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3
votes
2answers
127 views

Negative high frequency intraday volatility - Zhou estimator

To estimate high frequency tick data stock intraday volatility, I have read Robert Almgren's notes7.pdf http://www.cims.nyu.edu/~almgren/timeseries/notes7.pdf where he talks about the bias free ...
3
votes
2answers
78 views

Does heteroskedasticity of returns depend on the time frame?

Similarly to my last question, for which I obtained very interesting and useful answers, I would like to know if there has been any study regarding heteroskedasticity and time-frames of the returns. ...
6
votes
3answers
210 views

Variance swap replication and variance vega

Noob here. I've been trying to gain a better understanding of variance swaps and what better way than to replicate it with a portfolio of better understood instruments. I have read the GS 1999 ...
2
votes
1answer
78 views

out-of-sample variance using rolling window

I am currently working on the comparison of the constructed portfolios using out-of-sample variance criteria. I am going to use rolling window procedure for the comparison. First, I choose a window ...
1
vote
2answers
88 views

Modern portfolio theory in practice

I am wondering about the Markowitz theory of portfolio construction in practice. Hence, if one wants to know the efficient frontier, what variances can one use. The only method that I can think is the ...
5
votes
1answer
122 views

Variance replication using options

I would like to understand the intuition behind the following question: Why a certain weighted sum of prices of put and calls is equivalent to the implied variance of an underlying? A variance swap ...
0
votes
3answers
83 views

Variance calculation

How could I calculate variance when I have a snapshot of a portfolio that shows the following for each stock: Purchase Price, Close Price, Change in value, Change in percentage, Shares owned, ...
0
votes
2answers
139 views

Geometric Variance

If the arithmetic mean is: $ \frac { \Sigma (x_i) }{n}$ and the geometric mean is $ (\prod (1+x_i) ) ^{1/n}$ The arithmetic variance is $ \frac { \Sigma(x_i-\mu)^2 } {n} $ then what is the ...
0
votes
0answers
24 views

scale alpha forecasts to align with covariance matrix

I have a set of monthly alpha forecasts and my covariance matrix has been annualized. I would like to do a mean variance optimization with a linear tcost penalty term. How do I rescale my alpha ...
31
votes
7answers
2k views

Lévy alpha-stable distribution and modelling of stock prices.

Since Mandelbrot, Fama and others have performed seminal work on the topic, it has been suspected that stock price fluctuations can be more appropriately modeled using Lévy alpha-stable distrbutions ...
1
vote
1answer
55 views

Variance Swap volatility

In an article, it is mentioned that a parameter is "the variance swap volatility at time t". I know what a variance swap is but I don't know what they could mean by "variance swap volatility". ...
18
votes
7answers
24k views

What is the difference between volatility and variance?

How do volatility and variance differ in finance and what do both imply about the movement of an underlying?
0
votes
1answer
89 views

What are the parameters of the function PORTVAR in Matlab?

According to the Matlab help, Portvar will give the "Variance for portfolio of assets" by entering the returns of the Assets and the corresponding weight. However, it does not explain the parameters ...
2
votes
0answers
122 views

Why is this delta-hedging/P&L example on a variance swap call correct?

I'm looking into this article about var swaps: http://sbossu.com/docs/VarSwaps.pdf and not sure how to correctly interpret Exhibit 2.1.1. "In this example an option trader sold a 1-year call ...
1
vote
1answer
205 views

how to compute daily skewness of S&P daily return timeseries under no other more high - frequency time series?

As we all know , return time series marked features: fat tail or negative skewness and peakedness. For a similar problem of variance computation, we can compute variance by garch model and other ...
1
vote
1answer
197 views

Calculating Variance Explained from PCA Loadings

I have a return history for a universe of risky assets and I've run a principal component algorithm and obtained a loadings matrix (num_factors by num_assets) for the first 5 factors. I have a ...
4
votes
1answer
302 views

Calibrating Hull-White using volatility data

I would like to calibrate Hull-White model using volatility data.I am using [Park (2004)] paper as a reference. He suggests to minimize the following objective function: where the first term is ...
4
votes
0answers
529 views

Formula for the efficient portfolios (mean-variance optimisation)?

Consider the setting of mean-variance portfolio optimisation: $n$ assets with expected returns $\overline{r}_1,...,\overline{r}_n$ and standard deviations $\sigma_1,...\sigma_n$. For a certain fixed ...
1
vote
1answer
173 views

Basics about the scaling property of volatility

It is a usual practice to calculate realized volatility $\sigma$ using the square root of the usual variance estimator $\hat{{\sigma}²}$. This is done using the stock log returns (practitioners ...
1
vote
1answer
396 views

VaR Calculation - Covariance matrix is not positive semidefinite

This is a basic question. I have three assets, equally weighted, and all the mutual covariances are -1. Then, the covariance matrix looks like - ...
2
votes
0answers
963 views

How to calculate the conditional variance of a time series?

