Mean-variance efficient ray

Without a risk-free intercept or constraints, every undominated linear portfolio lies on the nonnegative ray through $V^{-1}b$.

Let risky excess payoff have mean $b$ and positive-definite covariance $V$. The minimum-variance portfolio with target excess expected wealth $c$ isFor constant absolute risk aversion utility with coefficient $\gamma$, the optimal Gaussian portfolio is $\theta ={\gamma }^{-1}{V}^{-1}b$. The two choices coincide when $\gamma =1/\lambda$.