TY  - JOUR
EP  - 499
ID  - eprints1115
UR  - http://dx.doi.org/10.1016/j.physa.2004.11.040
AV  - none
TI  - The scale-free topology of market investments
KW  - PACS:89.75.-k; 89.65.Gh; 02.50.Ey; 87.23.Ge. Keywords:     Complex networks; Econophysics; Wealth distribution;     Pareto's law
N2  - We propose a network description of large market investments, where both stocks and shareholders are represented as vertices connected by weighted links corresponding to shareholdings. In this framework, the in-degree (kin) and the sum of incoming link weights (v) of an investor correspond to the number of assets held (portfolio diversification) and to the invested wealth (portfolio volume), respectively. An empirical analysis of three different real markets reveals that the distributions of both kin and v display power-law tails with exponents ? and ?. Moreover, we find that kinscales as a power-law function of v with an exponent ?. Remarkably, despite the values of ?, ? and ? differ across the three markets, they are always governed by the scaling relation ?=(1-?)/(1-?). We show that these empirical findings can be reproduced by a recent model relating the emergence of scale-free networks to an underlying Paretian distribution of ?hidden? vertex properties.
SN  - 0378-4371
VL  - 350
IS  - 2-4
JF  - Physica A: Statistical Mechanics and its Applications
Y1  - 2005///
SP  - 491
A1  - Garlaschelli, Diego
A1  - Battiston, Stefano 
A1  - Castri, Maurizio
A1  - Servedio, Vito D. P.
A1  - Caldarelli, Guido
PB  - Elsevier
ER  -