A theoretical framework for analyzing investment portfolios based on their expected return and risk.
0
votes
0answers
19 views
How is breadth for Information Ratio Calculated
An alternative definition of the information Ratio (sharpe ratio) is:
$IR = IC\sqrt{BR}$
I have been reading Grinold and Kahn. I have the following questions for calculating BR:
Q1. If 500 stocks ...
2
votes
1answer
50 views
Examination of Betting Against Beta
http://pages.stern.nyu.edu/~lpederse/papers/BettingAgainstBeta.pdf
In this article the authors explain a theory/strategy called Betting Against Beta. My background is more in Math rather than finance ...
0
votes
0answers
31 views
Compute the beta of portfolios constructed from the Betting Against Beta strategy [on hold]
http://pages.stern.nyu.edu/~lpederse/papers/BettingAgainstBeta.pdf
I am trying to understand how to apply the Betting Against Beta strategy. Let's for instance consider two stocks A and B with $\...
1
vote
0answers
41 views
Problems with Black-Litterman: negative portfolio weights, and very poor returns
I am trying to implement the Black-Litterman model using own-defined views matrix (from consensus analysts). However, I have encountered the problems of negative portfolio weights in some periods, and ...
2
votes
1answer
120 views
Why universal portfolio (by T.Cover) always give uniform allocation
Here I use the the open-source project Universal-Portfolio on Github https://github.com/Marigold/universal-portfolios
to test the up algorithm given by T.Cover. However, I find that up algorithm ...
1
vote
1answer
72 views
R PortfolioAnalytics
I am not able to find PortfolioAnalytics package for windows from CRAN. New to R, will greatly appreciate any help how to find and install this package.
1
vote
0answers
63 views
Mean Variance Optimization of 2000 pairs of securities (Python)
I would like to take the opportunity to ask for your help on an assignment I'm trying to complete.
For this 'Modern Robo Advisory' course we are asked to solve a (target) goal-based investment ...
1
vote
2answers
41 views
What is the return of risky asset in direct utility optimization probem?
I am trying to do this portfolio optimization for a one-month investment between S&P 500 as a risky asset and one risk-free asset:
Assume that I have a power utility function, a risk-free rate ...
0
votes
0answers
46 views
How to allocate additional capital to an already fully balanced portfolio?
Most sources seem to talk about allocating a fixed amount of capital to a portfolio, and then periodically rebalancing it, as far as i can tell. Assuming an already balanced portfolio, how would one ...
1
vote
1answer
167 views
Active Portfolio Management: What is the logic behind this equation? [closed]
In the CFA Curriculum Level II Readings (link) it is stated without further comment that:
$(SR_{p})^2 = (SR_{b})^2 + IR^2 $
where,
$(SR_{p})$ = Sharpe Ratio of an actively managed portfolio;
$(...
1
vote
1answer
297 views
How can I find the portfolio with maximum Sharpe Ratio - Using Lagrange Multipliers
In Markowitz' portfolio theory we can construct portfolios with the minimum variance for a given expected return (or vice versa). Across expected risks, this traces out the well-known efficient ...
1
vote
1answer
127 views
Many quants optimize sharpe ratios, sortino ratios, or anything of the form A/B. What about maximizing something of the form (AB)/(CD)?
The Sharpe ratio is defined as return/risk, generally as mean(ret)/sd(ret), where ret represents the data set of returns of an investment. However, I have seen other ratios that I also like. What I ...
0
votes
0answers
45 views
Modern Portfolio Theory Proof--how does increasing number of stocks reduce variance
$Var(Portfolio) = [\sum_{i=1}^N wi^2 * (\sigma_i)] $+ All Covariance Terms
Let's say there are two stocks whose covariance is -1; then how would the efficient frontier of the portfolio consisting of ...
0
votes
0answers
33 views
Continuous returns in BS-market
Let's assume we are in a Black-Scholes market. The price processes in
the BS-market are given by $dP_0(t)=P_0(t)rdt, P_0(0)=1$
$dP_i(t)=P_i(t)\cdot(\mu_i dt + \sigma_idW(t))=P_i(t)\cdot \left(\...
0
votes
0answers
69 views
Difference between binomial and CRR model
What is the difference between a binomial and CRR model. I know what a binomial model is, but in CRR also there are subintervals where prices change like a one period binomial. I think I haven't ...
0
votes
0answers
68 views
Should Fama French Factors lagged?
I am estimating returns of individual components of the SP500 using a 3-factor FF model. I am using the estimated returns to build a simulated trading strategy updated daily, where I will construct a ...
