High profit equilibria in directed search models

We consider a model of directed search where the sellers are allowed to post mechanisms with entry fees. Regardless of the number of buyers and sellers, the sellers are able to extract all the surplus of the buyers by introducing entry fees and making price schedules positively sloped in the number of buyers arriving to their shops. This is in contrast to results that are achieved for large markets under the assumption that sellers cannot influence the utility of any particular buyer (market utility assumption), in which case buyers obtain strictly positive rents. If there is a bound on the prices or on the entry fees that can be charged, then the equilibrium with full rent extraction does not exist any more, and the market utility assumption is restored for large markets.     

Sorting versus screening: Search frictions and competing mechanisms

In a market where sellers compete by posting trading mechanisms, we allow for a general search technology and show that its features crucially affect the equilibrium mechanism. Price posting prevails when meetings are rival, i.e., when a meeting by one buyer reduces another buyer's meeting probability. Under price posting buyers reveal their type by sorting ex-ante. Only if the meeting technology is sufficiently non-rival, price posting is not an equilibrium. Multiple buyer types then visit the same sellers who screen ex-post through auctions.     

Competitive-search equilibrium in monetary economies

Competitive search was recently introduced in monetary economics by Rocheteau and Wright [Money in search equilibrium, in competitive equilibrium, and in competitive search equilibrium, Econometrica 73 (2005) 175-203]. We extend their work by eliminating the restriction that the fees market makers charge to enter a submarket must be either non-negative or identical for buyers and sellers. Without this restriction, buyers pay a positive fee to enter the submarket they visit and nothing else when they meet a seller. Sellers are remunerated by the market makers from the entry fees collected from the buyers. This trading arrangement allows buyers to perfectly predict their expenses, so the opportunity cost of holding idle money balances is eliminated.     

CONTINGENT PRICES AND MONEY*

Price posting with directed search is a widely used trading mechanism. Coles and Eeckhout showed that if sellers are allowed to post prices contingent on realized demand instead of one price, then there is real market indeterminacy. In this article, we fit this contingent price‐posting protocol into a monetary economy. We show that, as long as holding money is costly, there exists a unique equilibrium rather than a continuum. In this equilibrium sellers post a low price for when the buyer is alone, a high price for when several buyers show up, and buyers randomize between sellers and money holdings.     

Evolutionary stability of bargaining and price posting: implications for formal and informal activities

In this paper we study the co-existence of two well known trading protocols, bargaining and price-posting. To do so we consider a frictional environment where buyers and sellers play price-posting and bargaining games infinitely many times. Sellers switch from one market to the other at a rate that is proportional to their payoff differentials. Given the different informational requirements associated with these two trading mechanisms, we examine their possible co-existence in the context of informal and formal markets. Other than having different trading protocols, we also consider other distinguishing features. We find a unique stable equilibrium where price-posting (formal markets) and bargaining (informal markets) co-exist. In a richer environment where both sellers and buyers can move across markets, we show that there exists a unique stable dynamic equilibrium where formal and informal activities also co-exist whenever sellers’ and buyers’ net costs of trading in the formal market have opposite signs.     

Option to wait in a search model

We consider a standard search model with buyers and sellers. Upon meeting the buyers make a take-it-or-leave-it offer, but the sellers have an option not to trade immediately but wait for more agents to appear. If more buyers come, there is excess demand, and the buyers engage in auction to get the good. Analogously, if more sellers come, the sellers engage in a Bertrand-type pricing game to sell the object. The option to wait restricts the price offer of the buyer; in an equilibrium in which trades are consummated without delay there is a unique price offer for the buyer.JEL Classification: C78, D44, D831     

SEARCH,ADVERSE SELECTION,AND MARKET CLEARING

We examine a dynamic decentralized trading model with infinitesimal sellers and buyers to investigate whether or not the market fails to clear in the limit of search friction vanishing. A seller, who has private information about product quality, and a buyer are matched to bargain over price. They form a long‐term relationship if they reach agreement. They return to the matching pool if they fail to agree or the existing relationship is dissolved. The market fails to clear if and only if the ratio of agents' patience over the dissolution rate exceeds a threshold.     

