The Capital Asset Pricing Model (CAPM) is a simple but useful tool. Watch this weeks video for an overview.

Note that the RISK portion in the video actually incorporates both risk and time value since it uses interest rates. Thus, the CAPM is also a one-period time value tool.

In the CAPM, a securities return depends on three variables; the risk-free rate, beta, and the return on the market portfolio. Of these, which is the most difficult to estimate?

http://www.investopedia.com/terms/c/capm.asp