Efficient frontier
Set of portfolios that give the highest return for the given level of risk
Capital market line
At a tangent to the efficient frontier- best choice
Security market line
The mean return of investment with its beta
Equation
Return=risk free rate + B(market risk- risk free rate)
Capm assumptions
All investors are efficient and want to target efficient frontier
Investors can borrow and lend any amount of money at risk rate
All investors have homogenous expectations - the same
No tax, transaction costs to buying/selling
Capital markets are correctly priced
Capm problem
Unstable betas unless are large portfolio