Equilibrium in a market with intermediation is Walrasian

We show that a profit maximizing monopolistic intermediary may behave approximately like a Walrasian auctioneer by setting bid and ask prices nearly equal to Walrasian equilibrium prices. In our model agents choose to trade either through the intermediary or privately. Buyers (sellers) trading through the intermediary potentially trade immediately at the ask (bid) price, but sacrifice the spread as gains. A buyer or seller who trades privately shares all the gains to trade with this trading partner, but risks costly delay in finding a partner. We show that as the cost of delay vanishes, the equilibrium bid and ask prices converge to the Walrasian equilibrium prices. Received: 2 February 1996 / Accepted: 28 March 1997     

An equivalence theorem for a differential information economy

In a pure exchange economy with differential information and a finite set of traders, physical commodities and states of nature, we characterize the Walrasian expectations or Radner equilibria by using the veto power of the grand coalition. We prove that an allocation x is a Radner equilibrium allocation if and only if it is “privately non-dominated” by the grand coalition in every economy obtained by perturbing the original initial endowments in the direction of x. The first and second welfare theorems become particular cases of our main result. Since the deterministic Arrow–Debreu–McKenzie model is a special case of the differential information economy model we also provide a new characterization of the Walrasian equilibria.     

Consistent collusion-proofness and correlation in exchange economies

We present a feasible strategic market mechanism with finitely many agents whose Nash, semi-strong Nash and coalition-proof Nash equilibria fully implement the Walrasian equilibria. We define a strategic equilibrium concept, called correlated semi-strong equilibrium, and show that the Walrasian equilibria can be implemented by these equilibria, and also by the coalition-proof correlated equilibria of our mechanism. We show that these two concepts, suitably modified with transfers, fully implement the Pareto optimal allocations.     

Bankruptcy and optimality in a closed trading mass economy modelled as a non-cooperative game

In this paper we establish the existence of (a) an optimal bankruptcy rule which enables us to describe the Walrasian trading economy as a game with trade in fiat money; and (b) non- cooperative equilibrium points of this game which (in terms of prices and the final allocation yielded) include the competitive equilibrium points, and the accompanying money rate of interest (induced by borrowing at a central bank), when the bankruptcy rule is different from optimal.     

Convergence to competitive equilibria and elimination of no-trade (in a strategic market game with limit prices)

The strategic market games literature contains many results that predict Walrasian equilibria in the competitive limit. However, they usually come at the expense of ad hoc assumptions that rule out “pathological” no trade equilibria. This paper studies a strategic market game with limit prices. The set of Nash equilibrium allocations of this game converges to the set containing all competitive equilibria and no-trade, when players are replicated. Moreover, two rounds of iterated deletion of weakly dominated strategies eliminate the no-trade equilibria. Hence, replication paired with two rounds of iterated dominance gives a clean prediction of competitive equilibrium.     

Social Structure and Intermediation: Market‐making Strategies in International Exchange*

ABSTRACT Information gaps between markets create opportunities for international trade intermediaries to negotiate cross‐border exchanges. Faced with the prospect of eventually being eliminated from these exchanges, intermediaries must continually search for new opportunities to mediate international exchange. In this paper an original explanation is derived from the core principles of structural hole theory to explain how these market‐making firms operate in the tension found between the inevitable decay of existing exchange relationships and the uncertainty of finding replacement sources of income.     

The economics of markets and platforms

Advances in the study of both markets and platforms contribute to economics. Platforms are typically digital markets, although platforms can designate markets generally. So, the economics of markets and the economics of platforms are one and the same. Platforms show the critical role of intermediaries in endogenous price adjustment and market clearing. The platform model remedies problems with general equilibrium analysis by combining and extending the basic Walrasian and Marshalian market models. The analysis of platforms provides explanations for the bid–ask spread, including market power, search costs, matching costs, adverse selection, and moral hazard. The study of platforms demonstrates the importance of participation and coordination in the formation of markets. The discussion emphasizes that platforms have significant implications for the theory of the firm. The analysis further considers how platforms affect innovation and entrepreneurship.     

Can we identify Walrasian allocations?

