Non-fungible Tokens - Exploring Suspicious Washtrader Communities in NFT Networks

Non-fungible Tokens (NFTs) have received increased attention since 2021. NFTs can be susceptible to fraudulent activities such as washtrading or trading of counterfeit digital assets. Such behaviors threaten the trust in this new trading space and for this reason, NFT skeptics are suspicious of the true values of highly priced digital assets. In this paper, we propose a two-step methodological approach to identify washtraded assets, and the suspicious communities of washtraders. Our approach uses bipartite graph characteristics to provide an efficient algorithm that does not require computationally intensive methods. We also identify the challenges in this stream of research and propose suggestions to address those challenges. Our method demonstrates practical applicability on real life networks of NFT transactions and opens doors for several future directions for investigating and exploring the communities of suspicious washtrading actors

Online Auctions

The economic literature on online auctions is rapidly growing because of the enormous amount of freely available field data. Moreover, numerous innovations in auction-design features on platforms such as eBay have created excellent research opportunities. In this article, we survey the theoretical, empirical, and experimental research on bidder strategies (including the timing of bids and winner's-curse effects) and seller strategies (including reserve-price policies and the use of buy-now options) in online auctions, as well as some of the literature dealing with online-auction design (including stopping rules and multi-object pricing rules).

Cyber-Shilling in Automobile Auctions: Evidence from a Field Experiment

We run a large field experiment with an online company specializing in selling used automobiles via ascending auctions. We manipulate experimentally the "price grid," or the possible amounts that bidders can bid above the current standing price. Using two diverse auction sites, one in New York and one in Texas, we find that buyer and seller behavior differs strikingly across the two sites. Specifically, in Texas we find peculiar patterns of bidding among a small but prominent group of buyers suggesting that they are "cyber-shills" working on behalf of sellers. These patterns do not appear in the New York auctions

Proving soundness of combinatorial Vickrey auctions and generating verified executable code

Using mechanised reasoning we prove that combinatorial Vickrey auctions are soundly specified in that they associate a unique outcome (allocation and transfers) to any valid input (bids). Having done so, we auto-generate verified executable code from the formally defined auction. This removes a source of error in implementing the auction design. We intend to use formal methods to verify new auction designs. Here, our contribution is to introduce and demonstrate the use of formal methods for auction verification in the familiar setting of a well-known auction

Debarment and collusion in procurement auctions

This article presents the first experiment exploring the impact of debarments – the exclusion of colluding bidders – on collusion in procurement auctions. We find that debarments reduce collusion and bids relative to a market with no sanction. The deterrent effect of debarments increases in the length of the punishment. However, shorter debarments reduce efficiency and increase the bids of non-debarred bidders. This suggests that debarments that are too lenient may trigger tacit collusion among the bidders who remain in the market, thereby facilitating the very behavior they aim to deter

Bidder Collusion and Antitrust Law: Refining the Analysis of Price Fixing to Account for the Special Features of Auction Markets

Courts and commentators have painstakingly analyzed antitrust policy toward horizontal price fixing, but surprisingly, one of the most common forms of price fixing--bidder collusion-has escaped the sustained attention of antitrust lawyers. We attribute this inattention to the mistaken belief that the economics of bidder collusion is essentially equivalent to the economics of price fixing in posted-price markets. However, there are significant differences regarding the economics of collusion in auction and procurement markets as compared to posted-price markets, and we derive antitrust policy recommendations that apply specifically to bidder collusion in this article

Shill Bidder’s Behavior in a Second-Price Online Auction

Shill bidding is a fraudulent in-auction strategy where a seller participates as a bidder in his own auctions. This is the first paper on shill bidding that is based on a data set which includes personal details. Along with bidding histories, I can prove that on the investigated platform 0.3% of all auctions were influence by obvious shill bidders. The majority of the proven shill bidders' behavior in this paper does not fulfill any of the shill bidder types' criteria discussed in the literature. I adopt two algorithms which aim to identify shill bidders based on public information. On average, these approaches assign a higher probability of being a shill bidder to the accounts of bidders who certainly shilled on auctions in my data set. However, a reliable identification of proven shill bidders and honest bidders is only possible to a limited extent