Mercoledì 9 Dicembre, alle ore 13,
presso l'Aula Fanfani al 5° piano del Dipartimento MEMOTEF
(Sapienza Università di Roma, Via del Castro Laurenziano 9, Roma),
si terrà il seminario:
"How superaddittive can a risk measure be?"
Speaker: Velaria Bignozzi (Sapienza University of Rome).
ABSTRACT
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Risk measures that are not subadditive may penalize the aggregation of
risk, by inducing portfolio requirements that are larger than those of
undiversified positions. This happens for instance for Value-at-Risk (VaR),
as well as convex shortfall risk measures. In this paper we characterize
the potential for superadditivity that any risk measure may exhibit,
considering both dependence uncertainty as well as the effect of portfolio
size.
It is shown that for the wide majority of risk measures of use or interest
this corresponds to calculating the smallest dominating coherent risk
measure (SDCRM). We show that this risk measure often exists and is
identified with the notion of extreme-aggregation risk measure introduced
in this paper. Explicit results are provided for the class of distortion
risk measures, where the SDCRM is again a distortion risk measure and for
the class of shortfall risk measures, where the SDCRM is given by an
expectile.
Tutti gli interessati sono invitati a partecipare.
Cordiali saluti,
Gabriele Stabile