Easy, You should learn some basic rules about HEDGING
& DIVERSIFICATION. On the one hand, if your lead asset needs a hedge, try
to look for an asset with a CORRELATION quite near to 1 or -1. On the other
hand, if you want to invest the same money in two or more assets or anymore
cash will be invested in assets different to your current portfolio standings,
try to look for an asset with a CORRELATION near to 0. Hence, volatilities
values by themselves are NOT CRUCIAL FIGURES.
A huge difference arising here are the shares
percentages or weights of each asset. While when hedging, the hedge ratio is
deployed and the position (either long or short) comes defined by the direction
of the related correlation value; such a scheme does not apply when you are
solved to diversify.
The latter situation demmands OPTIMIZATION or a
predefined total return/total risk ratio to find out the weights of each
element belonging to the ensemble. The position to be held comes defined by THE
RELATIVE STRENGHT INDEX.
In the real world you wil never find a couple of
assets with a perfect CORRELATION. But the indifference or neutral zone is
given by the following interval: ]-0.5;0.5[
Hopefully, this
example will explain COPULAS for a DIVERSIFICATION PROCESS.
An investor holds a portfolio labeled: Emerging Market
Index (EMI), the investment pool has solved to diversify by entering a short
position in a portfolio labeled: Technological Market Index (TMI) The Gaussian
Correlation between EMI & TMI = -0.0277737277896621. The probabilities for
both indexes are in the event of a success: EMI = 0.607216494845361 & TMI =
0.579381443298969. In the event of a default: EMI = 0.392783505154639 & TMI
= 0.420618556701031. The investment pool concluded with a 50/50 position in both
assets.
Copula value
for a succes of such an ensemble? Copula value for a default of such an
ensemble? Copula value for a succes of one portfolio and a default of the
remainig one?
First, lets start by
building the probability space:
(0.607216494845361*0.5 *0.579381443298969*0.5)
= A
( 0.392783505154639*0.5
*0.420618556701031*0.5) =B
( 0.607216494845361*0.5
*0.420618556701031*0.5) =C
( 0.392783505154639*0.5
*0.579381443298969*0.5) =D =0.25. The
logics here are a bit tricky since you have a short position, both values have
been calculated assuming a long postion in the couple.
For the first scenario
asked: C/0.25 =0.255406525666915
For the second question asked: D/0.25 =
0.227571474120523
For the last question: A+B/0.25 = 0.517022000212562
Finally, a few warnings. If by luck you are handling 2
assets with correlation = 0 or among the neutral zone; you have got 4 scenarios
with near equal chances to happen. But if you are hedging, and your 2 assets
have a correlation either equal to 1 or -1, you have to build 2 scenarios only
and 2 scenarios are feasable to happen!
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