rules out the need for social coordination about the anticipation of the crash
(this can be regarded as implicitly assumed). The representative agent has
a utility function of the form
U(c) = EP X βtu(ct) ,
t∈N+
where P is an arbitrary belief process, where β ∈ (0, 1) is a constant, and
where the function u is defined as
for some α > 0 (this parameter is the coefficient of risk-aversion of the agent).
We show in Appendix B that the asset structure is irrelevant to carry out
our simulations, provided that the agent is not constrained in borrowing in
equilibrium.
u(x) =
x1 -α - 1
1-α
Fix now any history st-1, let st → st-1 be the history following st-1 where
the crash is expected and let st ,→ st-1 be the other history following st-1 .
In Appendix B, we show that
RSt ≤ ∣4∙( wwst- )α (6)
β 1St wst-1
for every security j as before, and regardless of the asset structure provided
that the agent is not constraint in borrowing in equilibrium. In particular,
Inequality (6) shows that the upper-bound on equilibrium returns depends
only the parameters γ, δ, α and β . The following numerical simulations are
generated directly from this last inequality.
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