Value at Risk, a widely used risk measure of the risk of loss on a specific portfolio of financial assets.

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23
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2answers
6k views

What is the difference between the methods for calculating VaR?

There are three different commonly used Value at Risk (VaR) methods: Historical method Variance-Covariance Method Monte Carlo What is the difference between these approaches, and under what ...
17
votes
2answers
769 views

How are distributions for tail risk measures estimated in practice?

Let's say you want to calculate a VaR for a portfolio of 1000 stocks. You're really only interested in the left tail, so do you use the whole set of returns to estimate mean, variance, skew, and shape ...
13
votes
5answers
4k views

portfolio optimisation with VaR (or CVaR) constraints

I would like to optimize a portfolio allocation (maximizing the exposure or the expected return), but with VaR or CVaR contraints. (some parts of my portfolio cannot exceed a certain VaR) How can I ...
11
votes
1answer
321 views

What approaches are there for stress testing a portfolio?

Wikipedia lists three of them: Extreme event: hypothesize the portfolio's return given the recurrence of a historical event. Current positions and risk exposures are combined with the historical ...
9
votes
2answers
549 views

VaR for portfolio of funds

Let's assume we need to calculate a 1-day VaR for a portfolio of funds. Funds are traded, they can be bought and sold every day. We know exactly what the assets in each fund are. What is the right way ...
8
votes
3answers
997 views

How does Cornish-Fisher VaR (aka modified VaR) scale with time?

I am thinking about the time-scaling of Cornish-Fisher VaR (see e.g. page 130 here for the formula). It involves the skewness and the excess-kurtosis of returns. The formula is clear and well ...
7
votes
1answer
718 views

How to limit the nbr of cross-gamma calculations in a delta-gamma VaR calculation?

Many times, we want to calculate VaR using some parametric approach (delta-normal approximation for instance) when historical simulation or monte carlo are simply to slow. This is fine as long as only ...
7
votes
0answers
211 views

Extreme Value Theory possible for portfolios with options?

Say you have a portfolio with long exposure to a few linear assets (stock indices) and short exposure to a nonlinear asset (say call options on one of the linear assets). I am interested in ...
6
votes
2answers
601 views

How to minimize the difference between a parametric VaR and a MC-VaR with lognormal assumption?

Given that we want to find the Value at Risk for a portfolio of stocks only, there are two main methods to proceed. In the problem, we also assume that stocks follow a geometric Brownian motion. A ...
6
votes
1answer
492 views

Calculating VaR/CVaR on high frequency data and returns

As we converge on the minute time scale and below for our unit time interval, the return distributions tend to be leptokurtotic and more discretized (due to fixed values such as minimum price ...
6
votes
1answer
298 views

Which is a more appropriate choice of risk measurement in a utility function, CVaR or VaR?

What is the consensus on which risk measure to use in measuring portfolio risk? I am researching what is the best risk measure to use in a portfolio construction process for a long/short option-free ...
5
votes
3answers
117 views

Which lags or percentiles should be run in a batch when calculating Value-at-Risk?

Are there any "standard" VaR calculations run in a batch? For example, testing a VaR calculation with a lag of 1,2, 5 or 10 days over 2 years? Same question for the percentile, 1%, 2.5%, 5% etc.
5
votes
3answers
778 views

Expected Shortfall (CVaR) Backtesting

I am writing my thesis on VaR and ES risk measurements and have encountered some issues with how to best test the accuracy of ES estimates. My understanding of the topic is that backtesting ES ...
5
votes
0answers
1k views

VaR model Unconditional Coverage Tests: Is this extension of Kupiec POF test correct?

Background: Kupiec P. in 1995, published paper "Techniques for Verifying the Accuracy of Risk Management Models" on Journal of Derivatives, v3, P73-84, it's a Unconditional Coverage Tests designe for ...
4
votes
3answers
2k views

VaR implementation using quantlib?