Confusopoly: competition and obfuscation in markets

This paper examines the effects of competition in experimental posted-offer markets where sellers can confuse buyers. I report two studies. In one, the sellers offering heterogeneous goods can obfuscate buyers by means of spurious product differentiation. In the other study, sellers offer identical goods and make their prices unnecessarily complex by having multi-part tariffs. I vary the level of competition by having treatments with two and three- sellers in both studies, and having an additional treatment with five-sellers in one study. The results show that average complexity created by a seller is not different for the treatments with two, three and five sellers. In addition, market prices are highest and buyer surplus is lowest when there are two sellers in a market.     

Convergence to perfect competition of a dynamic matching and bargaining market with two-sided incomplete information and exogenous exit rate

Consider a decentralized, dynamic market with an infinite horizon and incomplete information in which buyers and sellers' values for the traded good are private and independently drawn. Time is discrete, each period has length δ, and each unit of time a large number of new buyers and sellers enter the market. Within a period each buyer is matched with a seller and each seller is matched with zero, one, or more buyers. Every seller runs a first price auction with a reservation price and, if trade occurs, the seller and winning buyer exit with their realized utility. Traders who fail to trade either continue in the market to be rematched or exit at an exogenous rate. We show that in all steady state, perfect Bayesian equilibria, as δ approaches zero, equilibrium prices converge to the Walrasian price and realized allocations converge to the competitive allocation.     

Trading networks with price-setting agents

In a wide range of markets, individual buyers and sellers trade through intermediaries, who determine prices via strategic considerations. Typically, not all buyers and sellers have access to the same intermediaries, and they trade at correspondingly different prices that reflect their relative amounts of power in the market. We model this phenomenon using a game in which buyers, sellers, and traders engage in trade on a graph that represents the access each buyer and seller has to the traders. We show that the resulting game always has a subgame perfect Nash equilibrium, and that all equilibria lead to an efficient allocation of goods. Finally, we analyze trader profits in terms of the graph structure — roughly, a trader can command a positive profit if and only if it has an “essential” connection in the network, thus providing a graph-theoretic basis for quantifying the amount of competition among traders.     

Buyer groups as strategic commitments

Buyer cooperatives, buyer alliances, and horizontal mergers are often perceived as attempts to increase buyer power. In contrast to prior research emphasizing group size, I show that even small buyer groups composed of buyers with heterogeneous preferences can increase price competition among rival sellers by committing to purchase exclusively from one seller. Without transfer payments, at least one buyer group exists for each pair of sellers and buyer groups membership is chosen to achieve indifference between the two sellers. With transfer payments, and just two sellers, the grand coalition is a coalition-proof subgame perfect equilibrium (CP-SPNE), though equilibria with arbitrarily many buyer groups also exist. With three sellers (and with more sellers when the distribution of buyers is symmetric), a CP-SPNE always exists, all coalition-proof equilibria are payoff equivalent and have at least one buyer group for each pair of firms, so the grand coalition is not an equilibrium.     

A MARKET WITH FRICTIONS IN THE MATCHING PROCESS: AN EXPERIMENTAL STUDY*

We construct a laboratory market in which there is a friction in the matching between buyers and sellers. Sellers simultaneously post prices and then buyers simultaneously choose a seller. If more than one buyer chooses the same seller, the seller's single unit is randomly sold to one of them. Our results show a broad consistency with theoretical predictions, although price dispersion exists and is slow to decay. Prices also exceed the equilibrium level when there are only two sellers, and buyers' purchase probabilities are insufficiently responsive to price differences when there are two sellers.     

DIRECTED SEARCH,COORDINATION FAILURE,AND SELLER PROFITS: AN EXPERIMENTAL COMPARISON OF POSTED PRICING WITH SINGLE AND MULTIPLE PRICES

We experimentally examine posted pricing and directed search. In one treatment, capacity‐constrained sellers post fixed prices, which buyers observe before choosing whom to visit. In the other, firms post both “single‐buyer” (applied when one buyer visits) and “multibuyer” (when multiple buyers visit) prices. We find, based on a 2 × 2 (two buyers and two sellers) market and a follow‐up experiment with 3 and 2 × 3 markets, that multibuyer prices can be lower than single‐buyer prices or prices in the one‐price treatment. Also, allowing the multibuyer price does not affect seller profits and increases market frictions.     

MEETINGS AND MECHANISMS

This article shows how meeting frictions affect equilibrium trading mechanisms and allocations in an environment where identical sellers post mechanisms to compete for buyers with ex ante heterogeneous private valuations. Multiple submarkets can emerge, each consisting of all sellers posting a particular mechanism and the buyers who visit those sellers. Under mild conditions, high-valuation buyers are all located in the same submarket, and low valuation buyers can be in: (i) the same submarket, (ii) a different submarket, and (iii) a mixture of (i) and (ii). The decentralized equilibrium is efficient when sellers can post auctions with reserve prices or entry fees.     