4
votes
1answer
272 views
How to choose a tangency portfolio without a risk-free rate
How do you choose an optimal portfolio from the efficient frontier if no risk-free rate is given?
I know that if there exists risk-free asset, then you would combine a portfolio from the efficient ...
2
votes
1answer
147 views
Rockafellar-Uryasev mean-CVaR optimiztion
In Rockafellar-Uryasev 2001 paper (http://www.ise.ufl.edu/uryasev/files/2011/11/CVaR1_JOR.pdf) the mean-CVaR optimization can be written as a linear programming optimization problem as:
$$P_{CVaR} = \...
7
votes
1answer
111 views
Finding a minimum variance portfolio when using a regulariser?
I am aware that the minimum variance portfolio of a market with $n$ securities can be shown to be:
\begin{equation}
w^* = (1^T_n\Sigma^{-1}1_n)^{-1}\Sigma^{-1}1_n, \\ s.t. \ \ 1^T_nw = 1
\end{...
0
votes
2answers
410 views
What’s the derivative of the sharpe ratio for one asset? Trying to optimize on it for a model
It seems most Sharpe ratio derivations seem to be for portfolios but I am just tracking a single asset?
$SR = (r_p - r_f) / \sigma_p$ but what would I derive with respect to for an optimization/ ...
3
votes
1answer
694 views
marginal risk contribution formula
I am trying to understand and implement the standard 'marginal risk contribution' approach to portfolio risk and hoping to reconcile the formulae provided for its calculation in different sources. ...
0
votes
0answers
41 views
Mean-variance optimization using one-step-ahead forecasts
I need to optimize my portfolio using as expected returns the one-step-ahead forecasts produced recursively by a VAR model. I tried to use
...
0
votes
0answers
62 views
optimize.portfolio.rebalancing ROI - transaction costs error
New to using PortfolioAnalytics (and fairly new to R in general) and am encountering an error when running optimize.portfolio.rebalance. Below you can see the code ...
1
vote
1answer
37 views
Portfolio optimization of unequal length back-tests
I have a portfolio of assets. For each asset I have a back-tested time series of daily profits. I'm tying to optimize, using the correlation of daily returns, to minimize the total draw-down of the ...
-1
votes
1answer
56 views
Multi-Factor Beta Help
I'm supposed to find a risk factor that could explain a stock (I chose Netflix) returns.
Then, I am to calculate the beta with respect to the factor I suggested as part of a multi-factor model with ...
1
vote
0answers
85 views
Portfolio risk decomposition using historical data: which weights to use for assets?
I am trying to decompose portfolio risk given historical returns of each asset in the portfolio. For a basic 2 asset portfolio, the portfolio risk is given as
$$σ_p^2 = w_x^2 \cdot σ_x^2+ w_y^2 \...
6
votes
3answers
345 views
Generalized Mean Variance Portfolio
Utility based portfolio optimization deals with the problem of finding the optimal portfolio $x_T$ by maximizing the utility/objective function $O(x_T,x_0)$ where $x_0$ is the current portfolio.
In ...
0
votes
0answers
30 views
What is the difference between expected return and percentage of assests allocated?
I'm trying to apply the Modern Portfolio Theory in the area of computer networks. The task is to select between multiple services (assets). Each service has some properties such as response time. Each ...
0
votes
0answers
34 views
Calculating Marginal Contribution to Correlation from PnL Stream
Is there a way to calculate marginal contributions to correlation, like we would calculate marginal contribution to risk?
Basically, figure out how much each security (which may be in both portfolios ...
3
votes
0answers
110 views
Trouble computing the VaR for Student's t-distribution for a minimum-variance portfolio composed of four cryptocurrencies (BTC, ETH, LTC, and XMR)
I have modelled the time-series of daily log-returns from August 2015 to October 2017 of a minimum-variance portfolio composed of four cryptocurrencies (BTC, ETH, LTC, XMR) by fitting the data to four ...
-4
votes
1answer
90 views
Derivation of arithmetic variation of a portfolio over multiple periods [closed]
I am very confused on how to derive the attached equation (15).
Would someone be kind enough to walk me through the proof?
0
votes
0answers
362 views
Negative slope security market line
I downloaded weekly data of Stock prices from yahoo finance and computed the expected returns and betas. I found the betas using the ALL ordinary price index as the market portfolio. I then regressed ...
0
votes
0answers
45 views
How do I calculate my Portfolio Variance when some of my assets are loans?
