green certificates to stimulate the use of renewables in the production of electricity. When policy-makers are asked to choose the instrument(s) to internalise the externalities in the electricity production, they have to find a solution that gives the best outcome in terms of efficiency, cost minimisation, impact on the job market, security of energy supply, equity of the instrument, technological innovation, certainty of the level of the internalisation, and feasibility. The choice of the instrument will require some trade-offs among these criteria. Conjoint choice analysis can help in investigating how stakeholders and policy makers trade off the criteria when choosing a policy for the internalisation of the externalities. In this paper we present the first results of a questionnaire that employs conjoint choice questions to find out how policy makers and stakeholders of the electricity market trade off some socio-economic aspects in the selection of the policy instruments for the internalisation of the externalities. The results of this first set of interviews will be useful for further research.Policy instruments, ExternE, External costs, Electricity, Conjoint choice analysis

Optimal complementary auctions

This paper considers the situation where two products are sold by the same seller, but to disjoint sets of potential buyers. Externalities may arise from each market outcome to the other. The paper examines the nature of the seller's optimal mechanism, and, for example in the case of positive externalities, it is shown that the allocation decision in either market depends on the highest types in both markets. The optimal mechanism can be implemented by an indirect mechanism that essentially charges winning bidders for the value of their externalities. The analysis is applied to the sale of public sector franchises including exploration and development rights for oil and gas tracts

The Pigouvian Tax Rule in the Presence of an Eco-Industry

Pollution abatement goods and services are now largely being delivered by a specialized “eco-industry.” This note reconsiders Pigouvian taxes in this context. We find that the optimal emission tax will depart from the marginal social cost of pollution according to the polluters’ and the environment firms’ relative market power.Pigouvian taxes, Environment industry

The Economics of Internet Markets

The internet has facilitated the creation of new markets characterized by large scale, increased customization, rapid innovation and the collection and use of detailed consumer and market data. I describe these changes and some of the economic theory that has been useful for thinking about online advertising markets, retail and business-to-business e-commerce, internet job matching and financial exchanges, and other internet platforms. I also discuss the empirical evidence on competition and consumer behavior in internet markets and some directions for future research.internet, market, innovation, advertising, retail, e-commerce, financial exchanges

Silent interests and all-pay auctions

If firms compete in all-pay auctions with complete information, silent shareholdings introduce asymmetric externalities into the all-pay auction framework. If the strongest firm owns a large share in the second strongest firm, this may make the strongest firm abstain from bidding. As a consequence, equilibrium profits of both firms may increase, but the prize may be allocated less efficiently. The reverse ownership structure is also likely to increase the profits of the firms involved in the ownership relationship but without these negative efficiency effects. -- Befinden sich Firmen im Wettkampf in All-Pay Auktionen unter vollständiger Information, so bringen stille Beteiligungen asymmetrische externe Effekte in den gesamten Auktionsrahmen. Hält die stärkste Firma einen großen Anteil an Aktien der zweitstärksten Firma, kann dies die stärkere Firma von weiteren Geboten abhalten. Als Folge vergrößern sich die Profite beider Firmen, sind jedoch weniger effizient verteilt. Das umgekehrte Eigentumsverhältnis hebt voraussichtlich die Gewinne der beteiligten Firmen an, jedoch ohne negative Effizienzauswirkungen.All-pay auctions,externalities,contests,silent minority shareholdings ¸ownership structure