Trade mechanism selection in markets with frictions

We endogenize the trade mechanism in a search economy with many homogeneous sellers and many heterogeneous buyers of unobservable type. We study how heterogeneity and the traders' continuation values—which are endogenous—influence the sellers' choice of trade mechanism. Sellers trade off the probability of an immediate sale against the surplus expected from it, choosing whether to trade with everyone and how quickly. In equilibrium sellers may simply target one buyer type via non-negotiable offers (price posting), or may price discriminate (haggling). We also study when haggling generates trading delays. A price setting externality arises because of a strategic complementarity in the sellers' pricing choices.     

Sequential auctions with randomly arriving buyers

We analyze a dynamic market in which buyers compete in a sequence of private-value auctions for differentiated goods. New buyers and new objects may arrive at random times. Since objects are imperfect substitutes, buyers? values are not persistent. Instead, each buyer?s private value for a new object is a new independent draw from the same distribution.We consider the use of second-price auctions for selling these objects, and show that there exists a unique symmetric Markov equilibrium in this market. In equilibrium, buyers shade their bids down by their continuation value, which is the (endogenous) option value of participating in future auctions. We characterize this option value and show that it depends not only on the number of buyers currently present on the market and the distribution of their values, but also on anticipated market dynamics.     

Internet auctions with many traders

We study a multi-unit auction environment similar to eBay. Sellers, each with a single unit of a homogeneous good, set reserve prices at their own second-price auctions. Each buyer has private value for the good and wishes to acquire a single unit. Buyers can bid as often as they like and move between auctions. We characterize a perfect Bayesian equilibrium for this decentralized dynamic mechanism in which, conditional on reserve prices, an efficient set of trades occurs at a uniform price. In a large but finite market, the sellers set reserve prices equal to their true costs under a very mild distributional assumption, so ex post efficiency is achieved. Buyers’ strategies in this equilibrium are simple and do not depend on their beliefs about other buyers’ valuations, or the number of buyers and sellers.     

“递进”买方势力视角下两部收费制的规制机理研究--兼论政府反垄断部门应对策略

近年来,两部收费制策略引发的反垄断案件频发,下游买方势力的逐渐增强使得纵向控制规制问题变得更加错综复杂。以往研究对买方势力动态变化影响企业策略性决策以及弱化上游市场竞争的问题关注不足。基于此,构建由上游在位者、潜在进入者和下游零售商组成的纵向产业链模型,以下游零售商买方势力的递进变化为切入点,深度剖析两部收费制策略的内在规制机理。结果表明:当下游企业没有买方势力或者具有较弱的抗衡势力时,两部收费制策略从本质上并未弱化上游市场竞争。然而,一旦潜在进入者无法打破在位者建立的进入壁垒,在位者便会充分利用其市场支配地位实施转售价格维持、搭售等一系列纵向控制手段,进而弱化上游市场竞争,以期实现“一家独大”。当下游企业主导交易时,在满足一定条件下,通道费合约会产生排他效应,其弱化上游竞争的程度有限。因此,政府反垄断部门制定规制政策应充分考虑企业纵向控制和逆纵向控制行为。     

About market structure

I study an economy where sellers choose locations, and buyers choose which location to visit. All sellers in one location correspond to the Walrasian market while each seller in a separate location corresponds to the standard random matching model. Trades are consummated in auctions, and it turns out that the Walrasian market is not an equilibrium market structure. Rather, the sellers choose to distribute themselves in several locations endogenously creating the imperfectness of markets. I determine the number of sellers per location in equilibrium as a function of the ratio of buyers to sellers.     

The Demand for Information Services and the Market Structure

Uninformed buyers' demand for statistical screening between privately informed sellers is studied in a fixed price market. A single buyer will screen more extensively than would two or more buyers, since in the latter case buyers realize that sellers will be attracted to buyers with the most favorable screening policy (i.e., not to screen at all). This result is robust to some but not all types of modifications in the model. For instance, information quality differences in the sense of Blackwell will reinforce this effect. Furthermore, in equilibrium only the best information service will be used. Received April 17, 2001; revised version received January 24, 2002 Published online: November 11, 2002