Levy-stable distributions revisited: Tail index > 2 does not exclude the Levy-stable regime

Authors
Citation
R. Weron, Levy-stable distributions revisited: Tail index > 2 does not exclude the Levy-stable regime, INT J MOD C, 12(2), 2001, pp. 209-223
Citations number
36
Categorie Soggetti
Physics
Journal title
INTERNATIONAL JOURNAL OF MODERN PHYSICS C
ISSN journal
01291831 → ACNP
Volume
12
Issue
2
Year of publication
2001
Pages
209 - 223
Database
ISI
SICI code
0129-1831(200102)12:2<209:LDRTI>>2.0.ZU;2-G
Abstract
Power-law tail behavior and the summation scheme of Levy-stable distributio ns is the basis for their frequent use as models when fat tails above a Gau ssian distribution are observed. However, recent studies suggest that finan cial asset returns exhibit tail exponents well above the Levy-stable regime (0 < alpha < 2). In this paper, we illustrate that widely used tail index estimates (log-log linear regression and Hill) can give exponents well abov e the asymptotic limit for alpha close to 2, resulting in overestimation of the tail exponent in finite samples. The reported value of the tail expone nt alpha around 3 may very well indicate a Levy-stable distribution with al pha approximate to 1.8.