Abstract. We consider a discrete time, pure exchange infinite horizon economy with consumers and consumption goods per period. Within the framework of decentralized mechanisms, we show that for any given consumption trade at any period of time, say at time one, the consumers will need in general an infinite dimensional (informational) space to identify such a trade as an intertemporal Walrasian one. However, we show a set of environments where the Walrasian trades at each period of time can be achieved as the equilibrium trades of a sequence of decentralized competitive mechanisms, using only both current prices and quantities to coordinate decisions. Received: 1 December 1999 / Accepted: 31 October 2000     

A dynamic equilibrium model of search, production, and exchange

We study a general equilibrium model where agents search for production and trading opportunities, that generalizes the existing literature by considering a large number of differentiated commodities and agents with idiosyncratic tastes. Thus, agents must choose nontrivial exchange as well as production strategies. We consider decreasing, constant, and increasing returns to scale in the matching technology, and characterize the circumstances under which there exist multiple steady state equilibria, or multiple dynamic equilibria for given initial conditions. We also characterize the existence of dynamic equilibria that are limit cycles. Equilibria are not generally optimal, and when multiple equilibria coexist they may be ranked. We analyze comparative statics and find that certain intuitive results do not necessarily hold without restrictions on the stochastic structure.     

Bilateral trade between India and Bangladesh: A general equilibrium approach

India and Bangladesh have pursued policies of trade liberalization since the early 1990s. However, owing to the differential speeds of opening up, Bangladesh's bilateral trade deficit with India widened substantially over the years. This aggravated the economic and the political tensions between the economies. It has been held that promotion of free trade between the two economies may enhance the trade and hence economic cooperation between them. Against this backdrop the present paper proposes a theoretical framework that provides a general equilibrium determination of the commodity pattern of trade and hence locates the comparative advantages of the economies. The empirical implementation of the model considers trade in 25 sectors comparable in the input–output tables of the economies. The study isolates the gains from free trade accruing to either economy. The paper also explores the pattern of bilateral trade when each economy produces goods by utilizing their own as well as the other country's technology. The gains from this trading arrangement are also isolated.     

Financial intermediation in an overlapping generations model with transaction costs

We analyze an overlapping generations economy where agents interact to share liquidity risk. We show that a pure exchange economy has excessive trade in equilibrium because agents interact to rebalance their portfolios. Intergenerational financial intermediaries reduce the number of interactions because agents only transact when they face liquidity needs. In the absence of asset risk, intermediaries match redemptions with deposits and dividends, and never sell assets. If the economy is subject to transaction costs, the intermediated economy can sustain higher stationary investment and welfare. We also find that dead weight transaction costs can increase welfare because it protects banks from interbank arbitrage and dampens the inherent cyclicality of market economies.     

Refinements and incentive efficiency in Walrasian models of insurance economies

The literature on Walrasian markets in large economies with adverse selection has used various equilibrium refinements, but has obtained no general incentive efficiency of equilibrium, namely when cross-subsidies are needed for efficiency. We show that the same refined equilibria may also be incentive inefficient even when general mechanisms that allow for such cross-subsidies are priced and can be traded. In the process, we also prove existence of some type of forward induction equilibria in this context.     

Growth and the dynamics of trade liberalization

This paper develops a model of ongoing trade liberalization as a self-enforcing equilibrium in a game between governments. Economic growth is a critical ingredient in successful trade liberalization. But differences in national growth rates have profound differences on the sustainable tariff equilibria of the game. If international technology spillovers are not concentrated in high-growth sectors, faster growing countries will be more protectionist, setting higher tariffs and liberalizing trade at a later date. But with spillovers more concentrated in high-growth sectors, faster-growing countries may be less protectionist. Differences in growth rates lead the process of trade liberalization to be far from reciprocal. A sustainable trade liberalization may actually involve one country pursuing a unilateral policy of free trade, even though its trading partner imposes tariffs against it.     

Dynamic gains from North American free trade in an equilibrium model of the current account

The benefits of economic integration in North America are explored by quantifying the gains that the two small open economies of the region can obtain from free trade in financial assets as a vehicle to smooth consumption. Numerical simulations of a stochastic intertemporal equilibrium model are used to estimate the effects of free financial asset trading on economic activity and welfare. The results suggest that in Mexico, where business cycles have been larger and access to world markets has been more limited, free asset trading would produce more benefits that in Canada, where the risk of business cycles is smaller.     

