Strategic Bidding for Multiple Units in Simultaneous and Sequential Auctions

A buyer in an electronic marketplace may be interested in buying a bundle of items, where any one item in the bundle may not be of particular interest. The emergence of online auctions allow such users to obtain bundles by bidding on different simultaneous or sequentially run auctions. Because the number of auctions and the number of combinations to form the bundles may be large, the bundle bidding problem becomes intractable and the user is likely to make sub-optimal decision given time constraints and information overload. We believe that an automated agent that takes user preferences and budgetary constraints and can strategically bid on behalf of a user can significantly enhance user profit and satisfaction. Our first step to developing such an agent is to consider bundles containing many units of a single item to be bought from auctions that sell only multiple units of one item type. We assume that users obtain goods over several days. Expectations of auctions and their outcome in the future allow the agent to bid strategically on currently open auctions. We present an expected utility based strategy to decide how many items to bid for in the current auctions, and the maximum price to bid for each item. We evaluate our proposed strategy in different configurations by varying the number of items sold per auction, number of concurrently running auctions, expected closing prices, etc. We simulate several multiple unit English auctions per day, over multiple days, where most of the bidders bid their true utilities drawn from a distribution. The strategic bidding agent has knowledge of this distribution and uses it to determine its bids. A strategic agent who looks farther ahead into the future produces larger returns when there are few strategic bidders. We also evaluate the effect of risk attitudes on the relative performance of the bidders.     

Ascending Combinatorial Auctions with Risk Averse Bidders

Ascending combinatorial auctions are being used in an increasing number of spectrum sales worldwide, as well as in other multi-item markets in procurement and logistics. Much research has focused on pricing and payment rules in such ascending auctions. However, recent game-theoretical research has shown that such auctions can even lead to inefficient perfect Bayesian equilibria with risk-neutral bidders. There is a fundamental free-rider problem without a simple solution, raising the question whether ascending combinatorial auctions can be expected to be efficient in the field. Risk aversion is arguably a significant driver of bidding behavior in high-stakes auctions. We analyze the impact of risk aversion on equilibrium bidding strategies and efficiency in a threshold problem with one global and several local bidders. Due to the underlying free-rider problem, the impact of risk-aversion on equilibrium bidding strategies of local bidders is not obvious. We characterize the necessary and sufficient conditions for the perfect Bayesian equilibria of the ascending auction mechanism to have the local bidders to drop at the reserve price. Interestingly, in spite of the free-riding opportunities of local bidders, risk-aversion reduces the scope of the non-bidding equilibrium. The results help explain the high efficiency of ascending combinatorial auctions observed in the lab.     

Auction Fever! How Time Pressure and Social Competition Affect Bidders’ Arousal and Bids in Retail Auctions

Auction sites on the Internet frequently put bidders under time pressure or highlight the social competition that is inherent to auctions. Both aspects are believed to elicit an exciting shopping experience, which may culminate in auction fever. In two laboratory experiments, we investigate the process of auction fever in retail auctions and demonstrate when and how auction fever affects bidding behavior. In contrast to previous studies, we employ physiological measurements as an objective and continuous assessment of bidders’ arousal in addition to a subjective assessment of bidders’ emotions through psychometric scales. Moreover, we explicitly study the interaction of time pressure and social competition on arousal and bids. We find that bidders’ arousal is increased in high time pressure auctions and that this leads to higher bids in ascending auctions—but only when bidders compete with human opponents. Thus, social competition is the actual driver underlying the auction fever phenomenon. Furthermore, we show that the “joy of winning” is significantly stronger than the “frustration of losing” in ascending auctions. Finally, we discuss the implications of our findings for the design of retail auctions.     

A Network Bidder Behavior Model in Online Auctions: A Case of Fine Art Auctions

The marketing literature provides a solid understanding of auctions regarding final sales prices and many aspects of the processes that unfold to result in those outcomes. This research complements those perspectives by first presenting a new bidder behavior model that shows the role of emergent network ties among bidders on the auction outcome. Dyadic ties are identified as the bid and counter-bid patterns of interactions between bidders that unfold throughout the duration of an auction. These structures are modeled using network analyses, which enables: (1) a richer understanding of detailed auction processes, both within auctions and across auctions of multiple lots, (2) a mapping of the processes to the forecast of prices and the trajectory toward final sales prices, (3) the clear and early identification of key bidders who are influential to the bidding action and who impact final auction sales prices, and (4) the results clearly show that the network exchange patterns are significant and contribute to an understanding of auction processes and outcomes above and beyond simple economic predictors such as the number of bids or bidders or the bidders’ economic status. We conclude by providing some managerial implications for online auction houses and bidders.     