I am thinking of writing a VaR framework for my existing system, using quantlib to do the bulk of the calculations. Despite several searches, I have not as yet come across a quantlib VaR ...
4
votes
1answer
450 views

Calculating portfolio VaR for (custom) leveraged products

I have been searching online for a few days regarding how to calculate portfolio VaR for a portfolio consisting of leveraged products - but so far, I have not been able to come up with anything ...
4
votes
2answers
722 views

VaR for corporate bonds

I am trying to create a simple risk calculation for the portfolio (ignoring correlations for the moment). I have some corporate bonds with limited daily price changes. Any one have ideas how I can get ...
4
votes
2answers
268 views

quantiative risk measure how they are implemented in R and their use

So far I have just theoretical knowledge of risk measure and never used them in application. Therefore I have some basic question how risk measures are used in reality and how they are implemented in ...
4
votes
3answers
139 views

Positive VaR when calculation on Total Return Indexes?

I recently saw a VaR calculation, and I was wondering whether that calculation made sense. Here the details: 1. Construction of a total return bond portfolio index. By total return I mean that the ...
4
votes
1answer
291 views

VaR mapping - Forward Foreign Currency Contract

I have a question about VaR mapping for FX forwards. Please bear with me while I outline the problem. Philippe Jorion's book discusses VaR mapping; a means to break down complex instruments into ...
3
votes
2answers
850 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 ...
3
votes
3answers
900 views

Do I need a copula to accurately estimate the VaR of a portfolio of risky assets?

I need to estimate the daily VaR of a portfolio of various exposures in $n$ risky assets (say equity futures). The simplest approach, I think, would be to just estimate VaR from a multivariate normal ...
3
votes
2answers
2k views

Is there a step-by-step guide for calculating portfolio VaR using monte carlo simulations

I am trying to determine a step-by-step algorithm for calculating a portfolio's VaR using monte carlo simulations. It seems to me that the literature for this is extraordinarily opaque for something ...
3
votes
1answer
162 views

How do I model risks for specific short-term short calls in a portfolio with limited data?

I'm trying to do some risk analysis on a portfolio of bonds, currency, stocks and short calls. The short calls expire in approximately 15-30 days and I've only got around 20 days of pricing data on ...
3
votes
2answers
313 views

central limit theorem and VAR

If I have a lot of data points and number of different dependent variables, can I use central limit theorem to assume data is multivariate normal and compute my VAR? Is this the appropriate use of ...
3
votes
2answers
280 views

Where can I find a list of VaR and CVaR formulas for continuous distributions?

Where can I find more VaR and CVaR formulas for continuous distributions? I collected a list here:
3
votes
2answers
535 views

Backtesting VaR model violation independence

I am interested in hearing about the practitioner state of the art for testing the time independence of a VaR model (i.e. that VaR violations are independent in time). There are a number of tests in ...
3
votes
2answers
165 views

How to Calculate a Monte Calo VaR estimation error

I'm performing a Monte Carlo to calculate value at risk (with a 3 dimension risk factor) Now, I would like to calculate the error of the estimation of the VaR with respect to the number of simulations ...
3
votes
1answer
107 views

How can I evaluate how poor a fit a parametric VaR result would be for a given holding?

I'm currently working on an application that, among other things, computes a one-day parametric VaR for security positions. I understand that the parametric method of computing VaR is a poor fit for ...
3
votes
0answers
70 views

Computing Value at Risk for portfolio in R

I know how to compute VaR with long positions using PerformanceAnalytics. What about a portfolio consisting in two equities A and B, 100 USD long positions in each, and 2 stock options for the same ...
2
votes
3answers
201 views

Ran multivariate linear regression, checked normal probability plot, residuals are not normal. What can I do?

One of the required assumptions for multiple linear regression is that residuals are normally distributed, correct? After running my regression, my normal probability plot is showing the typical ...
2
votes
2answers
65 views

Any package to run VAR-GARCH or VECM-GARCH models in R?

