Questions tagged [modern-portfolio-theory]

A theoretical framework for analyzing investment portfolios based on their expected return and risk.

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1answer
105 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 ...
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65 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, ...
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58 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-...
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59 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.
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1answer
220 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 ...
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1answer
980 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?
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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}) - ...
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1answer
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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.
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1answer
128 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 ...
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2answers
122 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 ...
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2answers
248 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 ...
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0answers
191 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 ...
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2answers
374 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 ...
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748 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 ...
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81 views

Confusion about Assumptions in Markowitz Optimization

Setup and Definition of Terms Supposed that we have a universe of possible securities $\mathcal{S}$. We wish to construct an "optimal" portfolio, which will be represented by proportional weights $\{...
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1answer
1k views

Given two risky stocks calculate the rate of return, standard deviation, beta, and risk-free rate

Consider a world where there are only two risky stocks, $A$ and $B$, whose details are listed in the table below: Furthermore, the correlation between the returns of stocks $A$ and $B$ is $\rho_{A ...
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1answer
222 views

Using CAPM to derive the following

Background Information: Say there are $s = 1,\ldots,S$ possible future outcomes (states) with known probabilities $\pi_s > 0$, $\sum_{s=1}^{S}\pi_s = 1$. Define the expected payoff as $\mathbb{E}_\...
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100 views

Given three stocks what is the fraction of each stock's risk is diversified away

Consider an equally weighted portfolio of three stocks, each of which is independently distributed of the others but have the same risk. I.e., $cov(r_i, r_j) = 0$; $\forall i \neq j$, and $\...
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49 views

How to hedge a MV portfolio against crises

I have constructed an adjusted Mean-Variance portfolio optimization method that optimizes the exposure in a set of X assets. The portfolio works perfectly fine during normal periods (even when there ...
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1answer
1k views

PortfolioAnalytics [R] - optimize.portfolio.rebalancing error

New to using PortfolioAnalytics (and fairly new to R in general) and am encountering an error when running optimize.portfolio.rebalance -- see below: Error in ...
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3answers
318 views

Portfolio Theory: Why is so much effort put into the reduction of estimation errors?

In MPT, very much effort by researchers is put into developing methods and techniques to handle the rather poor performance of the estimated means, variances and covariances. There are shrinkage ...
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3answers
215 views

In portfolio theory, has volatility a logical place as an asset class?

Some years ago, a colleague made the argument that volatility should be thought of as an asset class. That means that taking exposure to implied volatility, in the form of volatility bonds, or long ...
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1answer
207 views

Portfolio Theory: Currency Risk

It seems to me that Currency Risk can be diversified away and hence one should not get paid for taking it. Do you agree?
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505 views

How to take into account currency risk when optimizing portfolio?

I have a portfolio of foreign stocks. All stocks are denominated in foreign currency. I need to compute returns and risk metrics in national currency which is different from stocks currency. Stocks`s ...
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1answer
2k views

What is the Beta of an efficient portfolio?

I'm beginning to learn Portfolio Theory and I want to understand the Beta and its value for efficient portfolios. An efficient portfolio is the one that gives the best expected return for an ...
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1answer
511 views

Why did Markowitz not derive an equation for the efficient frontier?

Currently, I´m studying portfolio management and portfolio selection. The founder of the MPT is Harry Markowitz, of course. But reading his famous article from 1952 and his book from 1959 (actually, I ...
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1answer
159 views

Show that there exists a fully invested portfolio such that the covariance between their returns is zero

Background Information: I came across this question in chapter 2 of Active portfolio Management by Grinold and Kahn. It pertains to the efficient frontier which is displayed below: Question: If $...
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343 views

Mean-variance portfolio returns illogical weights

I have a dataset with 5 assets. I apply mean-variance portfolio: ...
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2answers
159 views

How to prove that every point on the capital market line corresponds to a unique portfolio

Prove that every point on the capital market line corresponds to a unique portfolio. Attempted proof I know that each point on the capital market line represents a linear combination of the risk ...
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261 views

Annualization of coskewness and cokurtosis

I am constructing a mean-variance-skewness-kurtosis portfolio based on monthly data with a holding period of one year. Meucci describes how to annualize higher order moments in general, but not how to ...
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1answer
2k views

Portfolio optimization subject to transaction costs

Mean-Variance portfolio optimization attracted lots of attention in this forum so far. I am interested in the effect of incorporating transaction costs into the decision framework and I would like to ...
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2answers
3k views

Risk contribution of part of a portfolio

Is it quantitatively sound to say that if I have assets $x, y,$ and $z$ in a portfolio, and that the total variance of the portfolio is defined as $\sigma_p ^2 = w_x^2\sigma_x^2 + w_y^2\sigma_y^2 +...
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2answers
4k views