I am reading a paper where the term conditional variance is mentioned, but I am not really sure what is meant by this and how this can be calculated: Fig. 2 shows the conditional variances of the ...
5
votes
0answers
148 views

Distribution of hitting time of the integrated CIR process

If an increasing process $X_t$ has a known Laplace transform $\mathbb{E} e^{-s X_t} = m_t(s)$, define its hitting time $\tau$ to some level $B$ to be $$ \tau = \inf\{ u > 0 : X_u \geq B \}. $$ Can ...
1
vote
0answers
89 views

How to measure if variance is greater at a certain time of day?

I'm not very fluent in the quant vernacular, so perhaps the nature of my question will be better illustrated as a hypothesis. One market has closed and another market elsewhere on Spaceship Earth is ...
0
votes
0answers
75 views

Mean-variance minimizser

I am working on a project that involves pricing european call options in incomplete markets. Now I need to find a unique measure $Q^*$ such that $$Q^* = \min_{M_e} E_Q [V(T)-F(w)]^2 = \min_{u} E_Q ...
1
vote
0answers
531 views

portfolio optimization with a loop

I am attempting to minimize the variance of a 3 stock portfolio using optimization within a loop. What I have done is calculated the stock returns and cov matrix from dates 1980-01-01 to 1989-12-31 ...
1
vote
2answers
456 views

What is the instantaneous P&L of a Variance Swap?

What is the instantaneous P&L of a variance swap. Is it $(\sigma^{2}_{t}-\sigma^{2}_{implied})dt$?
7
votes
1answer
2k views

Conditional or unconditional volatility?

I am reading a paper (reference below) that states "The conditional volatility for each underlying security (or for a market index) can be estimated using the standard deviation of the stock’s ...
2
votes
1answer
192 views

How to calculate two-time scale variance?

I am having trouble understanding how to calculate two-time scale variance as I do not have a strong mathematical background. Suppose I want to calculate the TSRV at 5 min intervals. Do I calculate ...
3
votes
1answer
219 views

Why are there different estimators for stock volatility? (realized variance, RAV, etc)

I am very confused about why different volatility estimators (RV, RAV, BPV, etc) exist. If the goal is to find the best estimator for stock volatility, and volatility is latent, how do I know which ...
8
votes
2answers
700 views

Why do low standard deviation stocks tend to have superior future returns?

I've recently stumbled on something that really surprised me. These papers (1, 2) find that past standard deviation of returns is inversely related to future returns. That is, portfolio of low ...
2
votes
2answers
741 views

Should I use GARCH volatility or standard deviation in cross-sectional regression?

I want to do a cross-sectional study where the historical, medium-long run volatility of some return series (call it $R_t$) is included as a regressor. Which of the following two estimates of ...
1
vote
1answer
247 views

Minimum variance hedge with more than one asset

My portfolio comprises of 3 assets A,B,C that are correlated and the variance-covariance structure is known. At any given point in time, my position in Asset A say is given to me. I need to ...
2
votes
1answer
221 views

Combining covariances?

Consider an economy with assets with return processes $A$, $B$, $C$, $D$. Consider a weighted index with return process $I=aA + bB + cC + dD$ where $a,b,c,d$ are coefficients, and $a+b+c+d = 1$. ...
9
votes
5answers
9k views

Why would an investor trade a variance swap over a volatility swap?

Why would an investor trade a variance swap over a volatility swap? Is it simply related to the leverage involved in a Var (i.e. sigma-squared) or is there something else to it?
8
votes
1answer
261 views

Do weights from portfolio theory contain bias?

I want to experiment with some portfolio modelling and I was wondering if you guys could help me with something. If I try to estimate and implement the traditional two-fund portfolio consisting of one ...
3
votes
1answer
417 views

Linear regression and assets direction prediction

I have the following asset returns Y and the predictions for the same periods Y': Y = { 10, 200, -1000, -1, -7 } Y' = { 1, 2, -3, -4, -5 } The OLR R-squared for ...
4
votes
2answers
438 views

Choice of prior as a shrinkage target in portfolio construction?

There's various research showing how priors such as the minimum variance portfolio turn out to be a surprisingly effective shrinkage target in portfolio construction. The sell point of these priors ...
13
votes
4answers
771 views

Approximately what proportion of a stock’s volatility is explained by market movement?

Assume we decompose the daily (log) returns of a stock as beta times market movement plus an idiosyncratic part. If this is done ex-ante, what proportion of the variance is explained by the market ...
5
votes
1answer
183 views

How to scale option pricing components in regard to time

I am looking at closed-form options approximations, in particular the Bjerksund-Stensland model. I have run into a very basic question. How should I scale the input variables in regard to time? My ...
3
votes
2answers
840 views

Covariance for arbitrarily large portfolios

I am implementing a method in Java to calculate the variance, covariance, and value at risk for a portfolio, which should be flexible for use with any number of assets in a portfolio. I am struggling ...