The possibility that a negative event (such as a loss) will happen.

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31
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5answers
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 ...
22
votes
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 ...
19
votes
4answers
6k views

What is the best way to “fix” a covariance matrix that is not positive semi-definite?

I have a sample covariance matrix of S&P 500 security returns where the smallest k-th eigenvalues are negative and quite small (reflecting noise and some high correlations in the matrix). I am ...
17
votes
7answers
5k views

How does the “risk-neutral pricing framework” work?

I've struggled for a long time to understand this - What is this? And how does it affect you? Yes I mean risk neutral pricing - Wilmott Forums was not clear about that.
17
votes
2answers
659 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 ...
16
votes
2answers
578 views

How do macro funds manage risk and model asset returns? Do they use factor models?

Some of the largest funds in the world are entirely macro-based: Soros, Brevan Howard, Bridgewater. They trade across asset classes, and seemingly with very concentrated allocations. What type of risk ...
15
votes
1answer
957 views

Portfolio optimization with monte carlo sampling from predictive distribution

Let's say we have a predictive distribution of expected returns for N assets. The distribution is not normal. We can interpret the dispersion in the distribution as reflection of our uncertainty (or ...
14
votes
4answers
2k views

How are risk management practices applied to ML/AI-based automated trading systems

A potential issue with automated trading systems, that are based on Machine Learning (ML) and/or Artificial Intelligence (AI), is the difficulty of assessing the risk of a trade. An ML/AI algorithm ...
13
votes
2answers
672 views

Concentration risk in credit portfolio

How do you model concentration risk of credit portfolio in IRB/Basel II framework?
11
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2answers
3k views

How does left tail risk differ from right tail risk?

How does left tail risk differ from right tail risk? In what context would an analyst use these metrics?
10
votes
3answers
1k views

Is Conditional Value-at-Risk (CVaR) coherent?

When the risk is defined by a discrete random variable, is CVaR a coherent risk measure? I stick to the following definition of CVaR: $$ CVaR_\alpha(R) = \min_v \quad \left\{ v + \frac{1}{1-\alpha} ...
10
votes
4answers
2k views

What is a “coherent” risk measure?

What is a coherent risk measure, and why do we care? Can you give a simple example of a coherent risk measure as opposed to a non-coherent one, and the problems that a coherent measure addresses in ...
10
votes
2answers
734 views

When should you build your own equity risk model?

Commercial risk models (e.g., Barra, Axioma, Barclays, Northfield) have evolved to a very high level of sophistication. However, all of these models attempt to solve a very broad set of problems. ...
10
votes
1answer
297 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 ...
10
votes
3answers
219 views

Does entropy pooling apply to distributions with time-varying drift?

I have a returns process that is drawn from a normal distribution with a nonlinear time-varying drift, so I was wondering if the entropy pooling method still applies or if I need an invariant ?
9
votes
3answers
594 views

better estimator of volatility for small samples

One commonly used sample estimator of volatility is the standard deviation of the log returns. It is indeed a very good estimator (unbiased, ...) when the sample is large. But I don't like it for ...
9
votes
2answers
738 views

What is the relationship between risk aversion and preference for skewness and kurtosis in portfolio optimization?

Is there any relationship between the risk aversion coefficient in an individual's utility function (commonly used in portfolio optimization) and the preference for higher moments such as skewness and ...
9
votes
4answers
1k views

Is the risk-free rate really limited by inflation?

In all the classic texts on equities derivatives, there is an assumption of the risk-free rate r. We can immediately dismiss the concept of a fixed rate; all interest rates are variable (and ...
9
votes
1answer
574 views

How are Expected Shortfall and Variance related?

I would like to know how Expected Shortfall $SF_\alpha$ and variance $\sigma^2$ are related. If I follow what Aaron Brown answered in this post, when the underlying distribution is Normal with ...
9
votes
1answer
628 views

Models for measuring insurance risk exposure

I've recently begun working as a quant for a large bank, and one of my first tasks will be to improve the model determining the risk exposure of their insurance portfolio. The portfolio is fairly ...
8
votes
5answers
2k views

Why is the Drawdown measure not used for portfolio optimization?

I was asked yesterday by a colleague why we are doing asset allocation using optimizers which target, for a minimum expected return: the portfolio with the minimum variance or the portfolio with ...
8
votes
4answers
678 views

What are the risk factors in analysing strategies?

What do you think of strategies displayed on timelyportfolio.blogspot.com? I really like the fact that there is some code to reproduce the strategies, but they seem very elementary because he does ...
8
votes
2answers
2k views

Equity Risk Model Using PCA

I'm trying to build a simple risk model for stocks using PCA. I've noticed that when my dimensions are larger than the number of observations (for example 1000 stocks but only 250 days of returns), ...
8
votes
2answers
568 views

Minimizing Correlation

Is there a quantitative method in monitoring trades to reduce the possibility of correlated trades?
8
votes
1answer
637 views

How to compute modified-CVaR in the PerformanceAnalytics package?