Fama French & Solving for Alpha

This is a question about comparing results from the Fama french 3 factor model. I have not physically done this, but let's assume a Fama French 3 factor regression was performed for Coca-Cola (KO) ...
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2answers
471 views

Maximum Certainty Equivalent Portfolio with Transaction Costs

Out of curiosity I tried to compute the portfolio weights of a maximum certainty equivalent allocation, however, by incorporating (quadratic) transaction costs. However, my result is not as intuitive ...
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1answer
48 views

Verifying value of claim as an expectation

Background: We have so far taken the bond B to be deterministic for simplicity, but some reflection shows that this is not in any way necessary. Everything works out the same way with a stochastic ...
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1answer
59 views

Do we have arbitrage if the probability measures are less than zero

Background Information: This question follows from here It is tempting to write $$V_0(X) = \beta\left[\left(\frac{\beta^{-1}S_0 - S_1(d)}{S_1(u) - S_1(d)}\right)X(u) + \left(\frac{S_1(u) - \beta^{-1}...
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1answer
116 views

Value of a perfect hedge

Background Information: The price of a portfolio at time $t$ ($t = 0 ,1$) is $$V_t(\pi) = \phi S_t + \psi B_t$$ The portfolio $\pi$ is a perfect hedge for the claim $X$ if $V_1(\pi) = X$ a.s. as ...
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87 views

Using GO GARCH to optimize a yearly-rebalanced portfolio based on daily data

Is it reliable to optimize portfolio weights on a yearly-rebalanced portfolio based on the Generalized Orthogonal GARCH (GO-Garch) covariance, coskewness, and cokurtosis matrices with the rmgarch R-...
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1answer
185 views

List of risk-averse utility functions

In the context of optimal portfolio allocation, I am looking for a (possibly exhaustive) list of risk-averse utility functions verifying part of the so-called Inada conditions. Essentially, I am ...
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2answers
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Understanding the Weights of an Optimal (Mean-Variance) Portfolio

I have calculated an optimal portfolio, using a historical covariance matrix, and determined the weights of n risky assets in the optimal portfolio. The utility function I minimize is represented by ...
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2answers
4k views

Formula for Optimal Portfolio of 2 Assets when No Shorting Allowed?

I am looking for a formula to calculate the weights of two risky assets that produce the optimal portfolio (i.e highest Sharpe ratio). So far I have found the following formula from a website of ...
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3answers
16k views

What value should the risk free monthly return rate be (Sharpe ratio calculation)?

In calculating an annualized Sharpe ratio using monthly returns, what is commonly used as the value for the risk free rate? I am using this formula: ...
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2answers
81 views

How exactly are correlated defaults used/analyzed?

I've read a lot about correlate defaults but I can't seem to understand how they're used practically in a portfolio theory setting. Suppose I have two (?) companies, X and Y, and historic default ...
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118 views

Relation between mean and variance of a portfolio in modern portfolio theory:

I hope that this is the right place to ask my question! Let a market with $N\ge1$ risky assets and denote by $(R_i,i=1,\cdots, N)$ their returns and $R$ the vector of these $N$ returns. In addition, ...
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3answers
399 views

Sharpe Ratio and your annualization

My question is related on this How to annualize Sharpe Ratio? but is a bit different. Under assumpion of IID returns, if excess return is positive, the SR increase over time horizon, with factor $\...
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1answer
127 views

What does an optimized portfolio really tell us?

I am very new to this field, and have very recently started doing some self study on this topic. After reading some papers and reproducing some of the results in them, I am not very clear about what ...
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1answer
621 views

Two fund separation when there's a risky asset?

I am currently reading a book which begins its portfolio theory section with the case with $n$ risky assets where it proves that 2-fund separation applies (any minimum variance portfolio is a linear ...
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1answer
378 views

What does each bar in the empirical average eigenvalues spectrum of the correlation matrix of log-returns of stocks represent?

An example diagram, taken from this paper, looks like follows: What is its physical interpretation? The highest eigenvalue, the paper says, represents market mode. So, what does the difference in ...
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Problem with determining weights in tangency portfolio (2 risky assets)

I use the following well known formula in order to determine the weight of asset i in the tangency portfolio (in the case of two risky assets): $w_{i,T}=\frac{\sigma[r_2]^2E[R_1]-\sigma[r_1,r_2]E[R_2]...
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1answer
2k views

How to calculate the global minimum variance portfolio in R?

I am attempting to use the globalMin.portfolio command to calculate the global minimum variance portfolio in RStudio. My code is as follows (note that several ...