% This script performs the butterfly-trading case study for the
% Entropy-Pooling approach by Attilio Meucci, as it appears in
% "A. Meucci - Fully Flexible Views: Theory and Practice -
% The Risk Magazine, October 2008, p 100-106"
% available at www.symmys.com > Research > Working Papers
% Code by A. Meucci, September 2008
% Last version available at www.symmys.com > Teaching > MATLAB
clear; close all; clc;
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% Load panel X of joint factors realizations and vector p of respective probabilities
% In real life, these are provided by the estimation process
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load 'FactorsDistribution.mat'; %
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% Load current prices, deltas and other analytics of the securities
% In real life, these are provided by data provider
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load 'ButterfliesAnalytics.mat'; %
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% Map factors scenarios into p&l scenarios at the investment horizon
% In real life with complex products, the pricing can be VERY costly
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PnL = HorizonPricing(Butterflies,X);
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% compute mean-risk efficient frontier based on prior market distribution
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Options.Quant=.95; % quantile level for CVaR
Options.NumPortf=30; % number of portfolios in efficient frontier
Options.FrontierSpan=[.1 .8]; % range of normalized exp.vals. spanned by efficient frontier
Options.DeltaNeutral=1; % 1 = portfolio is delta neutral, 0 = no constraint
Options.Budget=0; % initial capital
Options.Limit=10000; % limit to absolute value of each investment
[Exp,SDev,CVaR,w] = LongShortMeanCVaRFrontier(PnL,p,Butterflies,Options);
%PlotEfficientFrontier(Exp,CVaR,w)
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% process views (this is the core of the Entropy Pooling approach
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p_1 = ViewImpliedVol(X,p);
p_2 = ViewRealizedVol(X,p);
p_3 = ViewCurveSlope(X,p);
% assign confidence to the views and pool opinions
c=[.35 .2 .25 .2]; % sum of weights should be equal 1
p_=[p p_1 p_2 p_3]*c';
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% compute mean-risk efficient frontier based on posterior market distribution
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[Exp_,SDev_,CVaR_,w_] = LongShortMeanCVaRFrontier(PnL,p_,Butterflies,Options);
%PlotEfficientFrontier(Exp_,CVaR_,w_)
