# Tag Info

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### Estimate Beta of CAPM from Implied Volatility?

Yes it is a better way. Just take a look to figure 3, from Buss and Vilkov (2012, RFS):

### What is the total correlation between assets in a portfolio?

I just want to add to vonjd's answer some info on the comparison of the 3 methods. This is too big for a comment so I'm posting as a separate answer but please upvote his answer, not mine. Do the ...
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### Which portfolio is more "diversified": the $\frac{1}{N}$, the MDP or the max decorrelation?

First of all, I am not sure what you mean by the ratio in your second point. However, I will try to give you a partial answer at least. There is a very comprehensive overview of these by EDHEC, page 4....

### What is the preferred GARCH method in practice?

I personally use the simple Garch(1,1) for volatility filtering in the risk management area. In fact in most cases I don't even estimate the parameters, I stick 0.94 for mean reversion, 0.04 for the ...
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### What is the most stable, non-trivial dependence structure in finance?

It is hard to find a stable non-trivial dependence structure in financial data. Usually when such is found it is hard to rationalize. One of my favorite (although I am sure there are others) is the ...
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Let us consider a basket $B$ with components $S_1,\dots,S_n$ : $$B(t) = \sum_{i=1}^nw_iS_i(t)$$ At time $t$, each component has standard deviation $\sigma_i$, $i \in \{1,\dots,n\}$, and pairwise ...

### Estimate covariance matrix using prices

If you assume that a financial asset price has a change that is a wiener process then you can view the future value of that asset as the initial value plus the sum of the independent daily changes (...
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### How to annualize the correlation matrix?

No, because correlation is a unitless quantity. As you use volatilities to do the scaling, the $\sqrt{252}$ factor should already be taken into account in them. If you take a correlation of 1 between ...

### Why do volatility and correlation increase in times of crisis?

Extra market volatility alone will cause correlations and stock volatilities to spike as you describe, even when overall market structure remains unchanged. There's a minor variation of the very ...
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### Correlation of a lognormal asset and a normal asset

Let $(X_t)_{t\geq 0}$ denote a Geometric Brownian Motion $$\frac{dX_t}{X_t} = \mu_X dt + \sigma_X dW^X_t,\ \ \ X(0) = X_0$$ such that $X_t$ is lognormally distributed $\forall t > 0$  X_t = X_0 ...
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### Creating a Covariance Matrix

here is how to get covariance matrix from correlations:
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### Simulating covariance matrices with nonzero correlation

What does 'simulate a covariance matrix' mean? If the question means, generate an arbitrary correlation matrix for 1000 stocks, then we can choose any symmetric matrix with all 1s down the diagonal, ...

### Why isn't it appropriate to use correlation between prices in a pairs trade strategy?

You could, and it doesn't hurt for you to test this yourself. Some of my best work has come from drawing the opposite conclusion to conventional wisdom or stylized "facts" in publications. That said, ...
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### Correlation between brownian motions and Cholesky decomposition

I assume, the first equation is about creating 2 correlated standard normal random variables. Then $X_1 = Z_1$ and $X_2 = \rho Z_1 + \sqrt{1- \rho^2}Z_2$ are correlated with correlation $\rho$. One ...
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### Information Coefficient (IC) Formulae Differences

Paraphrasing some quote: "they are different but same but still different" In reality the number of correct bets $N_c$ is the number of times the analyst was correct predicting the ...
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### Average Correlation

He is forced to use some tricks because Excel can only take average of a rectangular area, but he wants the avg of upper non-diagonal elements of the matrix only. So he subtracts $\frac{1}{n}$ (the ...

### Pearson correlation coefficient based on OHLC data

Given only OHLC information, with no timing information as when H and L occured in relation to one another, the covariance between any two assets is only defined for O and C since you know when these ...
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### Control for non-synchronous trading in correlations

I contacted one the authors of the original paper. He confirmed that the overlapping three day log returns are to be used on both stock and market returns.

### Why isn't it appropriate to use correlation between prices in a pairs trade strategy?

If you are correlating prices that would imply that you are sizing positions based on the number of shares in each position. This can result in a book that is very biased in terms of dollars invested....

### How to calculate implied correlation via observed market price (Margrabe option)

We know that $-1\le\rho_{imp}\le 1$ so perhaps the simplest approach is to try the possible values $\rho_{imp}=\{-1,-0.9,-0.8,\cdots,0.8,0.9,+1\}$, to calculate resulting $\sigma$ values, d± values, ...
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### Brownian Motions theorems

For the first part looks quite obvious, since independence implies that the covariance is zero and since the correlation is just the covariance divided by the product of the standard deviations, it ...

### Calculating Correlation of Two portfolios?

You may be over-thinking it. It is a straightforward calculation using matrices, as easy as turning the crank of a sausage-making machine. The standard deviation matrix is ...

### How to test ESG score as a factor against traditional factors

Preliminary/Warning: A correlation test is not an appropriate method for analyzing potential risk-factors! Let's (very precisely) recall, what a risk-factor is (see Bali/Engle/Murray (2016), p.173f.),...
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### Correlation Gold and SPX in BBG

I do not think that you were terribly wrong thinking that gold and SPX (or equity market in general) are negatively correlated. The reason behind this is that gold and stocks are in fact negatively ...
Your biggest problem is with computing the pairwise correlations of returns. Suppose for simplicity that you have 2 assets A and B. For asset A, you have closing prices for all 3 days $t_0$, $t_1$, ...