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  2. How to use beta to evaluate a stock’s risk - AOL

    www.aol.com/finance/beta-evaluate-stock-risk...

    To calculate beta, investors divide the covariance of an individual stock (say, Apple) with the overall market, often represented by the Standard & Poor’s 500 Index, by the variance of the ...

  3. Alpha vs. beta in investing: What’s the difference? - AOL

    www.aol.com/finance/alpha-vs-beta-investing...

    How to calculate beta. Beta is calculated by taking the covariance between the return of an asset and the return of the market and dividing it by the variance of the market. The measure is ...

  4. Estimation of covariance matrices - Wikipedia

    en.wikipedia.org/wiki/Estimation_of_covariance...

    The sample covariance matrix (SCM) is an unbiased and efficient estimator of the covariance matrix if the space of covariance matrices is viewed as an extrinsic convex cone in R p×p; however, measured using the intrinsic geometry of positive-definite matrices, the SCM is a biased and inefficient estimator. [1]

  5. Covariance matrix - Wikipedia

    en.wikipedia.org/wiki/Covariance_matrix

    Throughout this article, boldfaced unsubscripted and are used to refer to random vectors, and Roman subscripted and are used to refer to scalar random variables.. If the entries in the column vector = (,, …,) are random variables, each with finite variance and expected value, then the covariance matrix is the matrix whose (,) entry is the covariance [1]: 177 ...

  6. Covariance - Wikipedia

    en.wikipedia.org/wiki/Covariance

    The sign of the covariance of two random variables X and Y. In probability theory and statistics, covariance is a measure of the joint variability of two random variables. [1] The sign of the covariance, therefore, shows the tendency in the linear relationship between the variables.

  7. Portfolio Beta vs. Stock Beta: What's the Difference?

    www.aol.com/finance/calculate-beta-portfolio...

    Continue reading → The post How to Calculate the Beta of a Portfolio appeared first on SmartAsset Blog. Investors, whether beginner or seasoned professionals, all have a threshold for risk. Some ...

  8. Covariance and correlation - Wikipedia

    en.wikipedia.org/wiki/Covariance_and_correlation

    With any number of random variables in excess of 1, the variables can be stacked into a random vector whose i th element is the i th random variable. Then the variances and covariances can be placed in a covariance matrix, in which the (i, j) element is the covariance between the i th random variable and the j th one.

  9. Single-index model - Wikipedia

    en.wikipedia.org/wiki/Single-index_model

    Covariance among securities result from differing responses to macroeconomic factors. Hence, the covariance of each stock can be found by multiplying their betas and the market variance: The single-index model assumes that once the market return is subtracted out the remaining returns are uncorrelated: