It is known that the VaR (Value at risk) doesn't fulfill subadditivity, i.e.
$VaR(X)+VaR(Y) \le VaR(X+Y)$
But for elliptical distributions subadditivity is true. Questions:
(1) Which distributions are elliptical? I guess its the (multi)normal and t-distributions...Are stable and hyperbolic distributions elliptical,too?
(2) Is subadditvity only fulfilled for elliptical distributions? Are there any other conditions (e.g. correlation) which have an impact on subadditivity of VaR?