Method for predicting how investment returns are determined in an efficient capital market.
Market Portfolio
Current value of all assets.
Capital Market Line (CML)
Linear risk return trade off for all investment portfolios.
Security Market Line (SML)
Linear risk return trade off for individual stocks.
Systematic Risk
Return volatility tied to the overall market.
Unsystematic Risk
Return volatility specific to an individual company.
Diversifiable Risk
Another term for unsystematic risk.
Nondiversafiable Risk
Another term for systematic risk.
Beta
Sensitivity of a security's returns to the systematic market risk factor.
Security Characteristic Line (SCL)
Linear relation between the return on individual securities and the overall market at every point in time.
Excess Return
Security or portfolio return less the risk free rate.
Positive Abnormal Return
Above average return that cannot be explained as compensation for added risk.
Negative Abnormal Return
Below average return that cannot be explained by below market risk.
Market Index Bias
Distortion to beta estimates caused by the fact that market indexes are only imperfect proxies for the overall market.
Model Specification Bias
Distortion to beta estimates because the SCL fails to include other important systematic influences on stock market volatility.
Time Interval Bias
Beta estimation problem derived from the fact that beta estimates depend on the data interval studied.
Nonstationary Beta Problem
Difficulty tied to the fact that betas are inherently unstable.
Multifactor CAPM
Asset pricing model that assumes portfolio risk is tied to market risk and other factors, such as firm size and P/B ratio.
Arbitrage Pricing Theory (APT)
Multifactor asset pricing model that allows market betas to represent only one of the firm's many risk factors.
Arbitrage
Simultaneous buying and selling of the same asset at different prices to capture a mispricing.
Momentum
Belief that stocks with high prior returns will continue to achieve high returns in the future. Stocks with low prior returns are believed to continue earning low returns.
Noise Traders
Investors who make systematic errors when they assess the characteristics of companies and expected stock returns.
Benchmark
Diversified portfolio of similar risk or investment style used as a comparison.
Alpha
Abnormal return measured from the CAPM required rate of return.
Selectivity
Ability to pick stocks that outperform the overall stock market.
Market Timing
Investment style that attempts to buy into the stock market before a bull market move and sell before a bear market move.