Cryptographic protocols for Vickrey auctions

Although the sealed second-price or Vickrey auctions have some nice theoretical properties, they are fairly seldom utilized in practice. It has been suggested that they are vulnerable to bid-taker cheating and that the revelation of bids after the bidding makes the bidders reluctant to reveal their true valuations. We outline procedures based on modern mathematical cryptography that are instrumental in avoiding some of these difficulties and thereby will improve the properties of the Vickrey auctions.     

The impact of jump bidding in online auctions

This paper reports findings of two field studies, conducted on a local online auction website, that compare bidding strategies in charity and non-charity auctions, focusing on the extent of jump bidding at different stages of auctions. Results indicate that jump bidding is negatively correlated with bidder entry and positively associated with ending prices. These correlations are greatest during the beginning stage of auctions and are substantially larger for charity auctions than for non-charity auctions. Additionally, early-stage jump bidding occurred more often in charity auctions (consistent with bidders trying to drive up prices in charity auctions), ending-stage jump bidding was more frequent in non-charity auctions (possibly used strategically to win the auction). Further, frivolous products tended to sell at a higher proportion of retail value in charity auctions, providing a replication of the results of previous researchers but in a field setting.     

Bidder motives in cause-related auctions

We study cause-related auctions where a percentage of the dynamically determined purchase price of an item is donated to charity. Little is known about the effectiveness of such auctions. Bidders who value donations to charity have an incentive to bid more aggressively in such auctions. Regardless of whether they win or not, these bidders can significantly affect prices. The purpose of this paper is to study bidders' willingness to pay a premium in charity auctions and the drivers that affect the charity premium. We use a carefully designed field experiment involving simultaneous pairs of auctions that are identical in all respects but percentage of the proceeds donated to charity. This design gives us the ability to look at bidder choice among auctions based on charitable considerations. We use a mixture model approach to allow for different types of individual preferences. We find that individuals fall into three segments: two altruistic segments and a selfish segment. The altruistic segments, which drive up the charity premium, can be classified as warm glow bidders who derive pleasure from the act of giving and other-regarding bidders who give for selfless reasons. Results show that the difference in donation percentages is the major factor influencing the charitable premium. However, bidders differ considerably in their responses to donation percentages. While other-regarding bidders tend to seek auctions where a greater percentage of revenue is donated to charity, warm glow bidders only contribute when the charity premium is sufficiently low. Thus, managers should focus their marketing efforts on appealing to these different segments, depending on the percentage donated to charity.     

Economics, Psychology, and Social Dynamics of Consumer Bidding in Auctions

With increasing numbers of consumers in auction marketplaces, we highlight some recent approaches that bring additional economic, social, and psychological factors to bear on existing economic theory to better understand and explain consumers' behavior in auctions. We also highlight specific research streams that could contribute towards enriching existing economic models of bidding behavior in emerging market mechanisms. This paper is based on the special session at the 6th Triennial Invitational Choice Symposium, University of Colorado Boulder, June 2004 (co-chaired by the first two authors).     

Bid-Elicitation Interfaces and Bidding Behavior in Retail Interactive Pricing

Advances in information technology have led to a substantial increase in the use of interactive pricing mechanisms, where buyers (i.e., consumers) and sellers (i.e., retailers) enter a formal computer-mediated price-negotiation process during which consumers submit bids for a specific product. This article examines how the interface used for bid elicitation affects bidding behavior and, ultimately, retailer profit. Our focus is on one key aspect of the bid-elicitation interface – how retailers require bidders to articulate their bids. Evidence from four experiments involving economically consequential bids demonstrates that the candidate bid amounts specified by the retailer have a strong influence on bidding behavior, and consequently also on retailer profit. In particular, the level of candidate bid amounts has a positive effect on actual bid amounts, whereas it has a negative impact on the likelihood that a consumer will actually submit a bid. Critically, we show that the former effect can more than offset the latter to cause an increase in retailer profit. We propose and find support for two distinct pathways driving this phenomenon – the candidate bid amounts (1) influence bidders’ valuations of the offered product and (2) shape bidders’ beliefs about what bid amounts will be successful. Our results highlight the importance of the design of user interfaces for interactive pricing, demonstrating that even seemingly innocuous aspects of interfaces can have a dramatic impact on bidding behavior and retailer profit.     

Auctioning countermeasures in the WTO

We offer a first formal analysis of auctioning retaliation rights within the WTO. We show that the auctions exhibit externalities among bidders, and we characterize equilibrium bidder behavior under alternative auction formats. If the violating country is prevented from bidding to retire the right of retaliation against it, then the possibility of “auction failure” arises, whereby no bids are made despite positive valuation by bidders. If the violating country is instead permitted to bid, then auction failure is precluded, and indeed the right of retaliation is always retired. We evaluate these different auction formats from normative (revenue, compliance, efficiency) standpoints.     

