Questions tagged [var]

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

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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 ...
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153 views

Energy Risk Quant--Any discussion boards for energy related quant topics?

Any discussion boards for energy related quant topics? Like VaR in energy portfolio, and pipeline option pricing.. just want to know where is the best discussion board for such energy specific topics. ...
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1k views

How to compute VaR of a simple equity portfolio?

How do I compute VaR of a simple equity portfolio? I know current weights and can easily access the history of the stocks' daily returns.
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195 views

Do people actually use VaR in professional settings?

VaR seems like such an obviously flawed metric, I am surprised that it seems to be used so much in the private sector. First, the way it is named and the way it is presented often imply it is the ...
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1k 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 - ...
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1answer
1k views

Ratio between Expected Shortfall and Value at Risk for $t$-distribution

If $X$ is a random variable with $t$-distribution of parameter $\mathcal{v}$, how can I prove that $$ \lim_{\alpha \to 1^{-}} \frac{\mathrm{ES}_{\alpha}(X)}{\mathrm{VaR}_{\alpha}(X)} = \frac{\mathcal{...
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793 views

Can a VaR equivalent Volatility (VEV) be negative?

As from title, can a VaR equivalent Volatility (VEV) as defined by KID/PRIIPS law be negative?
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697 views

Historical VaR vs. EVT VaR

We can compute VaR using Historical data and also by Fitting the tails of my Historical data to a GPD(Generalized Pareto Distribution) as shown in EVT and then compute EVT VaR from there. What ...
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77 views

Portfolio VaR of a hedge portfolio (long index, short future): What total exposure to take to calculate VaR?

Imagine a portfolio is made of 20m USD invested in equities and -18m USD of MSCI World futures (sell 18m USD short). The annualised volatility of the 20m USD in equities (Equ.) is 15% and the ...
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251 views

VaR equivalent volatility meaning

I have a hard time with interpreting VeV. I mean - I see its just standard deviation derived from Cornish-Fischer VaR, but I don't really know how to interpret it. The formula for VeV is: ...
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125 views

Monte Carlo VaR w/ Multivariate Normal vs. Parametric

In Aladdin's Monte Carlo VaR, the default setting for the joint distribution of factor returns is multivariate normal. Given that normal distributions do not capture the fat tails seen in empirical ...
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175 views

The BISAM fat-tailed volatility model vs EWMA volatility model

Came across the following marketing material where the company called BISAM (FactSet) aka FinAnalytica (?) has developed following fat-tailed volatility model: $$ r_{t} = \mu + \epsilon_{t} $$ $$ \...
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115 views

Assigning Global VaR to portfolio members

Assuming that I calculate a parametric VaR of a portfolio with 3 assets, and I need to assign the amount each asset (equity) contributes to the VaR. Lets say that: $C$: Is the correlation matrix $w$:...
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642 views

Expected Shortfall Basel III style: what is the idea?

I would like to do a qualitative question about the Expected shortfall in the Basel 3 document. First of all let me introduce few definitions. Suppose to have a portfolio $P$ depending on a family ...
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171 views

What time series and length should be used for a second-order derivative?

Let's suppose that there is an option on a futures contract, the underlying asset for the future is an index, and the future is a cash settled contract. In this case you have a second-order ...
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1answer
504 views

Historical Scenario analysis for stress testing

I am doing historical scenario analysis in order to calculate stressed VAR for which I have taken 2007-2008 US crisis. I have two question in this regard:- 1) As we have to take prices for stocks ...
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154 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 ...
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5k 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 ...
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3k 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 ...
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87 views

Total portfolio VaR greater than aggregated individual VaRs

I am facing something weird in a simulation. I have calculated a portfolio VaR: 100\$. Then I aggregated the VaR for individual position (loans) and obtain: 98\$. I thought it was not possible for the ...
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1answer
62 views

When is the VAR equal to the CVAR

After running an optimisation using a quadratic utility (CRRA) function I calculate an CVAR that is equal to the VAR especially for very small risk-aversion levels ($\gamma$=1 and $\gamma$=2 e.g.). ...
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48 views

Normal VaR for short bond

So I'm short a GBP denominated zero-coupon bond which has a face value of 1 million pounds and a remaining maturity of 6 months. Furthermore, I have to assume that the daily return of a 6-month zero ...
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54 views

Problem in calculating a simple VaR

In Alexander, Gordon J. and Alexandre M. Baptista (2006). Does the Basle Capital Accord reduce bank fragility? An assessment of the value-at-risk approach. Journal of Monetary Economics 53(7), ...
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89 views

Understanding example on VaR

Trying to understand the example below on VaR in Wikipedia. I don't really understand how the 1% VaR is being defined here. Firstly, shouldn't it be 1% Var is 100 since its the amount her looses? And ...
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208 views

How to compute the Value-at-Risk of an equity portfolio hedged using futures contracts?

I would like to have your opinions about how to calculate the VaR of a hedged portfolio using futures contracts. I have tried several "black box" softwares and none of them make too much sense. The ...
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449 views

How to calculate the VaR of a portfolio containing Stocks and ETFs?

I would like to use the approach outlined here to calculate portfolio VaR. However in my case the portfolio also contains ETFs (where I don't necessarily know the fund's total composition. I usually ...
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80 views

Handling option expiration during Monte Carlo simulation

I have equity options in my portfolio that can expire during a VaR calculation (with Monte Carlo). For example the time to maturity of my option is T days but I simulate for T+n days (n > 0). What ...
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108 views

What is a good choice of threshold for Value at Risk?

