Questions tagged [coherent-risk-measure]

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22
votes
3answers
9k 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 ...
17
votes
3answers
4k 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} \...
11
votes
2answers
12k views

What is the meaning of subadditivity in a risk measure?

The subadditivity reads: $\rho(X_1+X_2) \leq \rho(X_1) + \rho(X_2)$ What is the meaning of this condition? I can vaguely accept that one should diversify the investment portfolio. Or, I can ...
2
votes
1answer
939 views

annual excess returns from CAPM on monthly total returns

I want to calculate annual excess returns on portfolios using monthly returns for a CAPM (for the assets in the portfolio as well as for the benchmark), in order to have more information on the ...