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

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22
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2answers
4k 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
651 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 ...
12
votes
5answers
3k 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 ...
10
votes
1answer
295 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
523 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
504 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
621 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 ...
6
votes
2answers
519 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
416 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
261 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 ...
6
votes
0answers
144 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 ...
5
votes
3answers
107 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
0answers
864 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
2answers
474 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 ...
3
votes
2answers
740 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
641 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
3answers
1k 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 ...
3
votes
1answer
139 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
281 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
367 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
104 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
324 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 ...
3
votes
1answer
188 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 ...
3
votes
1answer
423 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 ...
3
votes
1answer
94 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 ...
2
votes
1answer
144 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
412 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.
1
vote
1answer
299 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
145 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
49 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
527 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
437 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
844 views

What does this formula (to derive annualized volatility from VaR) mean?

I'm faced with the formula shown in the image below, which I just don't understand, in part because I've no grounding in stats, and in part because I don't even understand the notation: What's ...
1
vote
0answers
39 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 ...
1
vote
1answer
98 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 ...
1
vote
1answer
72 views

Understanding the VaR example on wikipedia

In the wikipedia page on VaR The example says: ...
1
vote
0answers
128 views

Fixed Income Var calculation

I'm trying to calculate var for a portfolio of fixed income securities. I initially want to just calculate undiversified VaR for each instrument. I'm doing the following for each instrument Take ...
1
vote
0answers
238 views

VaR backtesting with overlapping time intervals

Of course the issue here is dependence: can it be removed or accounted for (in independence tests too, which of course would be troublesome)? There's a lot of literature on regression in this setting, ...
0
votes
2answers
144 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 ...
0
votes
1answer
89 views

Difference between VaR and credit VaR?

Quick question: is there a difference between credit VaR and VaR or are they the same thing?
0
votes
1answer
75 views

How to backtest the VaR model?

I have a sorted historical P&L vector of 250 days and say, I want to calculate the 90% VaR on this distribution. I will look for the 225 element (90% * 250 = 225) and this will be my Value at ...
0
votes
0answers
48 views

Correlating random numbers seems to skew the data

First off, apologies for the cross-post from mathematics, but I found this site later and think it would be a better fit for the question (besides, there has been no comments/answers on mathematics ...
0
votes
0answers
71 views

Calculating the VaR from a GARCH(1,1) with Student-t innovations

I'm self-studying several questions on Ruey S. Tsay's teaching page. I'm experiencing some difficulty getting the correct answer for final exam 2013 Problem B Question 3. Given a Student-t GARCH ...
0
votes
0answers
48 views

What mean factor behind a yield?

When quoting a yield of a transaction e.g. yield 3.8% behind the yield it is quote "factor" - in this case of a yield of 3.8% it is mentioned in brackets (factor 26.11) . The lower the yield the ...