As far as I know, there is usually a betwixt in choosing the right value for a threshold. A trade off between bias and variance has to be encountered. If a low threshold is chosen, the number of ...
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382 views

Historical VaR on Commodity Physical Forward

Recently came across building Histroical VaR for commodity forward position. Understood from quants guru the best way to calculate VaR is using full re-valuation, Full reval is computationally ...
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354 views

What is the correlation of stock options?

I want to calculate the VaR of two correlated option positions, and I know the correlation between stock price returns. I want to separately calculate $Var_1$,$Var_2$ for option 1 and 2, and then use $...
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111 views

Expected Shortfall alternative formulation

Define: $$q_\alpha(F_L)=F^{\leftarrow}(\alpha)=\inf\lbrace{x\in \mathbb{R}\mid F_L(x)\geq \alpha\rbrace}=VaR_\alpha(L)$$ I want to prove that: $$ES_\alpha = \frac{1}{1-\alpha}\mathbb{E}[\mathbb{1}_{...
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78 views

Resources on VaR modelling for derivative portfolios?

I'm interested in finding resources related to historical VaR calculation for derivative portfolios where both spot and implied volatility changes are accounted for. The resources I've been able to ...
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70 views

Value at Risk (VaR): Normal distribution with gamma distributed volatility

If I was to do a 99% VaR calculation on a portfolio with normally distributed returns $\mathcal{N} (\mu,\sigma)$, the 99% VaR would be $\mu - 2.33\sigma$. Instead of having a constant volatility, let'...
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100 views

How do you handle implied volatility performing a VaR Monte-Carlo simulation using a stochastic volatility process calibrated on the underlying

Say you have a portfolio consisting of options each having a market implied volatility. If you now use some stochastic volatility model like GARCH to calibrate the real world volatility of the ...
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37 views

Summing up two VaRs

I know that normally you can't just add two VaRs straight ahead and you need to use the formula with the sum of squares and the square root. However, in the marking scheme for the task in the image ...
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1answer
79 views

A quick and dirty loss distribution and Credit VaR

I need to create a loss distribution for a credit portfolio as the first steps to estimate the portfolio Credit VaR. I have historical monthly account snapshots (payment history) of all accounts ...
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90 views

Computing Montecarlo VaR for a single asset

I'm trying to understand the procedure to compute the Value-at-Risk for a single asset by implementing the Montecarlo technique. Here it follows the procedure step-by-step in 5 points: selecting the ...
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1answer
150 views

Risk Management methods for Stock portfolio with ~30 stocks

What is ideal Risk Management method/methods s for stock portfolios with 25-30 stocks and around 50.000 USD invested in those stocks. Every stock bought will be kept in the portfolio for 1 to 12 ...
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132 views

What are some of the most important/interesting Risk measures to watch?

I am wondering what are some of the more important/interesting risk measures to watch, particularly in FX markets. So far I'm watching the following: Greeks Tail moves AKA VaR (left and right tail ~ ...
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303 views

Calculating HIstorical VaR with short time series

Intuitively, Historical VAR is an approach which assumes that in the past data, we have observed everything that can happen, so we consider the worst case(tail). However, when your equity/instrument ...
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128 views

How to adjust corporate actions for VaR

I am using variance co variance matrix for calculating the VaR. Now if the some corporate action comes in between like stock split, resulting a huge VaR number on that particular day as the volatility ...
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162 views

Monte Carlo VaR assuming logistic distribution

I have a Monte Carlo model which measures the Value at Risk (VaR) for given portfolio. I use the geometric brownian motion to model the prices. But let's say I assumed the returns of prices follow the ...
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1answer
136 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 ...
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Longer / Shorter period loss

I am struggling on I think a quite simple issue. Let's take a portfolio of 100 loans. If we assume they are independent, each loan’s default is a Bernoulli with parameter $p=0.01$ over a certain time ...
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Difference between Vasicek and Gordy models

I'm trying to understand what Gordy [1] added to Vasicek [2] model (the core of the IRB formula of Basel Accords). Is it correct to say the Vasicek shows that the portfolio loss conditional on $Y$ ...
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Can you predict MTM gain or losses on future contract?

I am working on a structured product where I am investing some percentage of invested amount in futures contract. I have created a bull put strategy and I will calculate the delta positions of that ...
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Advantage of copula over estimation based on historical data

It seems to me hard to intuitively understand the concept of copulas and their advantages. For example, why would it be better to estimate value at risk of portfolio by modelling its asset returns ...
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ES using historic simulation

Why is the data obtained from 91-100 days all eliminated from the calculation of the 1-day 95% ES? My interpretation is because the first day to calculate the 95% ES should be the 90th day? But I can'...
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Kupiec Test Backtesting VaR

I am currently analyzing the Kupiec test used for backtesting $VaR$. Suppose that I backtest a $VaR$ system for $n$ days (for example 250), with a confidence interval of $1-\alpha$ (for example a $1-\...
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293 views

Manually calculating and backtesting VaR and CVaR from DCC-GARCH R

I estimated a GARCH fit to the log returns of three series (CAC 40, a french real estate index and french T10 bond yield series) using rugarch. I then manually ...