# Questions tagged [covariance-matrix]

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### How to incorporate "correlation neglect" in a M-V-Framework?

at the risk of boring you with another behavioral finance question, i found a bunch of papers on a phenomenon dubbed correlation neglect, where economic agents misperceive the correlation structure of ...
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### Calculate Exponentially-Weighted Covariance Matrix over Finite Window

I have an (n,m) array (specifically containing asset returns over n days for m assets). I'm ...
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### Portfolio optimization - Correlation risk stress testing - DCP

I have a script based on Python/CVXPY trying to define the portfolio with the maximum expected return, given some risk constraints. I would like to introduce a constraint that limits correlation risk. ...
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### N asset covariance matrix vs N-1 asset covariance matrix

so I have been using a M-V framework to form M-V efficient portfolios. I have noticed that every time I make my investment universe smaller the minimum variance frontier moves to the right. This ...
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### Variance covariance matrix for a portfolio of credit derivatives

If the var-covar matrix for equities takes the return on equity prices, what should the var-covar matrix for credit derivatives (like a CDS) take? Should it be the probability of default, since that ...
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### How to create three variable system + test the hypothesis that the VAR residuals from two variables' equations can be treated as "structural" errors

I am currently doing an econometrics assignment and am completely stumped on a question. I have screenshotted the question and pasted below. Both questions are to be answered on EViews; having looked ...
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### Sample Variance of Portfolio

Let $w$ denote a vector of portfolio weights, $r_i$ denote the $i$th return vector, $\Sigma$ denote the Covariance matrix of $r_i$ and let $\hat{\Sigma}$ denote the sample covariance matrix of $r_i$. ...
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### Why does Hierarchical Risk Parity ignore the clusters generated?

I am currently working through the Hierarchical Risk Parity algorithm (Lopez de Prado (2016) link ) and trying to understand each of the steps. I have completed the step of creating the clusters, and ...
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### Calculating covariance from three variances

I have been asked to look to refactor some code. There is a line shown below: $\text{implied covariance} = -\frac{(\text{var}_1 - \text{var}_2 - \text{var}_3)} {2}$, where $\text{var}_1$ is the ...
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### Estimate covariance matrix using prices

We generally estimate the covariance matrix of assets using their returns instead of prices. Why is that the case? I can think of two possible reasons and would appreciate comments/feedback regarding ...
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### Creating a Covariance Matrix

Lets say that you have the correlation of x,y and you have the standard deviations of x and y , how would you then find the covariance of x,y using the correlation of x,y and and the standard ...
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### Demonstration of the Schweinler-Wigner Orthogonalization procedure

Can anyone give me a practical demonstration of the Schweinler-Wigner Orthogonalization procedure? The steps of performing it or possibly a code snippet. The Schweinler-Wigner Orthogonalization ...
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### Is a more robust Covariance estimation possible?

I'm working on a mean-variance optimization problem, but instead of financial securities I'm choosing a 'portfolio' of N athletes. It is a 1-period optimization problem over one generic statistic ...
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### Volatility and weights of a portfolio whose value is negative

How do you calculate the one day standard deviation (in dollars) for a portfolio that is short \$30,000? How do you calculate the weightings to use? I already have the necessary covariance matrix.
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### Why annualizing sampled covariance matrix changes stock weight vector?

Question While optimizing a portfolio using 'Global Minimum Variance' (GMV) method, I found that annualizing a sampled covariance matrix makes a difference in stock weight vector. Q1. Why ...
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### Covariance matrix from GJR-GARCH?

I am implementing a AR(1)-GJR-GARCH(1,1) model to some asset returns, and I would need to have a covariance matrix but I struggle to see how I can compute one from the model I used? I know I can have ...
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### Widely accepted methods for coming up with the co-variance matrix of assets?

Question What are the widely accepted ways for coming up with co-variance matrix of assets after the Markowitz's modern portfolio theory? Question explained in more detail After Modern portfolio ...
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