I need to estimate a multivariate VECM-GARCH (or simply VAR-GARCH) in R. Browsing on the internet, I did not find anything yet. Do you know if such kind of packages exists? Please, note that a BEKK ...
2
votes
3answers
111 views

comparing modified VaR to ordinary VaR

What inferences can one draw when given a modified VaR at x% confidence and an ordinary VaR at x% confidence level. If the two are equal one inference can be that returns are gaussian but that also ...
2
votes
1answer
247 views

Value at Risk from Delta of a single asset portfolio

I am trying to figure out the following, for me unfamiliar type of question: Given is a single asset portfolio: the Delta of the portfolio is 15, the value of the asset is 10 and the daily volatility ...
2
votes
1answer
676 views

How to calculate VaR/CVaR for private equity, hedge fund, and alternative investment portfolios?

What is the best method for calculating VaR/CVaR for private equity, hedge fund, and alternative investment portfolios? I have only historical monthly return for them.
2
votes
1answer
63 views

VaR calculation methods of options

I am a little bit confused about VaR in Options and I need a clarification for. I collected the following formulas, can you suggest what is the best formula and explain me why, please?
2
votes
2answers
176 views

How to compute the VaR for European Call, using the delta-normal method?

I have a European call option with current stock price $S_0$, strike $K$, risk-free rate $r$, volatility $\sigma$, and time to maturity $T$ years. I assume that the stock price at time $t$, which is ...
2
votes
1answer
72 views

Can you use a t-test on bootstrapped Value at Risk (VaR) figures?

I need to compare VaR before and after the recession. I have a series of market returns for a period before, and a series of market returns for the period immediately after. Both have been ...
2
votes
2answers
221 views

Is there a way to adjust R PerformanceAnalytics function VaR with EWMA or GARCH method?

Is there a way to upgrade R PerformanceAnalytics function VaR with more risk sensitive approaches like EWMA or GARCH? Or is there another R package which can handle the issue?
2
votes
1answer
110 views

Econometrics - Testing

If we have a time series of returns and two time series of indicators, how would we test the use of these indicators if they are autocorrelated or nonstationary (VAR Models dont produce significant ...
2
votes
1answer
40 views

VaR calculation accuracy/comparison/effectiveness through different R packages

My question is what would be the better( in terms of estimation accuracy) method of VaR calculation among below two:, also any small code snippet will be great as a starting point for me. 1st method: ...
2
votes
1answer
95 views

Calculating VaR with Monte Carlo simulation

I would like some help here :) I have a problem calculating VaR with the Monte Carlo Simulation. I have followed then next steps, is this a right way to calculate VaR or I need something more? ...
2
votes
0answers
96 views

Testing Statistical Significance of Various Portfolio Simulations

I'm trying to determine which of my portfolio simulations/backtests if any are good enough to put some money into. I outline an approach below and I'm interested in knowing: What problems are there ...
1
vote
1answer
403 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 - ...
1
vote
2answers
155 views

Reasoning behind multiple names for the equivalent risk measures AVaR/ETL/ES/CVaR

Doe's any one know the history behind, or background of the multiple naming conventions for the equivalent risk functions. Different quant authors prefer using different names, does any one know why? ...
1
vote
1answer
73 views

What would be an alternative if the VaR model is not acceptable?

Assume we have a VaR model wich says : the lost should not exceed X for more 3 days and we come up with more days where the lost exceeded X, what is usually done for the VaR model ? Do we switch to ...
1
vote
1answer
911 views

How to interpret/use VaR and Standard Deviation?

The parametric VaR is defined as follows: $$VaR=Z_a*Vol$$ Is this the best way to interpret how much risk is being taken on for a particular asset? How does one interpret volatility on its own if ...
1
vote
1answer
1k views

VaR for FX forwards

I am trying to figure out some of the commonly used approaches to deal with FX forwards (in a currency portfolio containing spots, forwards and swaps) that would allow me to calculate the one day VaR ...
1
vote
1answer
54 views

Why normalize only data for CDSs for PCA?

I'm reading a Credit Suisse Research Report on PCA. The report says that to preprocess the data, you should "Centre data (and normalize when considering CDS data)." Why would you only normalize ...
1
vote
1answer
298 views

Elicitability of risk measures

I read that CVaR (Conditional Value-at-Risk, also Expected Shortfall), satisfies coherence, but not Elicitability. On the other hand, VaR satisfies Elicitability, but not coherence. What is ...