Mean-variance analysis is used to identify optimal portfolios based on expected returns, variances, and covariances of asset returns. The minimum-variance frontier shows the efficient combinations of expected return and risk. The efficient frontier begins with the global minimum-variance portfolio and provides the maximum expected return for a given level of variance. The capital market line describes combinations of the risk-free asset and market portfolio. The capital asset pricing model expresses expected returns as a linear function of systematic risk measured by beta.