Following Modern Portfolio Theory, I am trying to calculate the covariance between the different assets in my portfolios.
To calculate the covariance I need to know the Weight (which I can obtain ...
1
vote
1answer
76 views
How to calculate the contribution (%) of an asset to the global correlation of the portfolio?
I have a portfolio X with weights $w_i$. I am trying to find the contribution $\xi_i$ of asset $i$ to the total correlation $\rho_{XM}$ of the portfolio X to an index M. I can't find these ...
0
votes
1answer
118 views
Private Equity: Direct Alpha vs Excess IRR
I'm trying to understand the advantages and disadvantages of using Direct Alpha versus Excess IRR for computing excess returns over a market index for private assets.
Wikipedia references a highly ...
5
votes
4answers
234 views
Why do anomalies disappear after they get detected?
In financial markets, anomalies refer to situations when a security or group of securities performs contrary to the notion of efficient markets, where security prices are said to reflect all available ...
1
vote
1answer
78 views
Variance of returns on a portfolio
This must be very basic, but I don't seem to be able to express the variance of returns on a portfolio in terms of variances-covariance sum of returns of its constituents, which seems to be what is ...
1
vote
0answers
52 views
Process for a portfolio of stocks where each share follows a log-normal process
Given a portfolio of shares $I = \sum{w_iS_i}$ for some fixed weights $w_i$ where each stok $S_i$ has a log-normal distribution, what is the process / distribution followed by the portfolio? That is, ...
2
votes
0answers
46 views
Covariance Matrix: Calculating Error [duplicate]
I have a sample covariance matrix that is non positive-semi definite (due to missing data points). I am looking at a number of techniques to 'fix' my covariance matrix and make it positive semi-...
0
votes
1answer
43 views
What CAPM/Financial ratios involve kurtosis?
Simple question, what universally accepted financial ratios involve kurtosis? I'm not looking for a made up one. I want something that academics may have discussed.
4
votes
1answer
189 views
Optimisation with strong correlated Assets
I have the following settings:
The allowed traded assets consists of 1 bank account, 1 non dividend paying stock and 19 call options whose maturity is in 30 days. I want to find an optimal static ...
0
votes
1answer
304 views
MPT Tangent Portfolio: Buck for the Bang Ratio
The $R_{TP}$ is the tangent portfolio return, but I don't understand the step regarding $\frac{dV(R)}{dw_n}$, you apply this, and how come it get rids of the summation?
5
votes
1answer
612 views
Calculating alpha and its meaning
According to wikipedia, CAPM model is described by:
$E(R_{i})=R_{f}+\beta _{{i}}(E(R_{m})-R_{f})$
And according to website such as http://investexcel.net/jensens-alpha-excel/,
$\alpha = E(R_{i}) - ...
1
vote
1answer
688 views
What is the difference between the Single Index Model and Multi-Index Models in computing the variance-covariance matrix of stock returns?
Would be very grateful for some help in comparing the single index model with other multi-index models in computing the variance-covariance matrix.
0
votes
1answer
88 views
Is it better to express a currency position through multiple pairs?
I use a trend-following approach where I look for trends in various currency pairs such as GBP/USD or EUR/USD and then take a position in the Spot currency. I measure the performance of my strategy by ...
2
votes
2answers
58 views
Explanations regarding Minimum Variance Portfolio
I am sorry in advance if this question seems a bit stupid but during my class my lecturer said that:
"The traditional estimator of the variance-covariance matrix is the sample covariance. However ...
2
votes
2answers
149 views
Backtest Results needed to Model Validate my Modern Portfolio Theory model
this is my 1st post, and I hope someone can help me! I have been searching for a week now without any luck
I have built a Portfolio Allocation model based on Modern Portfolio Theory (MPT). I now need ...
1
vote
0answers
96 views
Zero-beta assets and the Sharpe-Lintner CAPM
I'm reading The Capital Asset Pricing Model: Theory and Evidence (Fama and French, 2004) and came across the following statement:
"A risky asset’s return is uncorrelated with the market
return—its ...
2
votes
2answers
220 views
Portfolio optimisation with conditional weight restrictions among asset
I want to optimise a portfolio of assets from different countries (A,B,C...) where the set of all country-asset combinations is (A1, A2, A3, A4.... B1, B2, B3... C1...). I want to include a ...
3
votes
2answers
343 views
Does CAPM hold for markets with two risky assets?
Presentations of the CAPM often include statements similar to this:
While idiosyncratic risk can be "diversified away", systematic risk cannot, which is also expressed in the CAPM, which states ...
