有效証券投資
efficient portfolio
一種完全分散的証券投資。對于給定的收益無別的投資方式可減少風險，而給定的風險水平沒有別的投資可獲取更高收益。
A completely decentralized investment securities. For a given level of income without investment risk can be reduced, and a given level of risk there is no other investment can get higher returns.