My objective is to measure the modified-CVAR for a portfolio given its weights and matrix of security returns. Luckily the wonderful package PerformanceAnalytics has an ES() function that does just ...
8
votes
3answers
595 views

Price of Brent versus West Texas Intermediate

As of right now, the price of Brent Crude is $\$$111.59/bbl and the price of WTI Crude is $\$$98.36/bbl. I'm well aware that futures markets don't set the spot price for oil, but actual ...
8
votes
1answer
479 views

Fama-French 3-factor model: factors implying risk

The Fama-French three-factor risk model is given by $$ r=R_f+\beta_m(K_m-R_f) + \beta_s\cdot\mathit{SMB}+\beta_v\cdot\mathit{HML}+\alpha $$ where $r$ is the return, $R_f$ is the risk-free rate, $K_m$ ...
8
votes
1answer
38 views

What are useful indexes for rapid evaluation of country economic risk?

The World Economic Forum Global Competitiveness Report offers a comprehensive view of individual country risk/reward. There has been an explosion of these types of indexes over the past few years. ...
8
votes
0answers
294 views

performance of historical VaR parameters

An historical VaR measure is parameterized in terms of the confidence level and also number of periods. Specifically, the $\alpha$% T-period VaR is defined as the portfolio loss x in market value over ...
7
votes
4answers
19k views

What are some examples of non-financial risks and contingency plans?

There are many online sources about common risk factors in investing and trading e.g. market risk, credit risk, interest rate risk. There are various factor models (Fama-French, Carhart) and risk ...
7
votes
2answers
328 views

Do you know a good article on ETF's counterparty risk analysis?

I am at the moment considering investing into ETFs, but I am looking first to understand how these products really work. Indeed, it is my understanding that ETF can vary in terms of structure, thus ...
7
votes
2answers
1k views

How to apply risk-parity portfolio construction to a dollar-neutral portfolio?

Long-only risk-parity portfolios have proliferated in recent years. An optimized long-only risk-parity portfolio requires that the asset weight * marginal contribution to risk of the asset is ...
7
votes
2answers
615 views

How to manage equity portfolio risk intraday?

Lets assume that I have an equity strategy that generates signals intraday to buy and sell. I run this strategy across the SP500 names. Now within my strategy I want to incorporate a method to help me ...
7
votes
1answer
1k 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 ...
7
votes
1answer
1k views

What is the basis risk between cash and futures government bonds?

I am currently working in a team responsible for maintaining a simple risk application for our bond desk and I am interested in knowing how to provide some sort of basic basis risk metric. Our desk ...
6
votes
5answers
658 views

Indicators and research for stress-based investment strategies

In reference to this paper: Can risk aversion indicators anticipate financial crises? and the investable UBS Risk Adjusted Dynamic Alpha Strategy: ...
6
votes
4answers
1k views

What does it mean to modify the factor loadings of a credit risk model?

I came across an example where a well-known weakness of a credit risk model was dealt with by augmenting some of the existing risk factors via increased factor loadings. This made the the model more ...
6
votes
1answer
366 views

What distribution should I apply to estimate the likelihood of extreme returns?

Say I have a limited sample, a month of daily returns, and I want to estimate the 99.5th percentile of the distribution of absolute daily returns. Because the estimate will require extrapolation, I ...
6
votes
2answers
2k views

Why using 3 months forward to hedge fx risk on a fund of funds portfolio?

In my previous job, a fund of funds, they used 3 months forward FX contracts (renewed every 3 months) to protect their portfolio against currency risk. If I do understand why forwards are useful for ...
6
votes
1answer
1k views

How can I use Entropy-pooling of Atillio Meucci to constuct a portfolio?

I am trying to get my hands on Entropy Pooling which was introduced by Meucci in this paper. As an example, assume I want to construct a portfolio with five stocks and I have my view on CVaR. How ...
6
votes
3answers
677 views

cointegration applied to Portfolio Construction & Risk management

There are all sorts of applications of cointegration to generating alpha on mean-reverting timeseries: comparing spot vs. futures, bond spreads, identifying mean-reverting residuals, etc. But there ...
6
votes
4answers
317 views

Large (5K-10K) non positive definite (particularly near singular) covariance matrices and treatments for Cholesky decomposition

I have a very large covariance matrix (around 10000x10000) of returns, which is constructed using a sample size of 1000 for 10000 variables. My goal is to perform a (good-looking) Cholesky ...
6
votes
2answers
210 views

Is it better to grade hedging strategies based on the sum of absolute or squared hedging errors?

Let's say I have one strategy that has a hedging error of: 2, 2, -2, -2 Let's say I have another strategy that has a hedging error of .5, .5, 3, 3 Would it be a better idea to grade the hedging ...
6
votes
1answer
426 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
0answers
149 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
3answers
776 views

Gamma vs. Volatility Risk

Original Question: What is the link between Gamma and the Volatility Risk? It leads me to ask: - What is the Volatility Risk definition and what are the good practices to measure it? Thinking about ...
6
votes
0answers
198 views

Optimization procedure for entropy pooling

I was wondering if those who used the entropy pooling code provided by Attilio Meucci had issues with the optimization procedure (especially regarding the fminunc function in Matlab). When I stress ...
5
votes
4answers
782 views

Do low volatility stocks outperform high volatility stocks over the long run?

A recent article from Forbes seems to indicate that low volatility stocks outperform high volatility stocks over the long run. Does anyone have any supporting or contradicting evidence to this claim? ...
5
votes
3answers
108 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
1answer
816 views

Value at Risk backtesting (kupiec)

I m doing my research on estimating Value at risk using different assumptions on volatility and then compare my results based on backtesting. I obtained results and just on question based on my ...