Effect of Buyer and Seller Experience on Buy It Now Pricing

ABSTRACT

Although auctions have been around for centuries, online auctions are still a relatively new phenomenon. This paper examines the phenomenon of online auctions, specifically on a pricing option known as “Buy It Now.” With this option, a buyer can purchase merchandise immediately at a stated price and truncate the auction process. Auction items sold with a Buy It Now price tend to be at a higher price than the high bid price for an identical item sold through an ascending-bid auction. In addition, Buy It Now prices tend to attract risk averse bidders while high bidders of ascending-bid auctions tend to be less risk averse or risk neutral bidders. On the other hand, we found more experienced sellers sell their items with a Buy It Now price while less experienced sellers sell their items through an ascending-bid process. Thus, experience and risk are factors in choosing a Buy It Now price for the seller and buyer.     

On the Demand Elasticity of Initial Public Offerings: An Analysis of Discriminatory Auctions

We analyze 52 Taiwanese IPOs that were introduced through discriminatory auctions (you pay what you bid) between December 1995 and October 1998. The evidence suggests that the elasticity of demand for IPOs in Taiwan through discriminatory auctions is relatively flat. The elasticity is significantly negatively correlated with bidders’heterogeneity, which is consistent with the investor heterogeneity hypothesis. We also find that the average winning bidders earn a significant average abnormal return of 7.83% in the post–IPO market. The post–IPO market abnormal return is positively correlated with the demand elasticity, the idiosyncratic risk of stock returns and the institutional participation rate, and is negatively correlated with the auction clearing price, which is consistent with theory. Finally, there is evidence that informed investors have an incentive to shade their demand for IPOs to avoid the winner’scurse. The most aggressive bidders (the top 5% of the winning bidders) on average incur a small loss of 1.64% (not significant) in the market–adjusted initial returns.     

Procurement bidding with restrictions

In many procurement situations with simultaneously offered projects, firms face participation restrictions and can bid only on a subset of the projects. This phenomenon is prevalent in a variety of observed situations such as bidding for private label supplies, business to business procurement or government projects. We show that for the case of n bidding firms where each is restricted to bid on a subset of the offered projects, there exists a symmetric equilibrium in which each bidder has a positive expected equilibrium profit. Prices are bounded away from marginal costs even if all the bidders are homogenous. This results from the fact that there is a positive probability that each firm will find itself in the position of being the sole bidder on a project. While the equilibrium probability of bidding on a project increases with its value, it is interesting to note that the bidding probability on the projects approaches an equiprobable one as the number of bidding firms increases. We find that the equilibrium profits decrease as firms are able to bid on more of the available projects. In contrast, bidder commitment to bid on specific projects increases the equilibrium profits of all firms. We also examine the effect of heterogeneity on equilibrium profits. Greater heterogeneity in the project valuations leads to lower firm profits. On the other hand, heterogeneity among bidders in terms of the number of projects that they are constrained to bid on leads to greater profits for the firms that can bid on more projects (regardless of the mix of the firms in the industry.) Finally, we analyze the effect of uncertainty in project valuations and show greater uncertainty in project valuations (as represented by a mean preserving spread) decreases the equilibrium profits. We conclude with an empirical analysis of bidding behavior that tests the predictions of the theory. We find that the probability of bidding on a particular project is increasing in its value, decreasing in the other projects values and decreasing in the number of bidding subjects. Furthermore, the value of the bids on a project increase with its valuation and decrease with the total number of bidders.

The effect of experience on Internet auction bidding dynamics

On the basis of the bidding history of a panel of new eBay bidders, we examine the impact of different types of experiences on bidding behavior evolution. Accounting for unobserved bidder heterogeneity, the results indicate that losing experiences make the bidders’ bidding behavior evolve toward the normative predictions of auction theory, in that they submit fewer bids and bid later. Winning experiences, however, do not have such an effect. Moreover, the experience effect pertains to the bidder’s entire previous bidding experience regardless of product categories. We also assess the potential bias introduced by using feedback ratings (compared with actual participation) as experience measures.