Investments and the holdup problem in a matching market

This paper studies the properties of the steady state equilibrium in a bilateral matching market with ex ante investments at the market entry stage. Investment incentives depend on search frictions because both parties in a match are partially locked-in when they bargain over the joint surplus from their sunk investments. The associated holdup problem is more important for the long side of the market. In the extreme case of perfectly substitutable investments only the agents on the short side make investments. When market frictions become negligible, the market equilibrium approaches the Walrasian outcome.     

ON THE SECOND STAGE OF THE CAMBRIDGE CAPITAL CONTROVERSY

The second stage of the Cambridge capital controversy concerns the neo‐Walrasian theory of value and distribution. Since production is not understood in this theory as employing factors of production but rather commodities, that is goods and services with date and place of delivery, some scholars maintained that it is not affected by the problems that emerged, during the first stage of the controversy, as regards the conception of capital as a factor of production and the rate of interest as the price for its use. The reply of the ‘neo‐Ricardians’ was based on two arguments. The first regarded the relevance of the new notions of equilibrium adopted in the neo‐Walrasian approach, with particular reference to temporary and Arrow–Debreu equilibria, and the second the possibility that the phenomena of re‐switching and reverse capital deepening, by affecting the working of the saving‐investment market, could cause equilibrium multiplicity and instability also in a neo‐Walrasian framework.     

Stability and efficiency from a Neo-Keynesian viewpoint

This paper raises once more the Keynesian challenge of the classical doctrine that an unguided market economy has a natural tendency towards optimal employment of resources. By means of a simple macromodel, we show that if quantity expectations are incorporated into the Walrasian model, then it is no longer generally true that the ‘invisible hand’ leads the economy to Walrasian equilibrium. Instead, it may lead the economy to a kind of Keynesian equilibrium in which the firms' sales expectations constitute a binding constraint on production. Moreover, while Pareto optimum is unstable and hence unattainable in our model, a ‘second-best’ optimum among stable equilibria exists and requires a public sector. Accordingly, a trade-off between efficiency and other policy aims occurs only at tax rates above the positive tax rate in optimum     

Equilibrium with coordination

The obvious equilibrium concepts in the simplest institutions for transferring ownership of commodities—bilateral exchange—are neither Nash equilibria nor cooperative equilibria. To study such equilibria as special cases of equilibria of a social system it is necessary to introduce coordination. Two or more agents coordinate their actions, if, when they consider an alternative to a state, they take as given—for agents with whom they coordinate—the alternative state. If there is no coordination we obtain Nash equilibrium as a special case. If there is complete coordination we obtain optimality as a special case. The main result is an existence theorem for a social system with coordination. This theorem is then applied to prove existence of exchange equilibria in an economy with bilateral exchange.     

Switching from complete to incomplete information

We construct an elementary mechanism [Dutta, B., Sen, A., Vohra, R., 1995. Nash implementation through elementary mechanisms in economic environments. Review of Economic Design 1, 173–203] that Nash implements the constrained Walrasian correspondence. We extend it to incomplete and non-exclusive information economies by enlarging the message space of agents. In addition, measurability restrictions on allocations with respect to prices proper to constrained rational expectations equilibria are imposed in the outcome function. We show that by imposing such restrictions, the mechanism Bayesian implements the constrained rational expectations equilibrium correspondence. This result shows game-theoretic connections between these two market equilibrium concepts. However, these connections are obtained at the price of strong restrictions on the behavior of agents.     

Matching, search and intermediation with two-sided heterogeneity

This paper analyzes the role played by intermediation in a decentralized market, where trade is carried out through bilateral bargaining, and where the bargaining outcome depends on the process of search for suitable trading partners. To this purpose, a monopolistic intermediary is embedded in a dynamic model of random-matching and two-sided search with heterogeneous agents. It is shown that intermediation might speed up the matching process and might induce separation of the agents’ types, thus enhancing sorting efficiency with respect to a pure search market, where sorting externalities cause multiplicity of equilibria to arise and determine inefficient matching outcomes. Nonetheless, intermediation might also introduce frictions that do not exist in a decentralized market operating in isolation, and this impairs efficiency.