Volume 86, Number 5, June 2009
Article Number 58003
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 15 June 2009
EPL, 86 (2009) 58003
DOI: 10.1209/0295-5075/86/58003

Self-organization for the stylized facts and finite-size effects in a financial-market model

V. Alfi1, 2, L. Pietronero2, 3 and A. Zaccaria2

1   Centro Studi e Ricerche “E. Fermi” - Compendio del Viminale, 00184-Rome, Italy, EU
2   Dipartimento di Fisica, Università di Roma “Sapienza” - Piazzale Aldo Moro 2, 00185-Rome, Italy, EU
3   Istituto dei Sistemi Complessi, CNR - via dei Taurini 19, 00185-Rome, Italy, EU

received 19 March 2009; accepted in final form 13 May 2009; published June 2009
published online 15 June 2009

We propose a mechanism to understand the phenomenon of self-organization of the stylized facts in financial markets. This question is addressed within a workable agent-based model which is particularly simple and mathematically well posed. A key element is the non-stationarity of the number of agents, that can enter or exit the market depending on the signal they perceive. This leads to a market dynamics which evolves spontaneously towards a regime with stylized facts. All situations without stylized facts are shown to be unstable. The stylized facts correspond to finite-size effects with respect to time and number of agents. These results have conceptual and practical implications that can be tested with suitable data.

89.65.Gh - Economics; econophysics, financial markets, business and management.
89.65.-s - Social and economic systems.
89.75.-k - Complex systems.

© EPLA 2009