(Un)expected Bidder Behavior in Spectrum Auctions: About Inconsistent Bidding and Its Impact on Efficiency in the Combinatorial Clock Auction

The combinatorial clock auction is a two-stage auction format, which has been used to sell spectrum licenses worldwide in the recent years. It draws on a number of elegant ideas inspired by economic theory. A revealed preference activity rule should provide incentives to bid straightforward, i.e., consistent with the bidders’ valuations on a payoff-maximizing package, in each round of the clock phase. A second-price rule should set incentives to bid truthfully in both phases. If bidders respond to these incentives and bid straightforward in the clock phase and truthful in the second sealed-bid stage, then the auction is fully efficient. Unfortunately, bidders might neither bid straightforward in the clock phase nor truthful on all packages in the second sealed-bid stage due to strategic reasons or practical limitations. We introduce metrics based on Afriat’s Efficiency Index to analyze straightforward bidding and report on empirical data from the lab and from the field in the British 4G auction in 2013 and the Canadian 700 MHz auction in 2014, where the bids were made public. The data provides evidence that bidders deviate significantly from straightforward bidding in the clock phase, which can restrict the bids they can submit in the supplementary phase. We show that such restrictions can have a significant negative impact on efficiency and revenue.     

Empirical Testing of the Reference-Price Effect of Buy-Now Prices in Internet Auctions

Retailers selling items through Internet auctions frequently use buy-now prices (BNPs), which allow the immediate selling of an item to consumers at a fixed price. Previous research has proposed several theories of the usage of BNPs by bidders. We study the usage of BNPs from a seller's point of view. We propose that a retailer may use BNPs as external reference prices, influencing bidders’ valuations in Internet auctions. We focus on the effect of BNPs on bidders’ willingness to pay (WTP) and study under what conditions a BNP can be effectively used as an external reference price. Results of two empirical studies clearly indicate that BNPs have a reference-price effect. In addition, we find that this effect is moderated by (1) the difficulty of value assessment and (2) product value.     

From Fatwallet to eBay: An investigation of online deal-forums and sales promotions

Sales promotions are an important part of retail advertising strategy. Traditionally, research on sales promotions has generally assumed that the buyers are end consumers who do not engage in reselling, in large part due to high transaction costs. However, the recent Internet related technologies have dramatically lowered the cost of transferring goods between consumers, leading to relative ease of reselling activity amongst individual consumers. Little is known about the impact of this phenomenon on retailer's sales promotion strategy. In this research we investigate the reselling activity in online auctions for products that active deal seekers can obtain at deeply discounted prices from retailers. We further investigate the role of deal-forums in the resale process. Data is collected from an online deal-forum (http://www.fatwallet.com/) and eBay to test various reselling-related hypotheses. The results show that there is a significant abnormal increase in the number of newly posted auctions of a product after the deal information of this product is posted on deal-forum website. We also find that there is a significant price incentive for individuals to resell. The implications for sales promotion research and practice are discussed.     

Maximizing earnings and price fairness perceptions in online consumer-to-consumer auctions

We examine the effects of starting bids on seller earnings in online consumer-to-consumer auctions. As starting bids increase, and the number of bidders increase, seller earnings increase. Both the affiliated private value model and a reference price explanation explain seller earnings. Bidder price fairness perceptions are also evaluated and, higher starting bids positively impact price fairness perceptions for winning bidders but have an adverse effect on losing bidders. In total, these findings suggest that sellers receive greater earnings as well as no adverse price fairness perceptions from winning bidders by setting starting bids higher.     

Vettes and lemons on eBay

This paper empirically tests whether there are asymmetric information problems in the market for used Chevrolet Corvettes sold on eBay. The first test is based on a result from Akerlof (Quarterly Journal of Economics, 1970). If there is asymmetric information in the used market, bidders should place a premium on a new Corvette, all else equal. The paper finds little systematic evidence of a new car premium. The second test is based on a result from Bajari and Hortacsu (Rand Journal of Economics 34(2):329–355, 2003). If there is asymmetric information, then bidders will prefer to bid late in the auction in order to conceal their private information from other bidders. The paper fails to find evidence of more late bidding on used Corvettes relative to new Corvettes. The third test is based on the idea that if there is asymmetric information then there may be a winner’s curse problem in these auctions. The paper fails to find evidence consistent with bidders avoiding the winner’s curse. The results are not consistent with asymmetric information problems in the market for used Corvettes sold on eBay. It is not clear however, whether this result generalizes to other cars sold on eBay or cars sold in the off-line market.     

An Empirical Analysis of Bidding Fees in Name-your-own-price Auctions

Interactive pricing mechanisms integrate customers into the price-setting process by letting them submit bids. Name-your-own-price auctions are such an interactive pricing mechanism, where buyers' bids denote the final price of a product or service in case they surpass a secret threshold price set by the seller. If buyers are given the flexibility to bid repeatedly, they might try to incrementally bid up to the threshold. In this case, charging fees for the option to place additional bids could generate extra revenue and reduce incremental bidding behavior. Based on an economic model of consumer bidding behavior in name-your-own-price auctions and two empirical studies, we analytically and empirically investigate the effects bidding fees have on buyers' bidding behavior. Moreover, we analyze the impact of bidding fees on seller revenue and profit based on our empirical results.