SKM 2023 – wissenschaftliches Programm

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SOE: Fachverband Physik sozio-ökonomischer Systeme

SOE 21: Financial Markets and Risk Management I

SOE 21.1: Hauptvortrag

Freitag, 31. März 2023, 09:30–10:00, ZEU 260

Collective dynamics of online marketplaces — •Andrea Baronchelli — City, University of London

Online marketplaces play a crucial role in legal and illegal e-commerce, yet their empirical properties are not well understood due to a lack of large-scale data. In this talk, I will discuss the systemic aspect of the interaction between multiple platforms and zoom in on the properties of buyer-seller networks within a single platform.

First, I will focus on the resilience of the dark market ecosystem. I will analyze 24 instances of unexpected marketplace closure and show that coordinated user migration ensures overall resilience. Additionally, I will show that these marketplaces favor the emergence of decentralized trade networks, further enhancing systemic resilience.

Second, I will consider buyer-seller networks by analyzing 245 million transactions on one e-commerce platform and 28 dark web markets. Despite the differences between the marketplaces, I will show remarkable regularities in user behavior and propose a simple model to replicate the main empirical observations. The findings provide insights into the formation mechanisms of buyer-seller networks, and highlight the central role of buyer memory and preferential attachment mechanisms.

These results have implications for the understanding, design, and regulation of these platforms.

ElBahrawy, Abeer, et al. ``Collective dynamics of dark web marketplaces.'' Scientific reports 10.1 (2020): 1-8.

Nadini, Matthieu, et al. ``Emergence and structure of decentralised trade networks around dark web marketplaces." Scientific Reports 12.1 (2022): 1-9.

Bracci, Alberto, et al. ``Macroscopic properties of buyer-seller networks in online marketplaces.'' PNAS Nexus 1.4 (2022): pgac201.